May want to try ...

cleaning the throttle bodies.
MaxDoc

 

You might have a bad connection on the Idle air control valve. Look at the back of your plenum on the drivers side and check the yellow plug for corrosion. I've had this problem in the past.

 

No Subject

Post Edited (May 18, 5:09am)

 

Well...

I think I finally got mine solved. Last night I: Synchronized the throttle bodies ( I found an easy way), adjusted the throttle cable, then the TPS, then the idle on the AAV. All of last night, and on the way in to work this morning It held the idle at about 850-875 rpm, when the fan kicks on (electric) it pulls it down to about 790. But now it is smooth.

Eric

 

Where is the tps, throttle position sensor? located? Do i check and clean the connection or just replace the tps? Where is the air regulator located?
I'm gonna clean the throttle bodies first then go to the other 2 if that doesnt fix it. I cant find my repair manual..I should keep in it the car.

 

where is the manual: Online Nissan 300ZX service manual

 

There's lots of info on these things if you search.

 

If you disconnect it look with conzult it will show around 50% opening @ operating temp. Mine jumps up to around 1500-1600 rpm @ 50% opening. Operating temp should be 15% of the IACV. 1800-2000 might be a bit high. That connection does get corroded Though which can contribute to a high idle.

 

this sounds odd, and I am not by any means a mechanic, but mine started randomly idling high for a while. I have a decent mechanic and we went through the throttle bodies, etc., didn't change anything.

I later realized that one of the mufflers had holes in it. Replacing the one with holes caused an instant return to the proper idle. I am assuming, and don't really know, that the lack of proper back pressure was screwing with the car's brains.

That's for what it's worth. Good luck.

Mine is a 91 NA, no TTop. I love it.