Maybe somebody can help. I recently replaced the engine in my 1992 Z28 350 with the same roller cam 5.7. It had immediate issues with its idle and found that it was not going int closed loop since it had a bad O2 sensor. That was replaced and initially fixed the problem. However, it started it again. It will run as high as 1500 rpm when its hot at idle or plummit to around 500 (or lower and stall). I replaced the idle air control motor and valve, but did not change. Should I check the vacuum hoses or is it more serious such as the ECM?? I was also considering the possibility of bad gas (every gas station where I live has 10% crap ethanol which has already damaged my new Delco fuel pump!!!). Any info would be beneficial.

 

Oh well. As it is, the car is running fine (enough). The idle is more consistent with premium gas and runs better during cooler environmental temps (<90F). It has not stalled in quite a while (as i said before the idle can go either way), but those are the times that I've been stuck in traffic over an hour. Im in the process of purchasing a "work" car and using the camaro as a weekend toy. I wonder, if anybody else has had problems "chasing idle."

 

you follow the proper adjustment procedure on the IAC when you installed the new one? Did you clean the throttle plate/bore, and IAC passages, and replace the gaskets? Go to www.thirdgen.org and search for the tech article on how to properly adjust the IAC and TPS.

 

also the proper term is hunting idle FYI

 

The idle air control valve as well as motor have been properly replaced. This was actually done first after the engine replacement since I was having issue with the surging/idle. It ended up being the O2 sensor not going to closed loop. Since then that has been replaced, and temp. corrected the problem. However, the question posted remains the issue. The throttle plate has been thoughly cleaned. The replacement engine is not a rebuilt but actually a original roller cam 350 straight from GM (3 year/36,000 warranty), the only thing that is not new under the hood is the TPI wiring harness or ECM. No codes show up as faulty. The injectors are working fine as well. I appreciate the input however and will adjust the IAC and TPS if required. Thanks.