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7.3 Injection Timing Thread

63K views 206 replies 43 participants last post by  old Smokey 
#1 ·
Very few of you here know who I am so I will introduce myself. My name is Matt Robinson and I am an engineer by day and someone who is currently addressing the issue of the lack of pulsewidth available on the 7.3 Powerstroke at high RPMs. I wanted to open this up to everyone to discuss. I also want to talk about injection behavior that was first brought up in the "engine failure" thread so that can be re-focused on the issue at hand.

Hopefully a good understanding of the 7.3's HEUI injection behavior will come out of this.

Matt R
 
#3 ·
Nope, background in RF and embedded computer systems but been hot rodding since a chld (not kidding). I started tuning gas cars a while back but have only been into the diesel tuning for a couple of years. There are a tiny few running my tuning out there.

I've been working on the cure for the 7.3 dropping pulsewidth starting at 2500or so rpms. I will have something ready very soon that will give the ability for the system to give full pulsewith at high rpms. Believe me... the OBDII port is lying when it says you are getting 5ms of pulsewidth at 3500 rpms.

Also we need to get some injector manufacturers in here to talk about injector speed. The timing of the actual injection event is very different on modified injectors vs stock in some cases depending on what modifications have been done. There are adders for injection advance in the tuning that are there to compensate for injector speed under various conditions. If you put a really fast injector in there who knows how much advance it is adding to the tune.......

I want to stir the pot here and see what can come out into the open without giving away any trade secrets....

Matt R
 
#4 ·
Im all for an open minded discussion on this as well. Ive worked with Matt the past year or so and weve b asically had to teach ourselves what we know from scratch and have discovered a few interesting things and have opened up a whole new realm of questions as well.

One question on my mind lately has been how do the different types of injectors (i.e hybrids, stroked a codes, shos, standard bcodes etc) vary in their response and how do the different "tricks" performed on these from the different manafacturers effect timing, fuel expelled, actual nozzle pressures etc. Hopefully some good information can be had and the powerstroke community can gain as a whole from this, as well as noones toes getting stepped on as well.
 
#5 ·
injector voltage plays a big part too (idm mod). hopefully something good will come from this thread. there are others on here studying the behavior of the idm.
 
#6 ·
yes you command the timing in the tuning... but that's the time you tell the njector to start opening.... so between a B code and a hybrid with the same nozzle size which will need less timing under most conditions for the same cylinder pressure (easy example)? I guess my point is that without cp testing on your exact combo it is hard to do tuning at the ragged edge without injectors that have been characterized and the proper adders modified in the tune.... what about the new sho mods..... how many milliseconds faster are these?
 
#7 ·
Maybe im wrong, but i think the question is being miscontrued. His point is what youre saying. The mods on the injectors can effect the actual start of timing and fuel expelled. What if the armature clearances are set tight, wotn the injector start to empty just a tad bit sooner, meaning the fuel comes into the cylinder just a little faster as well as giving it more time to the end of injection, meaning more fuel. Overall, you have more fuel sooner. the question is, how much more, and how much sooner. This information would allow the tune to be setup correctly. Obviously, cylinder pressure testing equipment as well as some other goodies Charles has talked about could give you an idea of wahts going on, but seems like a general profile for each type of injector could be determined and help a little as well.
 
#8 ·
the op wants to address the problem with pw at higher rpm's, one of the problems we have is that the idm tells the injector to open but there is a reaction time to deal with, this is where the idm mod and hpop mods help. if you could increase the injector pw with tuning or a custom idm it would be the key to making big power. there is no reason why a 360ci engine should make twice the power of a comparable 444ci engine.
 
#9 ·
Haulin, maybe im lost but im not seeing your point. At first you claimed the injector differences made no difference in timing or fuel expelled, now you claim the timing has to be jsut right. THATS THE POINT WE'RE TALKING ABOUT!. how do we know armatuer clearances arent tampered with? this is just an example by the way. im not saying they are or arent, just using as an example as a lot of things in the injectors could be messed with that would effect the end result. Say you leave the tune the same and install an injector that reacts faster. That is the only change. you now have fuel being expelled into the cylinder sooner, which effectively advanced the timing. What the OP posted is lets have a discussion about this and ponder what mods have what effects, and by how much. this could change the amount of motors blown up.
 
