Ford Power Stroke Nation banner

How the PCM and IDM work

53K views 169 replies 45 participants last post by  F250Hoss 
#1 ·
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
 
#77 ·
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.
 
#78 ·
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. :bowfast: So that only leaves a couple questions :confused:

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

:confused::confused::confused::confused:
 
#80 ·
Jason, it is obvious that you are one of the few people that are actually putting serious rpm's to the ground. :bowfast: So that only leaves a couple questions :confused:

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

:confused::confused::confused::confused:
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.
 
#81 ·
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
 
#82 ·
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
 
#83 ·
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.
 
#84 ·
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
 
#85 ·
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
 
#86 ·
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
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. ;)
 
#87 ·
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
 
#88 ·
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.
 
#89 ·
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.

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
 
#90 ·
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?
 
#91 ·
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.
 
#92 ·
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.
 
#93 ·
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
 
#94 ·
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
 
#96 ·
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.

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
 
#98 ·
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.
 
#100 ·
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.
 
You have insufficient privileges to reply here.
Top