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  #1  
Old 11-04-2008, 02:53 AM
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How the PCM and IDM work

From another thread maybe you guys that have a much better understanding then I do of this can school up the masses on how the pcm and idm work and how they work together? Make me smarter then the PCM is the brain and the IDM is the electric engine to fire the injectors.

Tom
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  #2  
Old 11-04-2008, 03:04 AM
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Re: How the PCM and IDM work

School me too.
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Old 11-04-2008, 03:12 AM
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Re: How the PCM and IDM work

Okay, So the IDM is a very smart "dumb" device. It provides a high voltage wire to both banks and a ground wire to each individual injector. The PCM sends the IDM 2 important signals. CI or Cylinder Identification and FDCS (fuel delivery control signal). This tells the injectors when and how long to fire. The signals between the two only have two states High or Low (keeping it simple here). The CI signal remains high for the first four firings and goes low for the second 4 cylinder firings then this all repeats every two crankshaft rotations. The FDCS signal is merely repeated at a higher voltage and given to each injector in the right time. I will have to build an illustration unless someone beats me to it....
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Old 11-04-2008, 03:31 AM
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Re: How the PCM and IDM work

This is going to be a good thread, if it doesn't get filled with bs.
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  #5  
Old 11-04-2008, 03:32 AM
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Re: How the PCM and IDM work

I am looking at my wiring book here and on a quick inspection it looks like there are 3 wires plus a ground that connect the PCM to IDM. Does the IDM send back information to the PCM?

Tom
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Old 11-04-2008, 03:42 AM
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Re: How the PCM and IDM work

Yes. EF. Electronic feedback. It is a mirror image of FDCS returned with a slight delay.


As Matt already stated, we're talking digital communication. Hence the importance of protocol robustness for stability. Digital, meaning either on, or off. No in between.

CID goes high, then injectors 1, 2, 7, and 3 fire. CID goes low and injectors 4, 5, 6 and 8 fire. CID then goes high and again and the cycle is repeated, over and over again.

And illustration would go a mile where description would only go an inch here.

When an injector "fires" that is simply FDCS going high, the leading edge of which is literally the timing, and the width of the pulse is literally the pulsewidth where the tailing edge is the end of the injection event (electronically). These all together form an endless sequence of squarewaves, one right after another. Each one represents a single injection event.
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Old 11-04-2008, 03:44 AM
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Re: How the PCM and IDM work

Cool. Following right along.
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Old 11-04-2008, 03:50 AM
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Re: How the PCM and IDM work

see stuff makes so much more sense when someone takes the time to "dumb it down"
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Old 11-04-2008, 03:50 AM
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Re: How the PCM and IDM work

OK, so there must be a reason that the IDM needs to send the FDCS (fuel delivery control signal) back to the PCM. That would be one of the first questions I have is why it needs to do that? And taking literally what you wrote the IDM in only sending back the PCM the request that the IDM received not what the IDM actually did?
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Old 11-04-2008, 03:55 AM
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Re: How the PCM and IDM work

Charles, your explanation grew, thanks. Very clear.

Is the feedback to let the PCM know that everything is OK, don't throw an IDM code?
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Old 11-04-2008, 03:56 AM
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Re: How the PCM and IDM work

Correct.

Now go snip the EF wire. Oops, truck still runs, lol.
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Old 11-04-2008, 04:01 AM
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Re: How the PCM and IDM work

But you get a CEL, correct? ANd the code says to check for IDM codes. And of course the high is > 100 volts and the low is ground.
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Old 11-04-2008, 04:24 AM
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Re: How the PCM and IDM work

Quote:
Originally Posted by Charles View Post
Correct.

Now go snip the EF wire. Oops, truck still runs, lol.
Pretty sure I've seen that wire cut before.....

And good explanations, it's helping put together all the bits and pieces I've picked up from you Charles.

Dave
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  #14  
Old 11-04-2008, 04:27 AM
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Re: How the PCM and IDM work

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But you get a CEL, correct? ANd the code says to check for IDM codes. And of course the high is > 100 volts and the low is ground.

No, these signals are 12v. Only the output is 100+. And it's not a squarewave output.
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  #15  
Old 11-04-2008, 04:27 AM
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Re: How the PCM and IDM work

Okay here is a very crude diagram of what is going on.... who can tell me what RPM this depicts? Also since the IDM can only accept a maximum duty cycle of 80% this is how the 3.6ms was derived....

The injector output doesn't look this clean but gives the general idea of what's happening. This is the firing sequence and not the firing order depicted. I thought this might be easier to understand this way...
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Old 11-04-2008, 04:39 AM
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Re: How the PCM and IDM work

3,333.
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Old 11-04-2008, 04:42 AM
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Re: How the PCM and IDM work

Why is there a highside and a low side? Sorry if i missed this part.
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Old 11-04-2008, 04:43 AM
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Re: How the PCM and IDM work

im guessing its because in one revolution of hte motor not all 8 cyls will fire, nore in 2 revolutions?
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Old 11-04-2008, 04:55 AM
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Re: How the PCM and IDM work

High side is the "ON" state, the low side is the "Off" state, or can be inverted depending on how a circuit is designed. Low does not mean ground (although it could in some circuits).

The high and low values are circuit specific and can be anything. If you are talking about the voltages on a PCB itself typically high's and lows are in the +5vdc to -5vdc range.

The refernce to high and low is not specific to the IDM, it's used everywhere in electronics.
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  #20  
Old 11-04-2008, 05:06 AM
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Re: How the PCM and IDM work

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Originally Posted by Charles View Post
3,333.
Correct!

So from this illustration you have a total time to dedicate to an injector of 4.5ms but since the IDM can only accept a 80% duty cycle we have a maximum commanded injector PW of 3.6ms.....

Somebody do the math for 4000 rpms and show your work for complete credit (sorry guys... got harped on about this in school because i hate showing my work).....
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  #21  
Old 11-04-2008, 05:09 AM
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Re: How the PCM and IDM work

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Originally Posted by aggie View Post
im guessing its because in one revolution of hte motor not all 8 cyls will fire, nore in 2 revolutions?
4 stroke engine... so 2 revolutions fire all 8 cylinders.
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Old 11-04-2008, 06:01 AM
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Re: How the PCM and IDM work

nevermind im an idiot lol.

so the high side is the power nad the low side is the ground. the idm basically connects the dots to allow the injector to energize and open.
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Old 11-04-2008, 11:45 AM
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Re: How the PCM and IDM work

Sweet.
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Old 11-04-2008, 11:54 AM
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Re: How the PCM and IDM work

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Originally Posted by Tom S View Post
OK, so there must be a reason that the IDM needs to send the FDCS (fuel delivery control signal) back to the PCM. That would be one of the first questions I have is why it needs to do that? And taking literally what you wrote the IDM in only sending back the PCM the request that the IDM received not what the IDM actually did?
lets see if i can try its like checks and balances. the computer is always checking for a problem just as much as reading inputs and adjusting outputs. it calculates from ie. cps, icp, app, map, what the pulse width should be along with irp duty cycle etc. so it sends a signal to the idm what it wants, the idm executes that signal then relays back to the pcm saying thats done whats next, if there was a problem say the uvc harness unplugged it whould tell the pcm hey i have a problem and the pcm will default and try to adjust to keep the best runability possible due to the circmstances. most of the inputs are accurate unless there is a problem ie icp unplugged generally the engine would die but instead the pcm will set a code then default to i think 700 psi. all in an attempt to keep the engine running long enough to get help like charles said cut the ef wire the engine still runs. it doesnt have to see feedback but feels more "comfortable" when it does. since there is still icp and rpm etc the computer makes every attempt to keep the driver from being stranded. i may have made it worse but that is my understanding of how it works.
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Old 11-04-2008, 12:15 PM
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Re: How the PCM and IDM work

Clear as a bell really. I knew that logic class in the Air Force would come in handy.
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Old 11-04-2008, 12:22 PM
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Re: How the PCM and IDM work

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Originally Posted by mattr66 View Post
Somebody do the math for 4000 rpms and show your work for complete credit (sorry guys... got harped on about this in school because i hate showing my work).....
Knowns:
4000RPM
4 injection events per rev
80% duty cycle max

Unknowns:
max PW allowed?


4000RPM = 4000/60s = 66.7 (revs per second)

66.7 x 4 = 266.7 injections/sec

1/266.7 = 0.00375 secs = 3.75ms per injection event

3.75 x 0.80 = 3.0ms max PW allowed (using 80% duty cycle rule)
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Old 11-04-2008, 12:28 PM
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Re: How the PCM and IDM work

Like Patrick said, in terms of electronics, "high" and "low" simply denote one of the two possible states. You could just as easily call it on, and off. 1 and 0. Energized, de-energized, so on and so forth.

In this case it's a 12v output that sits on the line. If the PCM doesn't act it remains 12v+. The PCM then yanks them to ground. It then releases the grounds and the lines jump back to 12v. For example for FDCS it leaves the wire in the high state for the duration of the pw, then pulls it back to ground perfectly defining a "Square". Up, to the right, and back down. A series of this forms the FDCS signal.

It is a pair of modulated grounds by the PCM that forms this digital signaling.


Now I think the PCM/IDM com link is getting confused with the IDM/Injector circuits.

On the output side, there are two high side wires. One per bank. Now when someone says high side, they mean positive (using conventional current notation). It takes both a positive and a negative for electron flow, so the injector needs two wires to fire. The high side is common to all 4 injectors on each bank. It's the center wire in the UVC. This is your 120+volt wire. The next 2 wires to each side are your injector wires (in order of appearance) for that bank. The next two on each side outside that are the GP wires.

For instance. To fire injector number 1, the IDM goes high on bank one (center wire on your passenger's side UVC) and also grounds the #1 injector wire (second wire to the front from the center wire on your passenger's side UVC). The circuit is complete, and #1 fires.

The leading edge of the FDCS into the IDM determined when this would happen, and the width of that wave determined how long it would last. To fire number 3 you would do the same thing except ground the #3 injector wire instead of the number one. This would be the adjacent wire, just forward of the center wire in the passenger's side UVC.

That is the output side of the IDM. High voltage.


Might as well explain IPR while we're at it.

The IPR duty cycle (I'm rusty on this, it's been a while) is like 440hz? I think it is, so lets just pretend for now that we know that it is.

That means that 440 times per second, (that's what "Hz" means...per second) a square wave of variable duration is sent down the line. Meaning about every 2.3ms a command is given. That's the frequency. The timeframe for this pulse is also 2.3ms long. So at 100% duty cycle, the pulse would go high, and remain high for 2.3ms. As you might have guessed, that would mean that at the time it would normally go back low, it's time for the next pulse (remember it's a constant frequency) so in reality, it never actually would turn back off, and instead would simply remain high. The result would be full power output with no modulation.

In contrast a 0% duty cycle would mean that when it came time for each pulse (440 times every second) nothing would happen. Because it's 0%. It would never turn on. Meaning that the output would be 0 volts. Nothing. 440 times per second you would get nothing.

Now everything in between 0 and 100% DC is a proportion of available on time, vs off time.

For instance. Take a 50% DC. That means it's on 50% of the time and off 50% of the time. So out of our 2.3ms pulse window, it would go high at the start (every 2.3ms it does this, 440 times a second) and stay high for 1.15ms. It would then go low for the remaining 1.15ms of the possible 2.3 before the next pulse. At which point it would again go high for 1.15ms, then go low for the remaining 1.15 again. Over and over again, 440 times each second until the DC was changed.

A 25% DC would be an on time of .575ms and an off time of 1.725ms. 75% DC would be an on time of 1.725ms and an off time of .575ms, exactly the opposite of the 25% DC.

I hope that makes sense.
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Old 11-04-2008, 12:39 PM
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Re: How the PCM and IDM work

You are correct, I was confusing the com link with the IDM/Injector.

