Throttle problem

[PitchblackC3]

truck is a 2001 C3 6.0L 4L65e.
I am having a problem with the ETC. If the TPS reaches 85-90% the reduced engine power mode is triggered and code p1518 sets. Throttle works normally unless over 85-90% throttle is requested. I can make this code set with just the key on and the engine not running. This makes me think the problem lies with the TAC not the MAF or related.

The root of this problem I'm sure is that this is a 2001 DBW truck that is running with a 2003 DBW throttle body and TAC. The pedals are the same. I have tried swapping pedals and TACs from running trucks with the same results. Could there be something in the tune 2001 DBW vs. 2003 DBW that would cause this?
This truck has a mild tune, and I reverted it back to stock with the same results.
Any ideas?

I guess I should try swapping throttle bodies as well.

[PitchblackC3]

I think I may have found something, the pedal position only goes up to about 25% even when the throttle is approachinng 85%

*edit* nevermind appearantly that is normal

[PitchblackC3]

Looking for input.

[kamikazematt]

have you looked into the etc limits in the tune?

[PitchblackC3]

have you looked into the etc limits in the tune?

I tried comparing a stock 03 6.0 tune to mine. Made some changes which had no effect.
Which tables specifically? Where would I find the ETC limits? The only thing I see is under torque management.

[kamikazematt]

i thought that was it, but i just found under engine diag/general there is a table labeled calc airflow. basically if the maf reads more on any cell than what is calced out in there it will put it into the reduced power mode. might wanna play with them with caution as it is a failsafe for your etc going bad.

[PitchblackC3]

I was thinking it's not MAF related since it will set the reduced engine power even without the engine running.

Is it possible there is a OS difference between the 01 and 03?
Just seems odd that it will work until the tps hits hits 85% not sure what to make of that.

[kamikazematt]

hmm im not to sure then.

[PitchblackC3]

Bump for the day crew. Anybody know of a problem running a 2003 TAC and TB on a 2001?

[PitchblackC3]

I went out and turned the key on and moved the throttle blade by hand and even at 100% the code never sets. Looks like I am dealing with something on the TAC or pedal side.

[PitchblackC3]

I tried a different PCM in the truck with no luck, it and the original are both 0411s.
I took a PCM from a 2003 Tahoe SERV NO 12582605 HDWR NO 12580786 and plugged in the blue connector only. Key on--- I get full 100% from the TPS with no code.

So there is something in the 03+ PCM whether it be a physical difference or tune related.

Now I wonder if it is possible to upload my 2001 tune to a 2003 PCM and run it from it. If it is software related this won't work, but if it is a PCM hardware difference this should fix the problem.

[PitchblackC3]

Anybody have information about the DBW functions between the BLUE/RED pcms and the BLUE/GREEN ones?
Is it a physical difference or tune only?
Seems like I read something about drivers being different on the pcms, but now I can't find that again.

[PitchblackC3]

Well, I solved this problem by switching to a 2003 PCM. I had to use a 2003 LQ4 file with a 4L60e segment swap. A few pins had to be moved to convert the RED plug to GREEN, but not many.
Running great now with 100% throttle. The PCM, IP and BCM are communicating flawlessly.
I kept all my 2001 parts to switch back to in case I want to go with a 90 or 87mm TB in the future.