#10 ·
My injectors are stupid fast. I would guess that for any given pw and nozzle size that I can inject more fuel than most anyone running stock coils. Hence making damn near 430rwhp on bone stock 7 holers a couple years ago, and making 544rwhp on 7 holers with holes less than .007"

Do injectors have a variance in actual start of injection based on mechanical alterations? You had better believe it.


And Haulin. Simmer down. You're not even addressing the man's question.
 
#11 ·
to address the above statment, fuel need's to enter the cyclinder of the exact time(no sooner, no later) if it enter's to soon well it's not gonna burn,to late and you get coal out the tail pipe.no matter what cc or code injector's the armeture clearence's should not be tampered with.when you order your injector's they should already bet set to proper clearence. fuel pressure plays a vital role at this point.as well as timing.:blah:
Dude...seriously, quit making yourself look like a moron because of your stupid posts. You have brought nothing new to the table here and Matt is not talking about HPOS, timing tables, or fuel pressure...pretty sure he already knows all about that.

The question was how to make Higher PW at above 3500 RPM's You won't find that in your tuning software...Think outside the box for once.

You are posting information about don't mess with this and don't f* with that. Do you know this from experience or from reading others posts? myself along with others are reading this thread to learn about RPM's and injection timing, and the majority of us including the OP is already well aware of the different tables in the software.

I believe what Matt is talking about when he says injection Timing is how to make the injector start working earlier, therefore injecting fuel as early as the first electron hits the solenoid, that would increase injection timing. the faster you can make the injector respond to the electric pulse, the faster it will inject fuel. Also, Different VOP Springs in the injectors could adjust timing. For example if you wanted to retard timing you could install the 3700 PSI spring from a DT466E. There are also those who have been doing SHO mods (oil side mods) that allow the injectors to move the oil in and out faster, that would also increase timing because the oil is entering the injector faster, therefore forcing the intensiier piston down sooner, and therefore injecting fuel earlier.

Is that making since to anyone yet. I don't believe that this thread was totally intended for tuning software discussion. But feel free to correct me if I'm wrong Matt.
 
#12 ·
Maybe for a start lets discuss the following

Timing is directly effected by and needs to be adjusted for:

1. Engine Oil temperature-because this changes the rate at which the injector functions. Colder oil means more timing
2. RPM-because the amount of time the fuel change has to burn and to be injected. Higher RPMs means more timing
3. HP oil pressure-because this changes rate at which the injector functions. High ICP means less timing
4. Boost-because this changes the rate at which the air fuel mixture burns. More boost means ______ timing


I invite anyone that knows more then me on this subject to modify or adjust that list as needed.

The next part that perhaps we should try and discuss is the stratigy the PCM uses to adjust timing. I know there are quite a few tables that address this:

1. EOT Comp-this table adds timing and fuel when the oil is cold it might work on a multiplication priciple.
2. Base timing table
3. ?
4. ?


I would also invite those that know more to add on and correct what I have written there too.

Perhaps we can then carry on and make a similar sort of list regarding the various injector modifications and differences and work off of that.


Lastly I would at be interested to learn how much of a range of timing do these motors utilize. Is it a broad margin like 0deg to 30deg BTDC or is a more narrow margine say 10deg to 20deg BTDC?

Tom
 
#13 ·
to address the above statment, fuel need's to enter the cyclinder of the exact time(no sooner, no later) if it enter's to soon well it's not gonna burn,to late and you get coal out the tail pipe.no matter what cc or code injector's the armeture clearence's should not be tampered with.when you order your injector's they should already bet set to proper clearence. fuel pressure plays a vital role at this point.as well as timing.:blah:
Dude...seriously, quit making yourself look like a moron because of your stupid posts. You have brought nothing new to the table here and Matt is not talking about HPOS, timing tables, or fuel pressure...pretty sure he already knows all about that.

I have removed all the junk out of this thread. Lets try and make this an intellengent high value thread on a good subject. To the OP if what I posted is not what you are interested in discussing I will take that to a new thread.


Tom
 
#14 ·
praise the Lord... yes this thread is about different modified injectors and the reaction time difference from stock

the factory set the commanded timing in the tables to match the injection event via the eot, icp, and rpm modifiers once you modify an injector's operating time all bets are off.... that's what I want to discuss...

maybe I should make the pulsewidth a different thread but I am working on an idm system that doesn't start dropping pulsewidth at around 2300 or so rpms.... look at every dyno graph from a 7.3 where does the torque start to spiral downward? it is the idm cutting pulsewidth to not exceed the maximum duty cycle of the total injector firings....