Thanks for the clarification.
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Old 11-04-2008, 12:46 PM
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Re: How the PCM and IDM work

It cut me off at the end. But here's the rest.




Oh, and I should mention. This type of signal is called Pulse Width Modulation, or PWM. With an appropriately high frequency, a device will never actually detect the fluctuations, and the resultant output might as well be an analog voltage proportionate to the average of the PWM. This is no different than as humans, watching a movie. Even though it's really still images taken one photograph at a time, when played fast enough it looks like a seemless display. Our minds cannot detect the individual frames.
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Old 11-04-2008, 12:50 PM
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Re: How the PCM and IDM work

What is the part labled CI on your diagram Matt? I understand that is the second rotation of the motor just not what CI means?

I have a question for Charles in why does it take a pair of modulated grounds instead of just a single one?

You guys are doing a good job of explaining this.

Tom
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Old 11-04-2008, 01:15 PM
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Re: How the PCM and IDM work

The CI or (cylinder identification) signal helps keep everything in sync.... ever wonder why a Powerstroke always seems to take a few revolutions to start no matter how warm it is compared to an IDI? The signals need time and revolutions to figure out when to fire the first injector for the first time.

Also the IDM isn't dumb at all, it is a computer that monitors things like current draw by the injectors and other factors. If for some reason the FDCS "freaks out" then the CI signal would allow for a faster re-sync since it can figure out where it is every time the crank rotates or every 4 injector firings.
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Old 11-04-2008, 02:17 PM
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Re: How the PCM and IDM work

Makes sense.
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Old 11-04-2008, 02:54 PM
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Re: How the PCM and IDM work

Two PWM grounds because you have two wires Tom.

CID and FDCS.
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Old 11-04-2008, 02:58 PM
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Re: How the PCM and IDM work

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Two PWM grounds because you have two wires Tom.

CID and FDCS.
And to add to what Charles says is that in digital terms the PCM "sinks" voltage to ground to drive a "0" and if you were to disconnect the FDCS and CI wires to the IDM, the IDM inputs would constantly be at a logic level of "1" since their inputs incorporate a "pull-up" resistor. That doesn't mean anything to most and isn't really important to this discussion.
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Old 11-04-2008, 04:26 PM
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Re: How the PCM and IDM work

Since the other thread was closed, lets continue this here.

Quote:
Quote:
Or better yet, I, and I'm sure many of us, would love to hear any one of you explain FDCS and CID, how they relate, and just EXACTLY what they are doing at 4200rpm with 3.5ms of pw on the line.
Since you posed the question and are sticking to your guns on what you believe is happening, let me throw a monkey wrench into this. Please understand that I'm NOT saying that this IS happening, just asking why it couldn't be (since apparently this type of functionality is used in other fuel injection systems).

WHAT IF...the PCM and the IDM use an algorithm to keep a pre-defined "minimum gap" between cylinders in the FDCS signal, an algorithm that takes RPM into account? What if the a 3ms signal at 1000rpm is really 3ms of PW (1:1 ratio), but at 4000rpm there is a 1.2:1 ratio and a 2.5ms FDCS calculates out to a 3ms injection PW? (just BS numbers I threw together for example purposes)

You asked how it would be possible for the FDCS signal to represent 3.5ms at 4500rpm without being a flatline...the above is a simple mathematical representation of how. I don't know that the algorithm would be as simple as a basic multiplier, I would think that it would take into account RPM and might be more complicated in nature...but if both the PCM and the IDM use the same one and both have a good RPM signal, no reason it couldn't happen.
Quote:
Originally Posted by Charles View Post
Sorry. You encroach on the IDM buffer and it won't play anymore. There is an algorithm that controls the PCM's own buffer that is there to maintain the signal robustness. However, it has nothing to do with the physical limitations of the IDM. If you remove this you simply jump from there to the physical choke point of the IDM. You don't need a truck to see that. Just set one on a table and keep feeding it longer and longer pw values until it chokes.'' Has nothing to do with the PCM.

And I'm not "sticking to my guns". This is just how it is. If I told you 2 + 2 = 4 then I would be "sticking to my guns" just the same.
If you test on a bench, without a truck and a PCM, how is the test valid? You don't have any load on the IDM (injectors) and you don't have the PCM side of the equation. You find the limits of the IDM when it's fed a raw PW signal without any kind of safety or algorithm the PCM might have built into the communication protocol. Your "bench" setup is not electrically the same on either the input or output side...while interesting it's not representative of what is happening in an actual truck.

If you can't make the PCM fuel passed ####rpm on the bench, you can't test passed ####rpm on the bench with a PCM...so you have to do with with a stand-along controller. Doing it without the PCM eliminates a significant part of the equation. Jody has found specific changes in the PCM that have allowed him to push the fueling passed ####rpm and accomplish what he did with Kevins truck. He is going to try to get with Kevin and scope what is ACTUALLY happening AT THE INJECTORS (where it really counts). Scoping the FDCS signal doesn't tell us anything unless we figure out for sure that there are no other algorithms in play.
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Old 11-04-2008, 04:35 PM
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Re: How the PCM and IDM work

Dennis the FDCS is the final verdict from the PCM and we know what the maximum duty cycle the IDM will accept before choking (with any controller generating FDCS). Even if you could command more than 80 percent of total available pulsewidth (100% is a straight line) from the IDM it wouldn't work because the idm starts sputtering and cutting out.
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Old 11-04-2008, 04:42 PM
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Re: How the PCM and IDM work

But what I'm suggesting is that the PCM never sends a straight line to the IDM. I'm suggesting a possible way for there to be a gap between cylinders on the FDCS signal and have it still represent more PW than the width of the actual signal.

There ARE protections in the PCM that prevent exceeding a certain RPM. Jody watched the PW on the scantool get pulled back to almost nothing...so the PCM WAS pulling the PW prior to the safety point being reached. After changing the necessary parameters (you'd be surprised as how many there are that relate to this) in the programming, the popping went away and the PW didn't dip on the scantool. How do you explain that?
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  #38  
Old 11-04-2008, 04:51 PM
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Re: How the PCM and IDM work

so that would be a "hidden" part of the protocol in the IDM that multiplies FDCS pulsewidth by some RPM factor and deliveres a bigger pulsewidth to the injectors than what FDCS dictates? That would be cool if it happened that way, and lets say it does for the sake of this post......

Say the typical injector has a .5ms lag time and you are trying to spray in the bowl at 4000 rpms with stock pistons and spray angle. How many crank degrees are you spraying fuel when you are commanding 3ms of pulsewidth? That would also mean that SOI would need to hit the bowl 24 degrees BTDC.
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  #39  
Old 11-04-2008, 05:07 PM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
I'm suggesting a possible way for there to be a gap between cylinders on the FDCS signal and have it still represent more PW than the width of the actual signal.


Am I the only one that feels dumber after reading that?


FDCS is one wire according my diagrams. I only wish we could see more than a straight line at 4200 RPMs. BBEEEEEEEEEEEEEEEEEEEEPPPPP!
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  #40  
Old 11-04-2008, 05:07 PM
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Re: How the PCM and IDM work

I'm NOT saying that there is additional data going across the wire between the PCM and IDM, I'm suggesting that since both the PCM and IDM know what the RPM is, they can both make the same adjustment in how the FDCS signal is created and interpreted at the same "trigger RPM" (if such a thing exists). Again, this is all speculation.

Lets not take this down the road of what is happening in the cylinder yet, not until we know what is actually happening at the injector electrically with Jodys new programming. He's working with Kevin to get that info. Lets solve one puzzle at a time.
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  #41  
Old 11-04-2008, 05:09 PM
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Re: How the PCM and IDM work

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Am I the only one that feels dumber after reading that?


FDCS is one wire according my diagrams. I only wish we could see more than a straight line at 4200 RPMs. BBEEEEEEEEEEEEEEEEEEEEPPPPP!
You took that one line out of context. If after a certain RPM there is a multiplier in effect, you could have an FDCS signal that is 2.5ms wide but after being run through the algorithm represents 3ms. All that is needed is for both devices to know what the RPM is and when to apply the multiplier.
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  #42  
Old 11-04-2008, 05:17 PM
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Re: How the PCM and IDM work

If Dennis' theory is plausable, what would determine pulsewidth then?

Are you saying the idm would have some preset value in it, so once it sees a "flat line" on the fdcs cable, it would just implement certain pw based purely on rpm?
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Old 11-04-2008, 05:22 PM
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Re: How the PCM and IDM work

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Originally Posted by roosterdiesel View Post
Am I the only one that feels dumber after reading that?


FDCS is one wire according my diagrams. I only wish we could see more than a straight line at 4200 RPMs. BBEEEEEEEEEEEEEEEEEEEEPPPPP!
Are you saying there is no way fuel is injected at or past 4200?
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  #44  
Old 11-04-2008, 05:28 PM
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Re: How the PCM and IDM work

a flat line would not represent no fuel, it would piss of the idm. If you go read the explanations earlier in this thread, which is why it was created, youll see how the injector firings are communicated from the pcm to the idm. the signal is carried down the fdcs wire to the idm with an cyl identifier, to tell the idm which injector to fire, and then hte pw to fire it at. The pw is told to the idm by the length of hte pulse. Now say as the rpms go up, and suppose your pw stays the same, these pulses will be getting closer to eachother as they will be coming down the line closer to eachother. At some point, the pulses will be back to back and appear as a straight line, no pulses. At this point, how is the idm to determine the pulsewidth of any injector, as it will think the pcm is just saying to turn an injector on and never back off, as there are no breaks in the pulse.
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  #45  
Old 11-04-2008, 05:34 PM
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Re: How the PCM and IDM work

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Originally Posted by aggie View Post
If Dennis' theory is plausable, what would determine pulsewidth then?

Are you saying the idm would have some preset value in it, so once it sees a "flat line" on the fdcs cable, it would just implement certain pw based purely on rpm?
I'm suggesting that there "could be" a calculation that takes place on both sides (IDM and PCM) once a certain trigger rpm is achieved. Any RPM signal into both the IDM and PCM after say 3000rpm (round number for simplicity sake) causes the FDCS signal to no longer be 1:1 (desired PW : FDCS width). Again for simplicity sake, suppose that after the mythical trigger RPM the ratio becomes 1.2:1 (PW = FDCS x 1.2). FDCS signals never "touch and become flatline", instead a 2.5ms wide FDCS signal is calculated (x 1.2) out to be 3.0ms of desired PW.

Like I said, I'm positive that it would be a more complicated formula, but this the simple math version of how it would be possible.

In theory, if the formula took into account RPM, there could be multiple steps. Maybe there is one ratio for 3000+ and another change at 3500+ and another at 4000+. Maybe it doesn't exist at all...I'm just trying to show that there IS a way that the IDM could get a request for a longer PW than the FDCS signal represents on a scope. Since both know what the RPM is, having a simple program that watches RPM and makes a change at a certain point is totally feasible.
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  #46  
Old 11-04-2008, 05:35 PM
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Re: How the PCM and IDM work

Hmm Ok I see what your saying. At what rpm would you not be able to inject any fuel. If you go down to .5ms, how many rpms would it go to before it would flat line?
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  #47  
Old 11-04-2008, 05:48 PM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
Since both know what the RPM is, having a simple program that watches RPM and makes a change at a certain point is totally feasible.


From the way I understand, the PCM is the only one that "knows" RPM. It uses the CMP signal to generate CID and FDCS that go to IDM. CID is just the signal to the IDM of which injector to fire and the FDCS dictates how long. Does the IDM take CID and derive RPM??



