Soft Pedal

[Whippled 496]

....or at least thats what I call it. On my 2004 8.1L daily driver (not the Whipple truck) there are times when I am cruising when I can push on the gas pedal and literally push it 2 inches or more and feel almost no change in RPM or acceleration. Generally this happens when in 4th or 5th gear and cruising around 2200 - 2400 RPMs. I have tried adjusting the spark tables, VE tables, TPS table, and a few others but its made no differnce. I have almost all my Tq management pulled out so I know thats not it. This is the exact opposite of my Whippled truck as I can push on the pedal (not under boost) and feel instantaneous acceleration. I know there are a lot of mod differences bertween the two but it would seem the problem is in the tune and I cant figure where. Any tips or help would be appreciated.

Thanks,
Jimmie

[ScarabEpic22]

I know the feeling, no idea what its called either.

I believe it is spark related however, I noticed when I would add more timing to my P10 that it would feel "snappier" when playing with the gas pedal. Do you have a log when you notice this issue? Might help us track down the root cause a little easier.

Just curious if that truck has an Allison in it? Thought the 8.1s with Allisons had a separate TCM but that tune has all the trans params in it...

[Whippled 496]

yes, its a different controller (TCM) that controls the Allison. The trany perameters in the PCM do not effect tuning at all. I have tried adjusting the timing when in the soft spot using the roadrunner but it did not make a noticable diference in those dead spots.....at least it didnt seem like it did. I copied over the spark table (high and low) from the whippled truck into this one and it didnt feel a lot different. If it was spark related I would have assumed that would do it. The only differences between the two trucks (other than the MODs) is the 2003 is 4.10 gears and has a return fuel line so the injectors are not scaled. The 2004 is 3.73 gears and has a scaled injector table due to no return line. Other than that the platforms are the same. Here is a log of one of the runs.

[ScarabEpic22]

I thought so on the Allison, just thought it was weird GM would spend the time to implement the tables in the PCM.

I imagine you're running less spark on the whippled one to compensate for the boost, or are you pulling timing using a COS?

I noticed you got ~2* of knock pretty regularly in that log, might want to adjust your tune for that. Can you point out where in that log you're experiencing the soft pedal? I think around 1884 is where you do it once, and as the TPS increases watch the spark drop 7*. Have you adjusted your tip-in TM settings?

[azcagiva]

Have you tried zeroing your burst knock tables?



-John