Matt R
 
#16 ·
I wish someone could tell you what you're looking for, but I think for the time being its all guess work without a CP Transducer and a scope. You can flow the different injectors on a flow bench for flow rate, but in order to see when they are firing vs. Piston position, you would need them in a vehicle...I believe. Has anyone ever installed a set of SHO's with stock tuning, with a scope and CP transducer just to see how much faster the fuel starts to burn that with stock injectors or even Hybrids. How about with some mild timing table adjustments and Extreme ICP? What happens to the Peak CP when you go from stock injectors to hybrids and no special tuning? For a stock injector, every millimeter the plunger travels it injects 28.27mm^3 of fuel, but when you switch to hybrids they inject 39.59mm^3 and if you install a larger than stock nozzle then you have to account for that as well. Then take into account the VOP Spring pressure, and the Lowered injection pressure of the hybrid injector over the stock one. These are all questions that I have been wondering about also. There are also The oil side mods, which I don't believe will get much discussion here because of proprietary information that may be lost if done so.

I don't think that by making the injectors faster is the complete answer, but it sure helps.
 
#17 ·
it is the idm cutting pulsewidth to not exceed the maximum duty cycle of the total injector firings....

Interestingly the flowbench I use runs on a Ford IDM and has physically tested numerous injectors at over 2ms of pw at 6000rpm. BTW, the injectors work fine at that rpm...

4ms at 6000rpm? Not a problem either.

Are you sure it's the IDM.



Anyway, good thread.
 
#18 ·
Interestingly the flowbench I use runs on a Ford IDM and has physically tested numerous injectors at over 2ms of pw at 6000rpm. BTW, the injectors work fine at that rpm...

4ms at 6000rpm? Not a problem either.

Are you sure it's the IDM.



Anyway, good thread.
Charles, how many injectors does the flow bench test at the same time. All eight?
 
#20 ·
It tests 4. But do you think the IDM knows that?

Or better yet, what about the same kind of thing in a running truck. I can only imagine what that would be like.
It dosn't know anything other then to send the volts when it is told to. Doesn't it need to "recharge" after each event or does that happen so fast that it really is not an issue? If it does need to recharge running at 6000 rpm on your bench (4injectors) wouldn't be an issue cause it is only needing 1/2 the load?

Also, if say we start with 140volts (modded IDM) and when we get to 2500RPM are we still at 140v or are we dropping? Im sure you have tested this in the past!
 
#23 ·
Your math is absolutely correct. And I'm very happy that you saw that as the most provocative issue as opposed to anything related to voltage...

And I made no mistake in what I wrote.
 
#25 ·
so if say you want 4ms of pw at that 6000rpms do we actually have that much time to burn it effiecintly with the amount of timing we can actually run.
and also you said 4ms at 6k was that commanded or actual?
great thread guys
 
#28 ·
haha i do not know that would go back to the speed of the injector would it not? there is not suppose to be a difference i was unsure if there was enough to matter or not
 
#29 ·
I've been working on the cure for the 7.3 dropping pulsewidth starting at 2500or so rpms. I will have something ready very soon that will give the ability for the system to give full pulsewith at high rpms. Believe me... the OBDII port is lying when it says you are getting 5ms of pulsewidth at 3500 rpms.

There are plenty of tuners that have been saying otherwise for years now. They don't have any problems dropping pw because they can manipulate the PCM in ways that stave off this problem.

What do you have to say to that?
 
#30 ·
Theres a import shop right next door to twisted diesel and they specialize in turbo imports. Any ways on high hp turbo cars they remove all the oem fuel injection and install an AEM control box. This box is so sophisticated but yet very universal. They do some crazy tuning on these cars to make a 4 cyl honda lite a big ol Gt42r. The owner said that there might be a way to run it to a diesel and try to tune for more pw at higher rpms sorta like them d max's. They can control everything from the labtop. I would of thought AEM or MSD would come out with something for this problem . It would be a big hit for sure. If only there was bigger market i guess.
 
#31 ·
First of all, is it capable of full sequential injection....

If yes, is it capable of delivering the fully sequential injection pulse with a resolution of at least 1 degree crank?

For the AEM I'll go ahead and say no for you, and save you some research.


When you start thinking about full stand-alone, think about things like speedometers, cruise control, and so on. Have fun with that.


But the main thing is..... many tuners don't have this issue. So why even bother?
 
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