Holy crap....my head hurts. I've got some diagrams at home that will help some I think....they have arrows and stuff to show direction of communication. I'll try to scan them tonight if I'm not sitting on a combine.
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  #48  
Old 11-04-2008, 05:54 PM
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Re: How the PCM and IDM work

Let's not turn this thread into $hit with name calling and what not.
Dennis, I was making the point that what good does having megapulsewidth do if you are way past your mechanical window. If you are commanding 3ms of pulsewidth at 4000 rpms and getting 2.5ms of actual injection time from that you are injecting for (360*4000/60/1000=24 degrees per ms). You would be injecting for 60 degrees of crank rotation.... How much more pulsewidth than this is useful anyway?
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Old 11-04-2008, 05:59 PM
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Re: How the PCM and IDM work

How many degrees of rotation between TDC and the exhaust valve opening?




If no one cares to share the info I will document everything when I throw on the degree wheel during assembly of my engine this next week.
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Old 11-04-2008, 05:59 PM
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Re: How the PCM and IDM work

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Originally Posted by roosterdiesel View Post
From the way I understand, the PCM is the only one that "knows" RPM. It uses the CMP signal to generate CID and FDCS that go to IDM. CID is just the signal to the IDM of which injector to fire and the FDCS dictates how long. Does the IDM take CID and derive RPM??



Holy crap....my head hurts. I've got some diagrams at home that will help some I think....they have arrows and stuff to show direction of communication. I'll try to scan them tonight if I'm not sitting on a combine.
There is enough logic in Dennis's theory and the IDM to accomplish this although I will let the results of the O-scope speak for itself. You could simply put a time multiplier in the IDM's logic based on start of consecutive pulses over time thus calculating rpm iside the IDM to create this logic.
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  #51  
Old 11-04-2008, 05:59 PM
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Re: How the PCM and IDM work

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Originally Posted by roosterdiesel View Post
From the way I understand, the PCM is the only one that "knows" RPM. It uses the CMP signal to generate CID and FDCS that go to IDM. CID is just the signal to the IDM of which injector to fire and the FDCS dictates how long. Does the IDM take CID and derive RPM??



Holy crap....my head hurts. I've got some diagrams at home that will help some I think....they have arrows and stuff to show direction of communication. I'll try to scan them tonight if I'm not sitting on a combine.
RPM can be determined by either the CID or the FDCS signal. The CID has a pulse frequency of one-half of RPM (it cycles exactly once every other rev), and FDCS has a frequency of four times RPM (4 injection events per rev).

Regardless, the PCM doesn't have to be in the equation to verify this "multiplier" theory. If you use ANY controller that gives a valid FDCS and CID signal, the IDM will interpret it accordingly. It has no idea that the device controlling it is not the factory PCM. The Ecolizer guys proved that there is nothing but a 1:1 ratio across the entire RPM band.
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  #52  
Old 11-04-2008, 06:00 PM
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Re: How the PCM and IDM work

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How many degrees of rotation between TDC and the exhaust valve opening?




If no one cares to share the info I will document everything when I throw on the degree wheel during assembly of my engine this next week.
what good does this do once you are outside the bowl on the down stroke and even way before this....
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  #53  
Old 11-04-2008, 06:05 PM
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Re: How the PCM and IDM work

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what good does this do once you are outside the bowl on the down stroke and even way before this....



That's my point.......just wanted a point of reference to picture the 90ish degrees of crank angle during questioned PW.
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  #54  
Old 11-04-2008, 06:09 PM
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Re: How the PCM and IDM work

Sorry I miss read something.
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Old 11-04-2008, 06:29 PM
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Re: How the PCM and IDM work

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Originally Posted by mattr66 View Post
Let's not turn this thread into with name calling and what not.
Dennis, I was making the point that what good does having megapulsewidth do if you are way past your mechanical window. If you are commanding 3ms of pulsewidth at 4000 rpms and getting 2.5ms of actual injection time from that you are injecting for (360*4000/60/1000=24 degrees per ms). You would be injecting for 60 degrees of crank rotation.... How much more pulsewidth than this is useful anyway?
My only point is that Jody found some settings and was able to document that changing them no longer caused the PW to drop to next to nothing when trying to rev over a particular RPM. We may not be able to use 3.5ms at 4500rpm, but if we can modify the PCM to prevent the PW from dropping to almost 0 when crossing the previously set limit we can probably command a useable PW at 4000+ using the PCM and no other external electronics.
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Old 11-04-2008, 06:30 PM
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Re: How the PCM and IDM work

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Originally Posted by TXstroker01 View Post
Regardless, the PCM doesn't have to be in the equation to verify this "multiplier" theory. If you use ANY controller that gives a valid FDCS and CID signal, the IDM will interpret it accordingly. It has no idea that the device controlling it is not the factory PCM. The Ecolizer guys proved that there is nothing but a 1:1 ratio across the entire RPM band.
"Ecolizer" guys? Sorry, I must be out of that loop???
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Old 11-04-2008, 06:41 PM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
My only point is that Jody found some settings and was able to document that changing them no longer caused the PW to drop to next to nothing when trying to rev over a particular RPM. We may not be able to use 3.5ms at 4500rpm, but if we can modify the PCM to prevent the PW from dropping to almost 0 when crossing the previously set limit we can probably command a useable PW at 4000+ using the PCM and no other external electronics.

Was this accomplished by finding a secret table or setting, or by adjusting the pw to a length which would not completely piss off the idm/pcm. The pcm, as i understand it correct me if im wrong, understands the limits of the idm, so if you ask for so much more pw than it can accomplish, it will pull it way back. "begging and pleading" the pcm to give the right pw isnt a terribly new concept and it has been working well for some tuners. however, the 6.xxx ms at 4000+ rpms is not possible, even if the obd2 port is saying so. neither is the 3.7 or whatever. 4000 rpms with 80% duty cycle is capable of 3.0xx ms pw.
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Old 11-04-2008, 06:41 PM
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Re: How the PCM and IDM work

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"Ecolizer" guys? Sorry, I must be out of that loop???
There are a couple of guys around here that build a device controlled by a PC that interfaced to an IDM and simulated a PCM. You called for rpm, # of shots, and pulsewidth you pressed "go" and it ran the IDM accordingly. It would be a huellva setup to run a flowbench....
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Old 11-04-2008, 06:46 PM
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Re: How the PCM and IDM work

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Originally Posted by mattr66 View Post
There are a couple of guys around here that build a device controlled by a PC that interfaced to an IDM and simulated a PCM. You called for rpm, # of shots, and pulsewidth you pressed "go" and it ran the IDM accordingly. It is a huellva setup to run a flowbench....


Kevin:
Quote:
At what rpm would you not be able to inject any fuel. If you go down to .5ms, how many rpms would it go to before it would flat line?
Not sure if this helps, but when I sat down the one day, I could not get the injectors to fire below something like .85ms. RPM's don't matter at that point. You can still get 1.7 ms at 6k rpm...
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Old 11-04-2008, 06:47 PM
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Re: How the PCM and IDM work

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Was this accomplished by finding a secret table or setting, or by adjusting the pw to a length which would not completely piss off the idm/pcm. The pcm, as i understand it correct me if im wrong, understands the limits of the idm, so if you ask for so much more pw than it can accomplish, it will pull it way back. "begging and pleading" the pcm to give the right pw isnt a terribly new concept and it has been working well for some tuners. however, the 6.xxx ms at 4000+ rpms is not possible, even if the obd2 port is saying so. neither is the 3.7 or whatever. 4000 rpms with 80% duty cycle is capable of 3.0xx ms pw.
I'm not at liberty to specifically answer that question, Jody is a member and if he wants to be specific he can but I will not step on his toes in that arena. I will say that it's far from "begging and pleading" with the PCM.
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Old 11-04-2008, 06:48 PM
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Re: How the PCM and IDM work

And nobody is doubting that Jody has improved his tunes and can run the rpms very nicely. HotRodTractor (Jason) has been running rpms for a good while on the stock PCM.

Everyone was simply calling BS to the claimed amount of pulsewidth being run.
Our reasons are:
1. It can't happen
2. It isn't useful at that rpm anyway.
3. Someone was running a Dual IDM setup Jody tuned and it didn't work as well.... was it because the mega pulsewidth was actually command overlapping injection events, dumping way too much fuel after it could actually be used, and consuming all the HPOP oil?

There is another thread talking about high rpm power that is talking about the injection "rate" required to make high rpm power since mechanically we have less time that what the IDM is giving us to get the job done already....
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Old 11-04-2008, 06:52 PM
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Re: How the PCM and IDM work

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Originally Posted by mattr66 View Post
There are a couple of guys around here that build a device controlled by a PC that interfaced to an IDM and simulated a PCM. You called for rpm, # of shots, and pulsewidth you pressed "go" and it ran the IDM accordingly. It would be a huellva setup to run a flowbench....
Matt,

Are you one of those "couple of guy"? Is Charles? I know Charles had something running on his work bench, and I commend both of you for the work you've done. Was any of the specific "ecolizer" data published by whoever did it in the forums somewhere that I didn't see? Links?
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Old 11-04-2008, 06:56 PM
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Re: How the PCM and IDM work

Not me... I think Jim must have one as evidenced by his last post

The last of these videos will answer you question on the "popping" we are used to hearing.....



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Old 11-04-2008, 07:00 PM
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Re: How the PCM and IDM work

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Matt,

Are you one of those "couple of guy"? Is Charles? I know Charles had something running on his work bench, and I commend both of you for the work you've done. Was any of the specific "ecolizer" data published by whoever did it in the forums somewhere that I didn't see? Links?
Check out these threads (the second one is more current).

http://powerstrokenation.com/forums/...ead.php?t=6348

http://powerstrokenation.com/forums/...ad.php?t=10563

Also refer to Andy's sig (the author of these threads), as he has lots of info about the IDM on that site (or at least he did).
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Old 11-04-2008, 07:07 PM
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Re: How the PCM and IDM work

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And nobody is doubting that Jody has improved his tunes and can run the rpms very nicely. HotRodTractor (Jason) has been running rpms for a good while on the stock PCM.

Everyone was simply calling BS to the claimed amount of pulsewidth being run.
Our reasons are:
1. It can't happen
2. It isn't useful at that rpm anyway.
3. Someone was running a Dual IDM setup Jody tuned and it didn't work as well.... was it because the mega pulsewidth was actually command overlapping injection events, dumping way too much fuel after it could actually be used, and consuming all the HPOP oil?

There is another thread talking about high rpm power that is talking about the injection "rate" required to make high rpm power since mechanically we have less time that what the IDM is giving us to get the job done already....
This will be the only post I make here. For specific information Jody can post it if he so desires.

You are incorrect here. Jody did not do the tuning for the dual IDMs set up on Carson's truck. Only for the single IDM with new tuning he worked on for him based off of what info he gave Jody about his truck.

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Old 11-04-2008, 07:12 PM
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Re: How the PCM and IDM work

Andy built the controller that is running Jim's flowbench. I supplied the IDM connectors to further the understanding of the IDM/PCM setup as well as with the intentions of finding fuel at RPM.

Sorry guys there is no magic. This is how the IDM works. There are no secret tables that change these facts. There are things that can be done to make a truck run smooth at RPM, but that does not mean you are getting the PW that you see from the PCM out of the IDM.

I spin some RPMs at the pulling track. My run at Schied's was 4200+ RPMs, 4th LO. My run at London was 4000+ RPMs, 5th HI. The tuning was improved more after these runs, but the output shaft on the tranny couldn't take it. All runs were with 33" STS tires, 3.73 gears. Vidoes are on YouTube. My truck adheres to the laws of the FDCS, no matter what the OBDII port says.

Does anyone have the contact info for Carson? I need a dual IDM setup as I do have a use for it and can make it work if it is set up properly.

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  #67  
Old 11-04-2008, 07:17 PM
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Re: How the PCM and IDM work

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This will be the only post I make here. For specific information Jody can post it if he so desires.

