So I've got an 88 Iroc-Z with a 350 TPI setup. Just finished putting it all together, and the car runs great....sometimes. Usually when its cold, it runs without incident. When it starts to warm up, it will switch in an out of open/closed loop (I know this from the Dynamic EBL hardware I purchased) causing the idle to jump up and down between 1000 and 500 rpms. I found this is due to the O2 sensor cutting in and out, usually when my foot is off the throttle. Odd, it will read 0 mV at 0% throttle, but jumps right up to 485 mV or more when you crack the throttle the slightest bit.

Also, the car will stall at times while sitting in traffic. At first, I thought the TCC wasn't functioning, but why would that be temperature specific? It runs great when its cold, but stalls when it warms up. It does this even when the O2 sensor isn't acting up.

Any Ideas?

 

check your fan, if its mechanical check if its locked up, if its electrical then check if the fuse is bad, or if its disconnected, also check your lower radiator hose for cracks, leaks, or eroded, and make sure your getting enough airflow through your radiator.

When your sitting in traffic, and the car heats up the fan will go on to cool it down, because the radiator isnt sucking in any air.

Hope this helps..