Hello group,

A couple years ago I swapped in a stock LS3 with GM controller in to my '64 Corvette. Car runs great 95% of the time, but I've been struggling with troubleshooting the cause of P2176 (Throttle Actuator Control System - Idle Position not Learned) getting set. Majority of the time the car starts up great and idles no problem. I've done the throttle learn and idle learn procedure many times. Occasionally when restarting a hot engine the code will set and the engine runs rough and is undrivable. If I clear the code and key cycle, the engine fires right up and runs with no problem. All I've been doing to "fix" the problem is clearing the code.

Over time I've figured out this code only gets set on a hot restart. Never from a cold start or if the engine has cooled down a bit. So like stopping at a gas station and then restarting is a good example of when this code will set.

So I'm thinking something is setting the code when it is hot. Throttle body maybe? The throttle body is a new stock GM part and I've already tried replacing it with another new stock part.

Any other suggestions?



Thanks,
Patrick

 

Let me bump my own post in case someone can help me out

Thanks,
Patrick

 

Hi Patrick were you able to resolve this? I am going through the same exact thing with my LS3 swap. I also changed the Throttle body and nothing. Please let me know, thanks

 

Hey there, sorry to hear you are experiencing the same problem. I haven't figured out the root cause yet and my car will be garaged for most of the winter so no trouble shooting for my anytime soon. It's got to be something getting too hot or a bad wiring connection somewhere. Or maybe something in the cal. Who did your engine cal?

 

So obviously this is Drive-By-Wire (DBW) with an electronic pedal. Do you also have a TAC module? (Sorry I forget is this in not used with newer ECMS.)
I have also struggled with DBW on some swaps, but never received that code. Hopefully someone has this knowledge and ideas for you.

 

Yep, DBW system. All of that has been working just fine. I don't recall a TAC module in my build. Pretty sure the pedal connects directly with the engine controller. My setup basically mimics an '08 Corvette.

Yeah, I really hope someone has a good suggestion. This has been frustrating.

Patrick

 

I hear you. I have two other LS3 cars and have never had an issue. All with PSI Harness. This one i bought done so I am sorting out these little issues.

 

The 2008 non-supercharged Corvette had a E38 ECM. (Doesn't need a TAC). The super-charged Corvette used the E67 ECM.
The 2008 had a TB part # 12570790
The 2009 had a different TB part # 12605109
From a Corvette forum post, they "almost" interchange but not really, end up throwing codes.
So maybe double check that you have the correct one for your ECM's part number. From what I can gather the 2008 and 2009 ECM had different part numbers.

 

I’m curious if you made progress on solving this. I’m running into a similar situation with an LS9 swap. Thanks.

 

Pulled my car out of winter storage awhile back, still having the same fault code issue. Looks like a couple others saw the same thing, but I've not heard of a root cause yet. Anyone else have any thoughts?