You are incorrect here. Jody did not do the tuning for the dual IDMs set up on Carson's truck. Only for the single IDM with new tuning he worked on for him based off of what info he gave Jody about his truck.

Diane
Oh... sorry then I misread something in the other thread...

Please tell the stenographer to "strike that from the record" please.....
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Old 11-04-2008, 07:19 PM
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Re: How the PCM and IDM work

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I need a dual IDM setup as I do have a use for it and can make it work if it is set up properly.

Jason
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  #69  
Old 11-04-2008, 07:40 PM
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Re: How the PCM and IDM work

WOW, Andy (and Steve it looks like) have done some pretty in-depth work. Most of that means nothing to me, an electronics wizard I'm not.

It will be very interesting to see what the scope shows when Jody and Kevin get together.
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  #70  
Old 11-04-2008, 07:55 PM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
I'm not at liberty to specifically answer that question, Jody is a member and if he wants to be specific he can but I will not step on his toes in that arena. I will say that it's far from "begging and pleading" with the PCM.
Sorry, the question was meant as more of a hypothetical to further help understand how the pcm/idm work.
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  #71  
Old 11-04-2008, 08:04 PM
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Re: How the PCM and IDM work

Wow, I never saw those videos before.

Boy, all that hardware and software looks awefully familiar...

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  #72  
Old 11-05-2008, 12:42 AM
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Re: How the PCM and IDM work

Thanks for posting those videos and for helping me to better understand this stuff. It makes more sense then when I watched those originally by a long shot.

Tom
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  #73  
Old 11-05-2008, 01:01 AM
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Re: How the PCM and IDM work

thanks to everyone who has posted useful information in this thread, along with others... Im pretty good with the mechanical side of how every thing works, Electronics i lacked, but i'm getting some good stuff here, keep it up. Now i've got some big-boy toy stuff in my truck now i'd like to learn how to make it run better.
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  #74  
Old 11-05-2008, 01:22 AM
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Re: How the PCM and IDM work

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Originally Posted by TXstroker01 View Post
Regardless, the PCM doesn't have to be in the equation to verify this "multiplier" theory. If you use ANY controller that gives a valid FDCS and CID signal, the IDM will interpret it accordingly. It has no idea that the device controlling it is not the factory PCM. The Ecolizer guys proved that there is nothing but a 1:1 ratio across the entire RPM band.
So should it be taken as fact that from this testing that theory that Dennis presented is not a valid theory while still a darn good concept.

Tom
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  #75  
Old 11-05-2008, 01:52 AM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
WOW, Andy (and Steve it looks like) have done some pretty in-depth work. Most of that means nothing to me, an electronics wizard I'm not.

It will be very interesting to see what the scope shows when Jody and Kevin get together.

I have been way behind on the forums lately as i have been sick I just got caught up on the one that got locked and found this one a while ago. I was digging up the vids just as i got to the point where mattr66 beat me to it. It has been a while but and i havn't watched the vids (dial up) but i'm sure that one of them show how the IDM freaks out when its asked for too much.

We also have a bunch of screen shots on the page in my sig.

We are planning on starting back into the project this winter so the page should get some more updates in the next few weeks.
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  #76  
Old 11-05-2008, 02:11 AM
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Re: How the PCM and IDM work

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So should it be taken as fact that from this testing that theory that Dennis presented is not a valid theory while still a darn good concept.

Tom
Andy can comment on this more directly, but look at the scope closely for the 3900RPM/3.05ms run in the 3rd video. He states that the divisions are 500us, and the signal appears to be exactly 6 divisions (kind of fuzzy, but you can make it out if you pause the video at the right time). This tells us that the output of the IDM for this scenario is ~3.0ms, or a 1:1 ratio with the input.
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  #77  
Old 11-05-2008, 02:19 AM
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Re: How the PCM and IDM work

I think it's also important to ask yourself why the manufacturer would program anything but a 1:1 ratio for this protocol for a system that was designed to turn ~3200RPM with stock injectors/nozzles. This would most certainly add an unecessary degree of complexity to the design that would show no gains on a stock vehicle.
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  #78  
Old 11-05-2008, 02:40 AM
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Re: How the PCM and IDM work

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Originally Posted by HotRodTractor View Post

Sorry guys there is no magic. This is how the IDM works. There are no secret tables that change these facts. There are things that can be done to make a truck run smooth at RPM, but that does not mean you are getting the PW that you see from the PCM out of the IDM.

I spin some RPMs at the pulling track. My run at Schied's was 4200+ RPMs, 4th LO. My run at London was 4000+ RPMs, 5th HI. The tuning was improved more after these runs, but the output shaft on the tranny couldn't take it. All runs were with 33" STS tires, 3.73 gears. Vidoes are on YouTube. My truck adheres to the laws of the FDCS, no matter what the OBDII port says.

Does anyone have the contact info for Carson? I need a dual IDM setup as I do have a use for it and can make it work if it is set up properly.

Jason
Jason, it is obvious that you are one of the few people that are actually putting serious rpm's to the ground. So that only leaves a couple questions

How can you do this, and who is tuning your truck?

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  #79  
Old 11-05-2008, 02:59 AM
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Re: How the PCM and IDM work

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Originally Posted by sniperonhigh View Post
Jason, it is obvious that you are one of the few people that are actually putting serious rpm's to the ground. So that only leaves a couple questions

How can you do this, and who is tuning your truck?

Raises hand
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  #80  
Old 11-05-2008, 03:09 AM
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Re: How the PCM and IDM work

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Originally Posted by sniperonhigh View Post
Jason, it is obvious that you are one of the few people that are actually putting serious rpm's to the ground. So that only leaves a couple questions

How can you do this, and who is tuning your truck?

Tony Wildman is tuning my truck. Cass built my injectors. Stealth oil pump pushing the fuel. I built my motor. I am doing this using laws set forth that govern time, space, and the FDCS signal.
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  #81  
Old 11-05-2008, 03:20 AM
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Re: How the PCM and IDM work

Andy told me that there was some interest in this IDM thing again.
(This is Steve BTW)
I'll be the first to admit that those videos of the IDM controller running are terrible. I can easily acquire screen shots from the scope to my PC(which is how i got all the shots in the IDM mod page) though video is a different story.

Anyone who knows about the IDM page should also know that i had some trouble getting the IDM to function properly. The trick was in the signal edge relationships (CID,FDS). There is nothing special about how this works as i originally speculated.

I'll use this post as a synopsis(ramble) about the IDM page, what is missing and what is planned.

So, a heads up here is that the ecolizer can control a set of injectors with an IDM, a power source, and a host (that being a PC). It's pretty basic in that it accepts pulse width, rpm, and events. It sends commands out the serial port on the pc to the ecolizer. The ecolizer converts these commands into valid CID/FD signals and the IDM actuates the injectors.

While testing the ecolizer Andy found alot of limitations in the IDM itself. Initially i thought something was geeking out in my code/hardware/what have you. After looking at the signals more closely we found that everything was working correctly and it was the IDM that was cutting PW.

We double and tripple checked the power source to be sure it had enough power to run the IDM, we checked all timing of CID,FDS. Scoped injector driver outputs. There comes a point were enough is enough and that point was reached. So untill someone else can provide evidence otherwise, i will go on the premise that the IDM is the culprit.

Incase anyone is wondering about the ecolyzer: It was designed for my car, that simple. Even though i was able to hack it to run the IDM i still think the best approach here is a properly designed controller. This can be made possible by a group by in, build it yourself from a schematic, or just download the IDM page and have at it. Everything is still open as was stated at the beginning of the project. (though i've been slacking with the updates.)

The IDM's internal computer has provisions for serial load/bootstrap. And the IDM printed circuit board appears to have support for this via board level configuration jumper. What this means is that it should be possible to get the code out of the IDM's internal computer. This code would shed a great deal of light on the control mechanisms. At this point i know that the IDM has a dedicated serial wire that is brought out to a pin on the IDM header. I also suspect that the baud rate to be nonstandard considering the crystal and divide options listed in the MCU manual. And last, the voltage appears to be somewhere around 12v positive. Which doesnt quite match up to RS232C standards(though these things can be beat into submission with some hardware tweaking).

The next update of the IDM page will have a different name. I think "IDM mod" is rightfully the resistor mod. So with that said, it needs a new name and i'm open for suggestions.

Lastly, i personally do not own a truck that uses the IDM. Though i have the facilities to perform the electronic testing and development, none of this would have been possible without Andy, his truck, and all the people who have sent us spare parts(who are cited on the IDM page).

Later.
Steve
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  #82  
Old 11-05-2008, 03:22 AM
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Re: How the PCM and IDM work

Quote:
Originally Posted by TXstroker01 View Post
I think it's also important to ask yourself why the manufacturer would program anything but a 1:1 ratio for this protocol for a system that was designed to turn ~3200RPM with stock injectors/nozzles. This would most certainly add an unecessary degree of complexity to the design that would show no gains on a stock vehicle.
I was thinking this while reading this thread. Why would someone building this for stock trucks, designed to do what they do stock, not Triple or quadurple HP at 1.5 times the RPM. Most things haven't changed much in these electornics since the first ones in '94 either.

-Michael
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  #83  
Old 11-05-2008, 09:16 AM
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Re: How the PCM and IDM work

750 19.22
850 16.85
950 15
1050 13.5
1150 12.2
1250 11.2
1350 10.3
1450 9.5
1550 8.9
1650 8.3
1750 7.8
1850 7.4
1950 6.9
2050 6.5
2150 6.15
2250 5.85
2350 5.55
2450 5.25
2550 5.25
2650 5.05
2750 4.7
2850 4.45
2950 4.35
3050 4.1
3150 3.95
3250 3.84
3350 3.7
3450 3.6
3550 3.45
3650 3.35
3750 3.23
3850 3.12
3950 3.08
4050 2.9
4150 2.82
4250 2.71
4350 2.6
4450 2.55
4550 2.5
4650 2.45


Thats a copy and paste from my excel spreadsheet. On the left is the RPM and on the right is the PW at which the IDM starts to get confused just like the video shows that was posted earlier. It does have some error in it as when i made it i didnt feel like doing .01 at a time so i just did i think .05 or so.
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  #84  
Old 11-05-2008, 11:08 AM
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Re: How the PCM and IDM work

Good info Andy and I have someone also looking into getting the code out of the IDM so we can possibly manipulate it. Has anyone looked at the 30 different parameters that can be changed in the PCM to modify the FDCS signal? We have and it is interesting what it does to the fueling especially at the higher RPM.

Jody
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  #85  
Old 11-05-2008, 12:10 PM
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Re: How the PCM and IDM work

Does the PCM send an FDCS signal that resembles anything other than a square-wave PWM pulse train to the IDM (containing only timing and PW info)? How would modifying software parameters affect the electronic behavior of the PCM/IDM protocol?

Andy and Steve have shown the absolute limits of PW that the IDM will interpret as a valid signal. It doesn't matter what the PCM code is, the IDM will reject anything beyond these said limitations. Anything more would be like squeezing blood out of a turnip. Can some tuning parameters be tweaked to allow this, too? J/K
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  #86  
Old 11-05-2008, 12:32 PM
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Re: How the PCM and IDM work

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Originally Posted by DP-Tuner View Post
Good info Andy and I have someone also looking into getting the code out of the IDM so we can possibly manipulate it. Has anyone looked at the 30 different parameters that can be changed in the PCM to modify the FDCS signal? We have and it is interesting what it does to the fueling especially at the higher RPM.

Jody
Quote:
Originally Posted by TXstroker01 View Post
Does the PCM send an FDCS signal that resembles anything other than a square-wave PWM pulse train to the IDM (containing only timing and PW info)? How would modifying software parameters affect the electronic behavior of the PCM/IDM protocol?

