dead accelerator pedal

[carco]

Sometimes, about every 15-30 miles, usually after a decel or take off from a stop the engine will not pull. Very slowly gains speed like a very soft take off even if you push pedal to floor. Usually as pedal about reaches the floor the engine will begin to take off if the pedal is not eased up quickly enough the engine goes like a full throttle start. Next 10 miles may be normal. NO codes!!, yet.
2004.5 LLY with or w/out Edge does it more often with Edge.
Has anyone run into this problem?? TIA

[carco]

I now know today that the accel pedal voltages are ok and all three signals move correctly.
I know #7 injector balance rate is a little high @ idle +7.2 ave. others are -1.4 to +2.4.
I know the desired and actual fuel rates follow each other closely even when the pedal is dead or non acceleration is occurring.
I know that fuel rate (mm3) follows APP%, pedal percent fairly closely even when non acceleration occurs.
But so far have found nothing out of normal.

[DmaxMaverick]

Remove (physically, not just deprogram) your Edge module and try to repeat the problem.

[carco]

The Edge is removed and problem still occurs.

[JohnC]

I know that fuel rate (mm3) follows APP%, pedal percent fairly closely even when non acceleration occurs.

It is unlikely that this is true. If the fuel was there, the engine would accelerate. More likely, the commanded fuel rate follows but there's no fuel being injected. How about fuel filter restriction? (You'd expect a code, though...)

[DmaxMaverick]

(assuming new air/fuel filters)
Sounds like the turbine vane servo. You'll need a Tech II to command it, or relearn the throw positioning. Not uncommon on early LLY's. They can become fouled with soot making them sluggish at throw extremes (like a deceleration, then take off from a stop). A test and full throw command usually clears them up. Sometimes they set a code, sometimes not. Often, it will set a DTC, but not set the SES (depends on how bad it is, and the frequency).

The use of power adding programmers tend to exaggerate the condition. The Edge modules are notorious for overfueling (smoky) before the turbo wakes up, which causes excess sooting.

[carco]

DMav, we will chk out the turbo etc. We did some research today in spare time and turbo has peaked my interest, but no research there yet. No CEL nor codes set, other than mass air which has been set since air filter change to 06 unit. Yes, exhaust is somewhat sooty, worse since 06 air box, I need to get update flash.
If we have time tomorrow we will chk turbo. Thanks!

[DmaxMaverick]

If you are getting MAF code(s), the likelihood is high you had an overfueling condition. The PCM calibration update corrects the MAF dynamic translation to read correct with the internal airflow of the new filter assy, which should cure the MAF code. And perhaps, prevent issues in the future. Incorrect MAF translation in addition to power programming can lead to an off-timed EGR function and low power overfueling (during turbo lag). All this makes for an excessive amount of soot. The MAF error could be the cause of low/no power at take-off, in itself. The PCM won't allow excessive fuel during acceleration under the charge air envelope (before the turbo wakes up). It may be as simple as that, especially since the condition is intermittent. The most difficult diagnosing issues like this is determining the "cause <-> effect" direction. In this case, it could go either way. Normally, addressing one issue will cure the other. I suggest addressing the MAF issue first. The other problems may fall away after that.

[carco]

The MAF codes are due to the air box switch out to an 06 air filter and box assy.
Yes, it does run somewhat rich at least going by exh outlet smoke.
Yes, hopefully recal will get rid of the MAF code.
EGR is gone!
No time to look today try tomorrow.

[Kennedy]

If you run the 06 air box there is a factory programming update to compensate. I'd suggest this or a good custom tune based on this before pulling your hair out.