Hp tuners; 2004.5 touchy accl pedal

Post your flow sheets... but yes I had a dumb moment 20-30% depending on how the truck runs


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There is always more than one way to do things. It sounds like you have changed quite a few things, and to at least some extent they are cancelling each other out.

IMO, to reduce a touchy pedal with large injectors, start with what HP tuners call the part throttle governor tables. This limits the initial amount of fuel that is delivered when the throttle is pressed. Next work with Boost Limit A table to keep the smoke down.

Be careful when modifying the duration (Main Injection Pulse width) table. If you notice on the stock duration table, that the minimum duration is 160us (other than 0). This is because the default value in the ecm for a minimum injection event is 160us. If you command less then that, the ecm will skip that event. This is probably the largest cause of rough idles with large injectors. It's also one of the reasons that some tuners go to single event tunes. With large injectors you will probably at the very least need to reduce pilot injection, so that the ecm can deliver at least 160us during the main event.

As far as a course of action... Go back to the stock pedal maps, and stock duration table. Adjust the two tables I mentioned, until you get the off idle, and acceleration the way you want.

Adjusting the duration table down to match the larger injectors, just means you end up with stock power with the larger injectors. If you wanted 10-20% less fuel, then you should put 10-20% smaller injectors in it.

Again... More than one way to skin a cat...

Paul
 
The reason to have a minimum pulse is due to injector latency. If you could force it to run below 100us, the injector wouldn't even inject fuel, not enough time for the pintle to lift before the solenoid shuts off again.

I agree with using a stock pulse table to start with, but you do need to reference the injector flow sheets. This will give you an idea of how much to cut in the low mm3 / mpa areas. If you don't have this info, reference what mm3 a stock truck idles at, then log what pulse your truck idles at and apply that pulse to the stock idle areas and blend it out to the rest of the table.

Remember, a 150% injector only flows that much extra at full rail pressure, so you may only need to cut 20% or so like was said before. To keep a minimum duration in the table, simply subract 160us from the table (if this is really the minimum duration required), make your desired changes, then add the 160us back in when done.
 
Last edited:
Ackerdiesel said:
Post your flow sheets... but yes I had a dumb moment 20-30% depending on how the truck runs


Sent from my iPhone using Tapatalk Pro
Click to expand...

Here's my flow sheet. My first go-round I tried to compare what these injectors flow to stock and make a tune that ran close to stock...it didnt run lol
 

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paulb said:
There is always more than one way to do things. It sounds like you have changed quite a few things, and to at least some extent they are cancelling each other out.

IMO, to reduce a touchy pedal with large injectors, start with what HP tuners call the part throttle governor tables. This limits the initial amount of fuel that is delivered when the throttle is pressed. Next work with Boost Limit A table to keep the smoke down.

Be careful when modifying the duration (Main Injection Pulse width) table. If you notice on the stock duration table, that the minimum duration is 160us (other than 0). This is because the default value in the ecm for a minimum injection event is 160us. If you command less then that, the ecm will skip that event. This is probably the largest cause of rough idles with large injectors. It's also one of the reasons that some tuners go to single event tunes. With large injectors you will probably at the very least need to reduce pilot injection, so that the ecm can deliver at least 160us during the main event.

As far as a course of action... Go back to the stock pedal maps, and stock duration table. Adjust the two tables I mentioned, until you get the off idle, and acceleration the way you want.

Adjusting the duration table down to match the larger injectors, just means you end up with stock power with the larger injectors. If you wanted 10-20% less fuel, then you should put 10-20% smaller injectors in it.

Again... More than one way to skin a cat...

Paul
Click to expand...

For the most part I've been taking the stock pw maps and taking fuel out from the low end by 10-20% at a time and adding some at the higher pressure side. When shes moving, she runs great, fantastic, outstanding...its just from the 0-10something% pedal its requesting so much fuel. I just set up the part throttle Gov and did a log...but I only did the transient map. At 10% it was still requesting 50mm3 while I had it set to 30mm3 at 30% just to see what would happen.
 
So I set up the partial throttle governor tables to be 10mm3 at 10%, 30mm3 at 30% and progressed to 120mm3 at 60%. I did a log of just rolling through the gears as daily driving. Seat of the pants it was better, didnt have that 5-10% throttle surge and didnt smoke anywhere near as bad. But when I look at the log it was still at over 50mm3 ar 10% pedal.
 

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Well, I started over from a previous tune and messed with the pedal, part throttle govenors, and boost limit tables like yall told me to. I've got it pretty good, definitely a night and day difference from what it was.
I've got a few questions: what should my boost override quantity be? In my logs, what fuel rate should I be looking at? I assume that is also including the pilot injection?
 
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