Andy and Steve have shown the absolute limits of PW that the IDM will interpret as a valid signal. It doesn't matter what the PCM code is, the IDM will reject anything beyond these said limitations. Anything more would be like squeezing blood out of a turnip. Can some tuning parameters be tweaked to allow this, too? J/K
Please reread what Jody posted.

Why are you joking? We're not...

Just because you haven't done it, doesn't mean its impossible. There's more then one way to get blood out of a turnip.
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  #87  
Old 11-05-2008, 12:41 PM
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Re: How the PCM and IDM work

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Originally Posted by DP-Tuner View Post
Good info Andy and I have someone also looking into getting the code out of the IDM so we can possibly manipulate it. Has anyone looked at the 30 different parameters that can be changed in the PCM to modify the FDCS signal? We have and it is interesting what it does to the fueling especially at the higher RPM.

Jody
I am sure that there are things that can be done to get the most out of the FDCS signal that leaves the PCM. Paramaters that effect the way that signal is formed and shaped from the tuning tables. But one thing you can not do is go past the rules that govern that signal and the way its interpreted by the IDM.

That is the whole reason the other thread went to pot. You can not violate these rules, no matter what the PCM is telling you. Yes there are parameters that can be changed to help fuel at RPM, but you are not actually getting any more PW than the FDCS allows.

Modifying the code in the IDM to accept a greater duty cycle compounds another problem that you will find with the IDM at high RPMs..... the ability for the IDM to be able to physically maintain any kind of usefull voltage to operate the injectors.... but that is another discussion.

Jason
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  #88  
Old 11-05-2008, 12:44 PM
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Re: How the PCM and IDM work

In the face of all the evidence (and reasoning) that prove why it can't happen, forgive me if I remain skeptical when someone tells me they can "tune around" a physical limitation by manipulating some software parameters.

This discussion relates to the limitations of stock electronics (PCM and IDM). What the IDM "can possibly do with modified code" is another matter, but that's not what's being discussed.
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  #89  
Old 11-05-2008, 01:07 PM
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Re: How the PCM and IDM work

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Originally Posted by DP-Tuner View Post
Good info Andy and I have someone also looking into getting the code out of the IDM so we can possibly manipulate it. Has anyone looked at the 30 different parameters that can be changed in the PCM to modify the FDCS signal? We have and it is interesting what it does to the fueling especially at the higher RPM.

Jody
Quote:
Originally Posted by HotRodTractor View Post
I am sure that there are things that can be done to get the most out of the FDCS signal that leaves the PCM. Paramaters that effect the way that signal is formed and shaped from the tuning tables. But one thing you can not do is go past the rules that govern that signal and the way its interpreted by the IDM.

That is the whole reason the other thread went to pot. You can not violate these rules, no matter what the PCM is telling you. Yes there are parameters that can be changed to help fuel at RPM, but you are not actually getting any more PW than the FDCS allows.

Jason

Exactly Jason! (BTW- I am posting because Jody is responding to emails)

Go back and reread what Jody posted.

From Jody-"You must first find the limitations of the PCM to be able to change parameters then move on to step 2. We're on step 2. Hopefully what we find will show that the code of the IDM can be changed/munipulated to allow it to work with what I found in the PCM."


Diane
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  #90  
Old 11-05-2008, 01:39 PM
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Re: How the PCM and IDM work

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Originally Posted by SeeYa View Post
Exactly Jason! (BTW- I am posting because Jody is responding to emails)

Go back and reread what Jody posted.

From Jody-"You must first find the limitations of the PCM to be able to change parameters then move on to step 2. We're on step 2. Hopefully what we find will show that the code of the IDM can be changed/munipulated to allow it to work with what I found in the PCM."


Diane
I just wanted to note that I added information to the bottom of that post that you should go back and read. Welcome to step 2.

Also, does this mean that you now understand why we were saying that Kevin can not be actually getting the PW he was advertising at the RPM he was advertising, and that you guys now realize that the information you are recieving from the PCM is flawed?
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  #91  
Old 11-05-2008, 01:52 PM
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Re: How the PCM and IDM work

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I just wanted to note that I added information to the bottom of that post that you should go back and read. Welcome to step 2.

Also, does this mean that you now understand why we were saying that Kevin can not be actually getting the PW he was advertising at the RPM he was advertising, and that you guys now realize that the information you are recieving from the PCM is flawed?
Did you add that before or after what I posted?

What are the limitations of the FDCS signal then? If we are going to share our information please oblidge us.
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  #92  
Old 11-05-2008, 02:10 PM
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Re: How the PCM and IDM work

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Did you add that before or after what I posted?

What are the limitations of the FDCS signal then? If we are going to share our information please oblidge us.
The information posted in this thread is the limitation.... you can send a FDCS command for 3.5ms at 4200 rpms if you take the limits out of the PCM but the IDM will tell you to take a hike.

Nobody is doubting you guys have "cleaned up" the high rpm signals and that is a step in the right direction for sure.... until you get into the IDM's code however 4ms is all you will get at 3000 rpms, 3ms is all you will get at 4000 rpms and it keeps decreasing after that as rpms increase. It is the same brick wall that everyone is up against. Blasting at it with a bigger FDCS pulse won't help anthing past that point.
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  #93  
Old 11-05-2008, 02:28 PM
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Re: How the PCM and IDM work

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The information posted in this thread is the limitation.... you can send a FDCS command for 3.5ms at 4200 rpms if you take the limits out of the PCM but the IDM will tell you to take a hike.

Nobody is doubting you guys have "cleaned up" the high rpm signals and that is a step in the right direction for sure.... until you get into the IDM's code however 4ms is all you will get at 3000 rpms, 3ms is all you will get at 4000 rpms and it keeps decreasing after that as rpms increase. It is the same brick wall that everyone is up against. Blasting at it with a bigger FDCS pulse won't help anthing past that point.

This statement right here is why no one can understand what Jody has found.

Since is not the main topic of this thread. No more will be discussed about it on our end.

To make a comment in regards to the topic. You have to first know how the PCM works and how it can be munipulated and then you can find out how the IDM works and can be munipulated.

It a just like a puzzle. You can't complete the puzzle if don't have all the pieces. Each piece goes a particular way. Finding the right pieces that fit together is the key to completing the puzzle.


Diane
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  #94  
Old 11-05-2008, 02:30 PM
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Re: How the PCM and IDM work

I want to know more about the 2 IDM's thing, how did that work? How would one FDCS/CI run 2 IDM's?

That's probably super secret stuff though

-Michael
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  #95  
Old 11-05-2008, 02:48 PM
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Re: How the PCM and IDM work

Diane,
Can you post how much PW Is in the files that Jody sent us? Its the MLE1 Programs... Ben's truck usually pulls between 3800-4000RPM's down even a tight track with that programming... Thanks.
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  #96  
Old 11-05-2008, 02:49 PM
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Re: How the PCM and IDM work

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Did you add that before or after what I posted?

What are the limitations of the FDCS signal then? If we are going to share our information please oblidge us.
I edited the end of my original post to note that you will find mechanical limitations to the IDM. I am sure you can get the code out. I am sure you can modify it. I think you can increase the duty cylce to get it to accept PW closer to 90 degrees of injector solenoid on time. But you will find mechanical limitations to what the IDM can do. I am not saying anymore about what I know about this. I have lots of time, money, thought, effort, and support from others, and will not openly share beyond this. Flame me if you must.

Quote:
Originally Posted by SeeYa View Post
This statement right here is why no one can understand what Jody has found.

Since is not the main topic of this thread. No more will be discussed about it on our end.

To make a comment in regards to the topic. You have to first know how the PCM works and how it can be munipulated and then you can find out how the IDM works and can be munipulated.

It a just like a puzzle. You can't complete the puzzle if don't have all the pieces. Each piece goes a particular way. Finding the right pieces that fit together is the key to completing the puzzle.


Diane
Your right Diane. That statement right there is why no one can understand what Jody has done in tuning to correct this issues. This subject is also what got the other thread shut down. Scope a truck and compare to the information that you are recieving from the OBDII port.

Jason
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  #97  
Old 11-05-2008, 02:53 PM
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Re: How the PCM and IDM work

Thats what I want to do Jason... We have some of Jody's programming, and I want to scope it and see where its at...
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Old 11-05-2008, 02:53 PM
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Re: How the PCM and IDM work

You know, I'm sorry for the lack of thought on my part for the fuel question in the other thread. I hope this all leads to better power for all of us. It's been a while since I've seen this much effort publicly and openly going toward the cause.
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  #99  
Old 11-05-2008, 03:06 PM
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Re: How the PCM and IDM work

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Originally Posted by UNLIMITED_DIESEL View Post
Thats what I want to do Jason... We have some of Jody's programming, and I want to scope it and see where its at...
Sent you a pm..
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  #100  
Old 11-05-2008, 03:06 PM
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Re: How the PCM and IDM work

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Originally Posted by HotRodTractor View Post
I edited the end of my original post to note that you will find mechanical limitations to the IDM. I am sure you can get the code out. I am sure you can modify it. I think you can increase the duty cylce to get it to accept PW closer to 90 degrees of injector solenoid on time. But you will find mechanical limitations to what the IDM can do. I am not saying anymore about what I know about this. I have lots of time, money, thought, effort, and support from others, and will not openly share beyond this. Flame me if you must.



Your right Diane. That statement right there is why no one can understand what Jody has done in tuning to correct this issues. This subject is also what got the other thread shut down. Scope a truck and compare to the information that you are recieving from the OBDII port.

Jason
We are getting a o-scope this week. Next week we will be comparing with the FDCS fixes and without. Sorry have things planned with the kids this weekend.
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  #101  
Old 11-05-2008, 03:14 PM
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Re: How the PCM and IDM work

Thanks!
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  #102  
Old 11-05-2008, 03:24 PM
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Re: How the PCM and IDM work

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We are getting a o-scope this week. Next week we will be comparing with the FDCS fixes and without. Sorry have things planned with the kids this weekend.
There is no reason to be sorry about taking care of family plans first. I just don't like it when people insist they can defy physics. Please be sure to report your findings since you have been so adamant in defending what you believe. There are several that have been very open with how the FDCS is set up and functions and have taken great lengths to make sure everyone understands it.

Jason
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  #103  
Old 11-05-2008, 04:02 PM
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Re: How the PCM and IDM work

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Originally Posted by HotRodTractor View Post
I edited the end of my original post to note that you will find mechanical limitations to the IDM. I am sure you can get the code out. I am sure you can modify it. I think you can increase the duty cylce to get it to accept PW closer to 90 degrees of injector solenoid on time. But you will find mechanical limitations to what the IDM can do. I am not saying anymore about what I know about this. I have lots of time, money, thought, effort, and support from others, and will not openly share beyond this. Flame me if you must.



Your right Diane. That statement right there is why no one can understand what Jody has done in tuning to correct this issues. This subject is also what got the other thread shut down. Scope a truck and compare to the information that you are recieving from the OBDII port.

Jason
Jason,

We drove 24 hours round trip so Jody could live tune a few trucks before a dyno event. One of those trucks had been having issues all over the charts for months. One in particluar was a popping sound at a certain RPM. Jody did a update to the DIAGNOSTIC software he uses to monitor all kinds of parameters through the OBDII port. Prior to the upgrade to the software he could not see the PW being pulled away at that RPM. ( he had tried looking for this before and the software wouldn't allow him to see it) BAM!!! When he hooked to Kevin's truck he tried some things he had found on an auto truck in the paramters of the tuning software and that was when the popping went away. He looked at all the data and it showed what it showed. No PW was being pulled away by the PCM anymore. I don't know how much clearer it can get then that.

Believe it, or don't.

Pressing on....

