Light Throttle Hestitation/Surging

[DIESELMAX403]

I know this has been talked about before, but I could not find a post that gave a definite fix. When manuevering my vehicle around a parking lot or driveway or accelerating from a stop and then backing right off to make a sharp turn, I sometimes get a hestitaion and then a surge. When this occurs, it is always at light throttle position. Have any of you that have experienced this problem found a fix? I remember reading somewhere that this was a symptom of a bad accelerator pedal, but I cannot find the post. I have had it into the dealer twice but they said there was no problem.

Focusing on the pedal, I played around with different throttle positions with the engine running and the vehicle in park. If I press down the throttle a small amount, the RPMs go up and then right back down to idle, however, the throttle is still pressed down slightly. When I release the pedal, the RPMs remain the same. If I press the pedal further, the RPMs pick back up. This can explain the hesitations/surging I sometimes get with light throttle movements. It seems like there is a spot in the pedal that is losing contact. Unless I hear of another fix, my next plan is to buy a new pedal position sensor when I figure out the right part number.

Any replies would be appreciated.

Thanks,
DieselMax403

[DmaxMaverick]

I don't think it is the APP. It has a built in triple redundancy. There are 3 voltage ranges required for it to work properly. If one fails, you get the SES and a code for the pedal. If 2 fail, it will go into limp mode. All 3 ranges have to be linear with each other, or the PCM will assume it is failing. GM has acknowledged the issue as normal. All "drive by wire" systems have some quirks. The LLY seems to experience this less, and the LBZ doesn't seem to have it at all. It has to be a software or EDU issue (LBZ doesn't have an EDU), as all of them use the same pedal technology. Mine does it, and I don't like it, but it isn't something I can't live with.

[DIESELMAX403]

DmaxMaverick,

Thanks for the info. You saved me the cost of a new APP sensor. I quess I'll have to live with it untill my next Duramax.

Regards,

DieselMax403

[Kennedy]

A worn/sticky/lazy pressure regulator on the pump or a restricted fuel filter could also cause this. Fuel additives play a vital role in these modern engines...

[SoTxPollock]

I used to think mine was doing what you described until I tried planting my foot firmly to the carpet on the side of the petal before touching it. I found out it is so sensitive that any small bump in the parking lot will cause my foot to move enough to make it act that way. At least it was in my case. Our parking lot at work has some rough spots and until I figured out my foot was actually moving I thought something was wrong with the accelerator. NOT.

[ckt]

I have a hessitation and then a surge back to acceleration, under light trottle from a complete stop. I have an O6' LBZ. The dealer has also looked at it and has nothing. I would love to have a fix for this problem.

[DIESELMAX403]

Kennedy,

Would you happen to know the part number for the pump pressure regulator? Are they OEM only or is their an aftermarket available. Depending on cost, I may just replace to eliminate one more possible cause for my problem.

Thanks,

DieselMax403