Ok everyone, I need a little help trying to diagnose a problem Im having... I have a few guesses, but would like solid info to point me in a general direction before I just go crazy...

Ok here's the deal, I have a 96' camaro LT1 in my 72' C10 (I know, I know, but its ALL GM harness, throttle body, stock engine, no tune, just some P/S Mids and a "CAI") now the truck starts just fine and idles cold fine probably 70% of the time.... The other times it will idle at 500 +/- and does so until the engine is shut down and restarted. (Occasionally it will clear up after warm) I thought it was just the "manual" idle adjustment, but when I turn up the idle screw then the idle is real high when warm or the next key cycle... I am guessing it is IAC or TPS?? Should I just look on Shoebox? Any good test procedures??

Mods: I apologize if this is in the wrong section...

Thank You!

 

Do not adjust the closed throttle stop to adjust idle. Thgat just screws up the IAC counts and makes it harder for the PCM to control the idle correctly. And it may mess up the TPS closed throttle reading and cause a code.

Figure out why its having the intermittent problem. The PCM has a table that elevates the cold start idle based on engine coolant temp. You may have an intermittent problem with the coolant temp sensor in the water pump housing.

 

I just had the same exact problem you have,guess what cured it. I had forgot to plug the Optispark vacuum hose back into the intake. When plugged back in the problem went away.