Diane
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  #104  
Old 11-05-2008, 04:05 PM
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Re: How the PCM and IDM work

http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
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Old 11-05-2008, 04:08 PM
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Re: How the PCM and IDM work

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Originally Posted by UNLIMITED_DIESEL View Post
Diane,
Can you post how much PW Is in the files that Jody sent us? Its the MLE1 Programs... Ben's truck usually pulls between 3800-4000RPM's down even a tight track with that programming... Thanks.
Jody set the PW in Ben's tunes to not pull any away until 5000 rpm's. Ben's rev limiter is set for 5000 rpm's.

There's 4.5ms of PW at full throttle in Ben's tunes.
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  #106  
Old 11-05-2008, 04:13 PM
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Re: How the PCM and IDM work

THAT IS VERY INTERESTING RIGHT THERE!!! Thanks Diane. Im currently going to try to get some dyno time very soon, and verify that with our scope. Thanks again.

Was that tuning done with your latest software?
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  #107  
Old 11-05-2008, 04:16 PM
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Re: How the PCM and IDM work

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THAT IS VERY INTERESTING RIGHT THERE!!! Thanks Diane. Im currently going to try to get some dyno time very soon, and verify that with our scope. Thanks again.

Was that tuning done with your latest software?
Jody verified when he did this for Ben and yes it was.
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  #108  
Old 11-05-2008, 04:32 PM
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Re: How the PCM and IDM work

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Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
Thank you for that information.
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  #109  
Old 11-05-2008, 04:33 PM
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Re: How the PCM and IDM work

from what i understand, the OBD PORT only shows what the pcm has commanded NOT what is acually happening. like most all the outputs its whats commanded..... ie ipr is comanded to 50% thats what the pcm wants it to do based on its inputs, not nessecerialy what its doing and thats whats shown on the pids via the obd port. there is no way the pcm can tell you excatly what the outputs are doing because there is no way it can measure it. since i'm using ipr for example say it wants icp to 2000 psi the pcm commanded ipr 50% it sees the icp went up so that command was obviously excicuted weather the ipr acually went 40% or 60% the pcm doesent know it only nows that it reached its target psi. within the predetermined timeframe if not you would probbably get a p1211 so to measure outputs accuratly you must use an outside sorce ie o-scope the rest is programed in the software ie the limitations and such. (which i assum jody and diane are working on or already accomlished and are tackling the other limiting factor the idm) same concept to PW, and the various other outputs,

on a different note all you guys on here are great, very in depth and willing to help this site rules

please steer me right if i'm wrong thanks
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  #110  
Old 11-05-2008, 04:41 PM
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Re: How the PCM and IDM work

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Originally Posted by casper7.3 View Post
from what i understand, the OBD PORT only shows what the pcm has commanded NOT what is acually happening. like most all the outputs its whats commanded..... ie ipr is comanded to 50% thats what the pcm wants it to do based on its inputs, not nessecerialy what its doing and thats whats shown on the pids via the obd port. there is no way the pcm can tell you excatly what the outputs are doing because there is no way it can measure it. since i'm using ipr for example say it wants icp to 2000 psi the pcm commanded ipr 50% it sees the icp went up so that command was obviously excicuted weather the ipr acually went 40% or 60% the pcm doesent know it only nows that it reached its target psi. within the predetermined timeframe if not you would probbably get a p1211 so to measure outputs accuratly you must use an outside sorce ie o-scope the rest is programed in the software ie the limitations and such. (which i assum jody and diane are working on or already accomlished and are tackling the other limiting factor the idm) same concept to PW, and the various other outputs,

on a different note all you guys on here are great, very in depth and willing to help this site rules

please steer me right if i'm wrong thanks
Here's my post from the locked thread.


Quote:
Originally Posted by tons0torque
Dude, put a scope on it. What's the BFD? JT's not going to care.

Hey Jason!

Jody knows what was read at the OBD at the time of the popping and at what RPM it went away and didn't returrn. He also knows that there's 2 differnt PW readings in a powerstroke. Commanded and Actual. Unlike the Duramax tuning the Powerstroke only has 1 PW PID labled in the diagnostic software. Jody wants to test data with all 8 cylinders firing at 4500 rpm's while driving. Scoping it will help know the voltage signal, but it won't tell us what is actually going on in the cylinders. To him that's the most important reading to know.

Diane
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  #111  
Old 11-05-2008, 05:43 PM
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Re: How the PCM and IDM work

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Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
good info!
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  #112  
Old 11-05-2008, 06:52 PM
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Re: How the PCM and IDM work

I also want to say thanks for posting that up Jonathan.
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  #113  
Old 11-05-2008, 06:54 PM
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Re: How the PCM and IDM work

All I can say is WOW... this has been a bad A$$ thread! We have all learned now a lot about what can and can't be done when it comes to pulsewidth with the factory parts. Although some probably feel like something has been given away for free, others like myself feel like it was time that everyone gets this info so it can't be argued otherwise.

Thank you Swamps and everyone else who contributed to this thread!
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  #114  
Old 11-05-2008, 07:27 PM
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Re: How the PCM and IDM work

Thank You Swamps
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  #115  
Old 11-05-2008, 08:04 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
Jonathan,
You are simply amazing! Thanks for that incredible post!
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  #116  
Old 11-05-2008, 09:13 PM
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Re: How the PCM and IDM work

Thanks Jonathan
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  #117  
Old 11-06-2008, 01:35 AM
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Re: How the PCM and IDM work

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Originally Posted by DP-Tuner View Post
Good info Andy and I have someone also looking into getting the code out of the IDM so we can possibly manipulate it. Has anyone looked at the 30 different parameters that can be changed in the PCM to modify the FDCS signal? We have and it is interesting what it does to the fueling especially at the higher RPM.

Jody
Thanks Jody! Looking forward to see how it works out.
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  #118  
Old 11-06-2008, 02:00 AM
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Re: How the PCM and IDM work

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Thanks Jody! Looking forward to see how it works out.
This post is short and can be missed if someone is quickly skimming!

Quote:
Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
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  #119  
Old 11-06-2008, 02:25 AM
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Re: How the PCM and IDM work

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Thank You Swamps

Thanks to everyone who also contributed to turn this once confusing subject into something a bit easier to understand!
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  #120  
Old 11-06-2008, 03:31 AM
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Re: How the PCM and IDM work

Jonathan, great post. I don't know what to say. I had no idea you were that deep into it when we were fooling with my powder puff. Live and learn. You never told me either.
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  #121  
Old 11-06-2008, 03:37 AM
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Re: How the PCM and IDM work

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Jonathan, great post. I don't know what to say. I had no idea you were that deep into it when we were fooling with my powder puff. Live and learn. You never told me either.
He never told me, either!

makes that "IDM" write-up in Diesel Power (or whatever it was) a little lame, eh?

funny that guys think all we do is put a resistor in an IDM when WE mod one...
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  #122  
Old 11-06-2008, 04:12 AM
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Re: How the PCM and IDM work

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funny that guys think all we do is put a resistor in an IDM when WE mod one...
Oh boy Dave. Wonder how long it will take for the request to explain those mods?
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  #123  
Old 11-06-2008, 04:51 PM
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Re: How the PCM and IDM work

Swamp can almost literally "go in the Positive post of an IDM and come out of the ground and not get lost". Similar to someone who knows and engine good enought to "craw up the tailpipe and come out the intake" sorta thing. Rather impressive

-Michael
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  #124  
Old 11-07-2008, 12:03 AM
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Re: How the PCM and IDM work

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Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
What kind of performance gains have you been able to achieve through IDM manipulation, hardware and software? Scott
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  #125  
Old 11-07-2008, 12:30 AM
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Re: How the PCM and IDM work

honestly, not much...other than keeping stock engines together at MUCH higher hp levels than anyone else...due to increase rpm, more hp, less (destructive) tq.

as far as maxing out, retarded-type hp...we're back in this loop of electronics, injectors, nozzles, turbo's, injectors, etc.

We've been testing our "box" for nearly a year...fine tuning the electronics, addressing any chip tuning changes that have to be addressed...simultaneously attending races, and doing our day to day injectors...

Having conquered the electronic hurdle merely opened up other areas that were lacking within the HEUI system.

For every 100cc's of fuel we have to deliver in y milliseconds...we also have to flow 500-700cc's of OIL into the injector in y milliseconds...again for every 100cc's of fuel.

nice little issues arise.

Maybe I'll post a video of our injectors firing at 6000rpm with our "box" soon.

We don't have all the answers, but we at least know WHAT the questions to be answered are...

I am damn sure of one thing...and that is the limitations of the current factory electronics, regardless of WHO is tuning them.

take care~

Dave
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  #126  
Old 11-07-2008, 02:57 AM
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Re: How the PCM and IDM work

Man you guys at swamps' are great. One, for knowing the information and stuff you do, and two, for putting it out in the public for people to read, and ponder just exactly what makes common sense...
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  #127  
Old 11-07-2008, 03:03 AM
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Re: How the PCM and IDM work

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Man you guys at swamps' are great. One, for knowing the information and stuff you do, and two, for putting it out in the public for people to read, and ponder just exactly what makes common sense...


Dave
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  #128  
Old 11-07-2008, 03:17 AM
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Re: How the PCM and IDM work

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Man you guys at swamps' are great. One, for knowing the information and stuff you do, and two, for putting it out in the public for people to read, and ponder just exactly what makes common sense...
I appreciate the comment.
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  #129  
Old 11-07-2008, 03:19 AM
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Re: How the PCM and IDM work

Kudos to you guys Dave.
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  #130  
Old 11-07-2008, 03:20 AM
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Re: How the PCM and IDM work

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I appreciate the comment.
And it's not just in this thread either. Dave himself has went out of his way even after hours (just like now) helping me with things in the past, that he didnt need to do, he had no benefit form doing so other than helpin' some random guy out.. Guess thats how you do business down there.
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  #131  
Old 11-07-2008, 03:48 AM
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Re: How the PCM and IDM work

I feel like a homo if I respond to this...but thanks















(awaits someone to quote the first 5 words, and add to their sig)
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  #132  
Old 11-07-2008, 03:54 AM
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Old 11-07-2008, 04:51 AM
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Re: How the PCM and IDM work

Kris, you ought to call or PM me. Or don't. Your call.
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  #134  
Old 11-07-2008, 12:25 PM
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Re: How the PCM and IDM work

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I feel like a homo if I respond to this...

I think these threads have went from heated to way too touchy feely for me.....




















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  #135  
Old 11-07-2008, 12:30 PM
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Re: How the PCM and IDM work

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  #136  
Old 11-07-2008, 03:27 PM
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Re: How the PCM and IDM work

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Maybe I'll post a video of our injectors firing at 6000rpm with our "box" soon.

take care~

Dave
That sound like a great little clip to see.
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  #137  
Old 11-08-2008, 09:57 PM
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Re: How the PCM and IDM work

Never have I thoroughly enjoyed an educational thread so much. Fun taxing the brain so hard. Funner actually finding out that my brain still has retained some of this electronics it learned back in the late seventies, thus allowing me to follow this thread and actually learning how our trucks work. It blew my bosses mind when he asked me about the HEUI system and I was able to give him a quick basic rundown of it.
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  #138  
Old 11-11-2008, 05:36 AM
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Re: How the PCM and IDM work

Subscribing...
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  #139  
Old 11-11-2008, 08:27 AM
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Re: How the PCM and IDM work

Quote:
Originally Posted by PowerstrokeJunkie View Post
Man you guys at swamps' are great. One, for knowing the information and stuff you do, and two, for putting it out in the public for people to read, and ponder just exactly what makes common sense...
Would this excellent info in this thread qualify as a sticky?
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  #140  
Old 11-11-2008, 01:16 PM
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Re: How the PCM and IDM work

Hey Dave, I fixed my signature for you....
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  #141  
Old 11-11-2008, 02:00 PM
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Re: How the PCM and IDM work

thanks...
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  #142  
Old 11-11-2008, 10:44 PM
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Re: How the PCM and IDM work

I am having pcm problems and one guy said it could be the grounding tab on the pcm. I didnt see one. He said it was on the bottom bolt on the pcm bracket in the cab. Is this really true? I cant see were a pcm grounding tab would connect to the pcm anyway. The only connections is to the pins that connected to the connector thought the firewall.
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  #143  
Old 11-12-2008, 01:34 AM
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Re: How the PCM and IDM work

The grounding tab is a small spring that is connected to the mounting bolt area. A lot of people drop it out when installing a chip never to be found again. Look at the holder and you can see a slot from the lower bolt hole into the holder that the spring would fit and rub on the case of the PCM.

