Rough Idle

[stitus]

I have an 84 turbo Z that recently started running very poorly. It starts up fine and idles completely smooth, but after roughly 2 min it starts running rich and starts missing. The idle will drop to about 400rpm then shoot up to 1500 and smooth out until it idles back down again. If I take it out and drive it, it dies when I stop, and bucks like crazy at part throttle. However it accelerates and runs perfectly when I stuff my foot into it. I recently had the head off and broke the 02 sensor, which is the only code the computer is showing. However it still ran and idled fine for over a month with the broken 02. I've changed out the coolant temp sending unit and the AIS motor as well. When I unplug the vacuum line to the regulator it idles perfectly. Fuel pressure is normal, and I swapped in different injectors with the same results. What else would cause it to run rich?

[boboli]

My guess would be your O2. years ago I had put a new 3 wire in my omni, did the T2 conversion and also the O2 upgrade, and it ran poorly and didn't pass smog. On my a/f gauge there was no movement, it stayed nearly solid in the middle. I didn't believe it was the O2, since it was new,even though car sat for 6 yrs, but everyone told me that would be the problem. Sure enough i got under the car and the rats that had messed up the engine harness had chewed the heater wire on the O2 and it would never warm up with my 3" exh. I did the 4 wire conversion, mainly because these O2's are a lot easier to purchase where i live, and it worked great. Passed emissions with flying colors and gauge moves now.
If you still have the O2 code i would try changing the sensor first. You may want to try either a 3 or 4 wire O2 upgrade as well.
PS i don't think the computer uses the info from the O2 during wide open throttle so that may be why it seems to work fine.

[stitus]

O2 solved the problem!