As far as the limits of what you can do in the cylinder those will never change so once those are reached all the electronics in the world is not going to fix anything. The truth is that it's going to take getting all the fuel into the cylinder in ~ 2 ms to make high power at higher RPM's. That is where the HEUI system gets itself into trouble. If you can get the injector to deliver ~250 mm3 fuel in ~2 ms and get it to repeat that at 4000 RPM the 7.3L will come around in the power department. That is about the current limit for a big single charger fuel only motor. Twins can use more fuel as can a NOS motor. At 5000 RPM you got to do it quicker! In my mind that is step #1 to getting the problem resolved. Now if you want to run the power up to where current Cummins and Duramaxs are at the fuel rate will need to be higher ~ 300 mm3 @ 2ms.

With enough money it might happen but so far I've not seen or heard of a HEUI injector system getting that done.
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  #144  
Old 11-12-2008, 01:19 PM
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Re: How the PCM and IDM work

Golfer,
This just came to mind and I was wondering if you guys have any thoguths on this.
A salesman trying to set me up to sell reman IDM's told me that as the trucks age they tend to loose their ground connections. And when and IDM 'goes out' and you replace it with a reman and it doesn't work, it's the grounds causing that. He said the IDM's adjust, or learn to deal with the poor, diminishing grounds over time. And the new IDM wants good fresh grounds.
I have no electronics knowledge so I don't know whether to believe him or not.
From your research, is this even possible with the IDM?
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  #145  
Old 11-12-2008, 01:42 PM
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Grounds

Jim, there is no "learning"; one could say that there is compensation of sorts, but not in a corrective way.
With the road salt used up noth, you will see way more grounding problems than we ever will.
The IDM case grounds via the bracket / bolts and R&R'ing them will restore contact. I have measurud as much as 75 volts on ungrounded cases !
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  #146  
Old 11-12-2008, 06:08 PM
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Re: How the PCM and IDM work

Thanks for the reply, Jonathan.
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  #147  
Old 11-12-2008, 06:17 PM
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Re: How the PCM and IDM work

Does it really matter about chassis ground to the case? There is a common electircal ground between the PCM and IDM that is isolated from the chassis and the IDM provides both positive and negative to the Injectors. Just curious to see what problems are caused from the case of the IDM floating....
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  #148  
Old 11-12-2008, 06:40 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by Swamp View Post
http://www.swampsdiesel.com/PCM-IDM.htm

This is what I've been doing for the last 3 years.
Link is dead or am I missing something?
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  #149  
Old 11-12-2008, 08:36 PM
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Re: How the PCM and IDM work

I guess they took it down.
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  #150  
Old 11-12-2008, 09:06 PM
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Re: How the PCM and IDM work

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Originally Posted by ITPDiesel View Post
I guess they took it down.
I guess not.

http://www.swampsdiesel.com/IDM/Project%20Overview.htm
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  #151  
Old 11-12-2008, 09:16 PM
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Re: How the PCM and IDM work

My head is reeling lol...

But still, could it be possible to either re-engineer the electronics in the injector to act faster/stronger with a given voltage or heck, even re-engineer the entire IDM to new standards to allow to do its thing faster?

When will the factory IDM's internal transformers start to become a limitation in terms of getting enough transformed current through to the injectors? I assume thats how it does it.. I know of no other way to increase voltage by 8-10 times...

Or am I totally missing something.

Sweet thread
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  #152  
Old 11-12-2008, 09:22 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by CtG View Post
When will the factory IDM's internal transformers start to become a limitation in terms of getting enough transformed current through to the injectors? I assume thats how it does it.. I know of no other way to increase voltage by 8-10 times...

Or am I totally missing something.
It is minature hamsters and Pixie dust.... that's why it quits working when it gets wet because the hamsters drown.

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  #153  
Old 11-12-2008, 10:08 PM
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Re: How the PCM and IDM work

Well no matter how fast you make the electronics (electricity is pretty fast already, lol), you still will not overcome fluid dynamics, it can only move so fast and in certain instances forcing it to go faster at a higher pressure will actually work against you, so i've heard. Sure you can enlarge passages and such, but there is a limit. As the RPM's get higher, it's just harder to move both fuel and oil into and out of the injector in the 48* of crank rotation needed (electronically less)

Or, just make some slugs out of steel that fits in the head and a duramax injector goes inside that, then never worry about high pressure oil or rev limitations again.
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  #154  
Old 11-13-2008, 11:04 PM
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Re: How the PCM and IDM work

WOW i learned so much from this thread...
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  #155  
Old 11-23-2008, 06:11 AM
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Post Re: How the PCM and IDM work

I've breezed through this thread more than a few times and I have actually learned a great deal from many of the posts. It's quite interesting to see everyone's take on what is going on with the relationship between the IDM and the PCM in regards to FDCS. Now if I may, I would offer this…

Pretty much every post regarding numbers has put this theoretical maximum at 3.00ms at 4000 RPM. This was validated mathematically by TXstroker in the following calculations:

4000RPM = 4000/60s = 66.7 (revs per second)
66.7 x 4 = 266.7 injections/sec
1/266.7 = 0.00375 secs = 3.75ms per injection event
3.75 x 0.80 = 3.0ms max PW allowed (using 80% duty cycle rule)

Using the same formula, let's review something similar to what Mustang_GT_350 posted:

RPM PW ms @ 80% DC
3000 4.000
3250 3.692
3500 3.429
3750 3.200
4000 3.000
4250 2.824
4500 2.667
4750 2.526
5000 2.400
5250 2.286
5500 2.182
5750 2.087
6000 2.000

If anyone doesn’t agree with these numbers, please let me know. For now, I'm going on the assumption that these are an accurate representation of what the IDM can handle without "flatline". Oh, and my numbers are a *little* different than Mustang's, but he was using a value other than 80% pwm... somewhere closer to 78% I believe.

What everyone seems to keep overlooking is that fact that as long as you don't request more ms on time than the IDM can handle, it would trigger fine up to 6000 RPM. Of course, whether the injectors are capable of handling it is another story. In fact, the PW is above 1 ms @ 80% DC all the way to 12,000 RPM! Of course the pistons would be welded to the cylinders by then.

So what's the point if we can't go above say, 3 ms @ 4000 RPM? The point is you don't have to go above 3.0ms. In fact, you don't have to go above 2.5 ms which will still get you to 4750 RPM quite nicely. Why? Again, everyone seems to overlook the obvious.

It takes 2 things to fire the injector: Time and OIL PRESSURE! There is no "magic parameter" to achieving 4500 RPM. It simple… Just don't ask for more PW than the IDM can handle and then crank the hell out of the ICP to get the injected fuel mass to an acceptable level. of course, bigger injectors do help!

I've tuned trucks that run well over 4500 RPM with zero problems. All you need to have is enough oil pressure to fire the injectors and deliver the necessary mass of fuel to make the engine run at that RPM. Consider the following maps:

Click images for the BIGGER pictures...

Stock...


Modified (What NOT to do)...


Added this just because it's in there...


If you look closely at the Injection Pulsewidth table, you'll see that by 70 mg/stroke of fuel mass that you are well over 3.00ms. Now take a close look at the Mass Fuel Desired tables and you'll notice something funny... the mass fuel desired DROPS as the RPMs increase. Hmmm, I wonder why? Maybe because as you get over 3000 RPM bad things start happening by commanding too much pulsewidth. That, and the fact that these engines were never intended to run over 2750 RPM in the first place. If that was the case, they would have put bigger injectors and bigger HPOPs and ran the HP Oil to 3800 psi like they do in the 530's. For what it's worth, the second pwm table was found in a vehicle that would cut out, pop, sputter, and fart like mad over about 3700 RPM. With some TLC and a little massage of just this table... 4200 RPM no sweat.

I'll be the first to admit that there are some benefits to tweaking the IDMs and I commend John and Dave and the guys at Ecolyzer (sp?) for the fine work they've done on explaining the IDM. However, without a thorough understanding of what exactly is going on inside the PCM, everyone is really only looking at half the picture. As I said, 4500... even 5000 RPM is attainable with the right combination of hard parts and tuning, but you may have to give a little here to get a little there.

I hope this helps shed a little more light on the subject.
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  #156  
Old 11-23-2008, 12:17 PM
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Re: How the PCM and IDM work

I support your theory, I've always thought you could "adjust" injector latency by adding more ICP, but I think you will find that the guys with a flow bench can disprove this; something about poppets floating at high pressures. That's not to say that this can't be overcome eventually, but I don't think it's a viable solution yet.

Also the HEUI 466 and 530's run the same rail pressure or close to what 444's run. The nozzle spring rate is 3650psi.

There's also something to be said about being able to "scale" the fuel correctly throughout a given RPM range. Wouldn't it be nice to have 4ms of adjustable PW to 5000rpm without the need to cross fingers, light candles and chant to the IDM gods?
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  #157  
Old 11-23-2008, 04:32 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by tons0torque View Post
There's also something to be said about being able to "scale" the fuel correctly throughout a given RPM range. Wouldn't it be nice to have 4ms of adjustable PW to 5000rpm without the need to cross fingers, light candles and chant to the IDM gods?
The linear fueling thing.... I'm doing that now. But my question to you is what good is 4ms of PW at 5000 rpms? Think overlapping injection events and time to hit the piston bowl.....
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  #158  
Old 11-23-2008, 07:22 PM
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Re: How the PCM and IDM work

I know you can't overlap CID channels. I'm just saying ultimately it would be "nice" to have a scalable fuel range to 5000rpm's.
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  #159  
Old 11-23-2008, 07:47 PM
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Re: How the PCM and IDM work

But a 4000 rpms you only have around 2ms to to get the fuel in there to do any good on "most" combos.... let's not forget about the "mechanical" limitations of most combinations. I was just making that point.
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  #160  
Old 11-23-2008, 08:10 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by tons0torque View Post
Also the HEUI 466 and 530's run the same rail pressure or close to what 444's run. The nozzle spring rate is 3650psi.
Year ago, Dipaco (I think) had a breakdown chart of all the injectors including bore size, nozzle configurations, flow rates, spring pressure, and peak operating ICP. I thought I had a copy of that somewhere but I can't seem to find it. In any event, I distinctly remember there being a specific injector configuration that utilized 3800 psi injection pressures. If I'm wrong, I'm wrong but that's how I remember it. They say when you hit 40 the mind is the first thing to go.
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  #161  
Old 11-23-2008, 08:44 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by PowerHungry View Post
Year ago, Dipaco (I think) had a breakdown chart of all the injectors including bore size, nozzle configurations, flow rates, spring pressure, and peak operating ICP. I thought I had a copy of that somewhere but I can't seem to find it. In any event, I distinctly remember there being a specific injector configuration that utilized 3800 psi injection pressures. If I'm wrong, I'm wrong but that's how I remember it. They say when you hit 40 the mind is the first thing to go.

Bill that was not oil pressure, or ICP...on that chart it is listed as VOP...valve opening pressure...as in , NOZZLE "pop" pressure...nothing at all to do with ICP. Basically a stiffer nozzle spring. THhe large HEUI injectors (BD's for example) have a nozzle that flows twice what a 7.3 nozzle flows...to keep some semblance of injector control, the mfr added a much stiffer nozzle spring to prevent over fueling at lower pulse width.

...and you're not the only one to corn-fuse that VOP value...as being an "ICP" ... or oil pressure.

take care~

Dave
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  #162  
Old 11-23-2008, 08:48 PM
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Re: How the PCM and IDM work

Bill,

According to Dipaco the nozzle spring pressure on the 466/530 motors opens at 3700psi while the A code or powerstroke injector springs are like 2650psi. Coudl this be what you were remembering?

On edit:
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  #163  
Old 11-23-2008, 09:18 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by aggie View Post
Bill,

According to Dipaco the nozzle spring pressure on the 466/530 motors opens at 3700psi while the A code or powerstroke injector springs are like 2650psi. Coudl this be what you were remembering?

On edit:
Quite possibly. Like I said, it was a LONG time ago and I wasn't sure if I even remembered it correctly. It just seemed to me that it was 3800.

Dave, thanks for correcting me on that. I always defer to the knowledge and opinions of those who understand better than I. I'll make sure not to make the same mistake twice.
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  #164  
Old 11-29-2008, 09:06 PM
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Re: How the PCM and IDM work

All you guys working on tuning. Here is something i recently ripped from the IDM ROM.

Sorry about the table alignment (i'll fix that when i fugure out what it is)

If you look closely at the table you will notice that every other entry is limited in range to 7. That is 0-7 which may or may not represent 8 injectors.

I have no clue what this table is yet.


EE87 .byte 0x00,0x01,0x00,0xC8,0x03,0xE8,0x00

EE8E .byte 0x02,0x00,0xC8,0x04,0xB0,0x00,0x04,0x01
EE96 .byte 0x90,0x00,0xC8,0x00,0x08,0x01,0x90,0x01
EE9E .byte 0x90,0x00,0x10,0x01,0x90,0x05,0x78,0x00
EEA6 .byte 0x20,0x01,0x90,0x02,0x58,0x00,0x40,0x01
EEAE .byte 0x90,0x03,0x20,0x00,0x80,0x01,0x90,0x03
EEB6 .byte 0xE8,0x01,0x01,0x01,0x90,0x04,0xB0,0x01
EEBE .byte 0x02,0x01,0x90,0x06,0x40,0x01,0x04,0x02
EEC6 .byte 0x58,0x00,0xC8,0x01,0x08,0x02,0x58,0x01
EECE .byte 0x90,0x01,0x10,0x02,0x58,0x05,0x78,0x01
EED6 .byte 0x20,0x02,0x58,0x02,0x58,0x01,0x40,0x02
EEDE .byte 0x58,0x03,0x20,0x01,0x80,0x02,0x58,0x03
EEE6 .byte 0xE8,0x02,0x01,0x02,0x58,0x04,0xB0,0x02
EEEE .byte 0x02,0x02,0x58,0x06,0x40,0x02,0x04,0x04
EEF6 .byte 0xB0,0x00,0xC8,0x02,0x08,0x04,0xB0,0x01
EEFE .byte 0x90,0x02,0x10,0x04,0xB0,0x05,0x78,0x02
EF06 .byte 0x20,0x04,0xB0,0x02,0x58,0x02,0x40,0x04
EF0E .byte 0xB0,0x03,0x20,0x02,0x80,0x04,0xB0,0x03
EF16 .byte 0xE8,0x03,0x01,0x04,0xB0,0x04,0xB0,0x03
EF1E .byte 0x02,0x04,0xB0,0x06,0x40,0x03,0x04,0x05
EF26 .byte 0x78,0x00,0xC8,0x03,0x08,0x05,0x78,0x01
EF2E .byte 0x90,0x03,0x10,0x05,0x78,0x05,0x78,0x03
EF36 .byte 0x20,0x05,0x78,0x02,0x58,0x03,0x40,0x05
EF3E .byte 0x78,0x03,0x20,0x03,0x80,0x05,0x78,0x03
EF46 .byte 0xE8,0x04,0x01,0x05,0x78,0x04,0xB0,0x04
EF4E .byte 0x02,0x05,0x78,0x06,0x40,0x04,0x04,0x06
EF56 .byte 0x40,0x06,0x40,0x04,0x08,0x07,0x08,0x00
EF5E .byte 0xC8,0x04,0x10,0x07,0x08,0x01,0x90,0x04
EF66 .byte 0x20,0x07,0x08,0x02,0x58,0x04,0x40,0x07
EF6E .byte 0x08,0x03,0x20,0x04,0x80,0x07,0x08,0x03
EF76 .byte 0xE8,0x05,0x01,0x07,0x08,0x04,0xB0,0x05
EF7E .byte 0x02,0x07,0x08,0x05,0x78,0x05,0x04,0x06
EF86 .byte 0x40,0x00,0xC8,0x05,0x08,0x06,0x40,0x01
EF8E .byte 0x90,0x05,0x10,0x06,0x40,0x02,0x58,0x05
EF96 .byte 0x20,0x06,0x40,0x03,0x20,0x05,0x40,0x06
EF9E .byte 0x40,0x03,0xE8,0x05,0x80,0x06,0x40,0x04

Now , if that is not enough there is another table.

Notice that the second entry in this table is 0x49, and the entry directly below is 0x4a, then 0x4b and so on. This table is ascending in terms of indexing.
The table is formatted by 8 bytes. It may be offset in either direction as i have no clue what it is yet.


EFDF .byte 0x00,0x49,0x7F,0x28,0x28,0x04,0xEE,0x87
EFE7 .byte 0x00,0x4A,0x7F,0x28,0x28,0x04,0xEE,0x8D
EFEF .byte 0x00,0x4B,0x7F,0x1E,0x0A,0x04,0xEF,0x23
EFF7 .byte 0x00,0x4C,0x7F,0x1E,0x0A,0x04,0xEF,0x29
EFFF .byte 0x00,0x4D,0x7F,0x1E,0x0A,0x04,0xEF,0x2F
F007 .byte 0x00,0x4E,0x7F,0x1E,0x0A,0x04,0xEF,0x35
F00F .byte 0x00,0x4F,0x7F,0x1E,0x0A,0x04,0xEF,0x3B
F017 .byte 0x00,0x50,0x7F,0x1E,0x0A,0x04,0xEF,0x41
F01F .byte 0x00,0x51,0x7F,0x1E,0x0A,0x04,0xEF,0x47
F027 .byte 0x00,0x52,0x7F,0x1E,0x0A,0x04,0xEF,0x4D
F02F .byte 0x00,0x53,0x7F,0x1E,0x0A,0x44,0xEE,0xF3
F037 .byte 0x00,0x54,0x7F,0x1E,0x0A,0x84,0xEE,0xF9
F03F .byte 0x00,0x55,0x7F,0x1E,0x0A,0x44,0xEE,0xFF
F047 .byte 0x00,0x56,0x7F,0x1E,0x0A,0x44,0xEF,0x05
F04F .byte 0x00,0x57,0x7F,0x1E,0x0A,0x84,0xEF,0x0B
F057 .byte 0x00,0x58,0x7F,0x1E,0x0A,0x44,0xEF,0x11
F05F .byte 0x00,0x59,0x7F,0x1E,0x0A,0x84,0xEF,0x17
F067 .byte 0x00,0x5A,0x7F,0x1E,0x0A,0x84,0xEF,0x1D
F06F .byte 0x00,0x5B,0x7F,0x28,0x03,0x01,0xEE,0x93
F077 .byte 0x00,0x5C,0x7F,0x28,0x03,0x02,0xEE,0x99
F07F .byte 0x00,0x5D,0x7F,0x28,0x03,0x01,0xEE,0x9F
F087 .byte 0x00,0x5E,0x7F,0x28,0x03,0x01,0xEE,0xA5
F08F .byte 0x00,0x5F,0x7F,0x28,0x03,0x02,0xEE,0xAB
F097 .byte 0x00,0x60,0x7F,0x28,0x03,0x01,0xEE,0xB1
F09F .byte 0x00,0x61,0x7F,0x28,0x03,0x02,0xEE,0xB7
F0A7 .byte 0x00,0x62,0x7F,0x28,0x03,0x02,0xEE,0xBD
F0AF .byte 0x00,0x63,0x7F,0x1E,0x0A,0x41,0xEE,0xC3
F0B7 .byte 0x00,0x64,0x7F,0x1E,0x0A,0x82,0xEE,0xC9
F0BF .byte 0x00,0x65,0x7F,0x1E,0x0A,0x41,0xEE,0xCF
F0C7 .byte 0x00,0x66,0x7F,0x1E,0x0A,0x41,0xEE,0xD5
F0CF .byte 0x00,0x67,0x7F,0x1E,0x0A,0x82,0xEE,0xDB
F0D7 .byte 0x00,0x68,0x7F,0x1E,0x0A,0x41,0xEE,0xE1
F0DF .byte 0x00,0x69,0x7F,0x1E,0x0A,0x82,0xEE,0xE7
F0E7 .byte 0x00,0x6A,0x7F,0x1E,0x0A,0x82,0xEE,0xED
F0EF .byte 0x00,0x6B,0x7F,0x1E,0x0A,0x04,0xEF,0x59
F0F7 .byte 0x00,0x6C,0x7F,0x1E,0x0A,0x04,0xEF,0x5F
F0FF .byte 0x00,0x6D,0x7F,0x1E,0x0A,0x04,0xEF,0x65
F107 .byte 0x00,0x6E,0x7F,0x1E,0x0A,0x04,0xEF,0x6B
F10F .byte 0x00,0x6F,0x7F,0x1E,0x0A,0x41,0xEF,0x71
F117 .byte 0x00,0x70,0x7F,0x1E,0x0A,0x82,0xEF,0x77
F11F .byte 0x00,0x71,0x7F,0x1E,0x0A,0x04,0xEF,0x7D
F127 .byte 0x00,0x72,0x7F,0x1E,0x0A,0x00,0xEF,0x53
F12F .byte 0x00,0x73,0x7F,0x01,0x02,0x04,0xEF,0x53

There are some other tables. One of which i figured out. It maps the injector numbers and left right feeder channels. Another seems to be an ADC correction table (used for the high voltage monitoring code)

I see no reason to think that these are anything other than tables. I've searched the ROM for functions or structures in case these were pointers. I did not find anything that would suggest otherwise.
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  #165  
Old 11-30-2008, 12:17 AM
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Re: How the PCM and IDM work

I had to chime in so I can keep a track of all this.sorry if I make anyone mad just really wanted to watch where this goes. THANKS
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  #166  
Old 12-15-2008, 01:51 PM
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Re: How the PCM and IDM work

subscribing
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Old 03-03-2009, 10:58 PM
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Re: How the PCM and IDM work

high and low whats to differcnce dose that mean 4 cyl. are making more power than the other 4 and is that why i keep getting cyl8 missfire code
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  #168  
Old 03-09-2009, 05:50 PM
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Re: How the PCM and IDM work

With all of that been said what is your opinions of the reprogrammed IDM modules from BDP? its supposed to increase the injectors by around 30hp woudl this be good or bad?
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  #169  
Old 03-09-2009, 06:44 PM
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Re: How the PCM and IDM work

Quote:
Originally Posted by F250Hoss View Post
With all of that been said what is your opinions of the reprogrammed IDM modules from BDP? its supposed to increase the injectors by around 30hp woudl this be good or bad?
I'm pretty sure that BDP doesn't offer reprogrammed IDM modules. They do however offer Modded IDMs that increase the output voltage to 140V. That is a worthwhile modification to have done.
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Old 03-09-2009, 08:36 PM
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Re: How the PCM and IDM work

Yeah you are correct that is my fault.. Does it add any extra wear and tear on the injectors or anything thing else?
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