High searching Idle
 

Well, just moved #473.. drove it two weeks ago, no issues, ran beautifully. When I started it to move it today, the car sounded like it backfired immediately upon start. But shut down instantly. I cranked it again and it started right up. Took it out for a spin around the block and it ran great, BUT, the idle is now at 1250, not 750 like it is supposed to be.

Pulled into shop and looked around the engine. The PCV plug at the back of the engine was partially popped off. Likely due to the backfire. Pushed it back down and the idle dropped to 1150.

Pulled the IAC and it was clean. Put it back in and hooked up Moates interface and launched TunerPro RT. Started the engine and the IAC is locked at 0. Engine is hunting for idle. My guess is that the IAC cratered.

Input welcomed. Any way to check the IAC before I look for a new one?

Are these IAC's available still? Jerry, do you have one for a '91?

Thanks Guys...

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Re: High searching Idle
 

I would check MAP sensor vacuum line (unless when you said PCV line partially popped off, you meant MAP sensor vacuum line).

Re: High searching Idle
 

Map sensor line is good. The double PCV plug was not fully seated on the PCV valves..

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Re: High searching Idle
 

Have u tie wrapped it down?

Re: High searching Idle
 

Dominic, it's very tight. I'll check again. When I lost the MAP hose connection about 18 months ago, the car wouldn't hold an idle and was almost undrivable. The car drives beautifully, but now has high idle and it "hunts" about 100 rpm up and down..

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Re: High searching Idle
 

It's possible the backfield pushed another vacuum hose loose under the plenum. If it is indeed a vacuum leak, it's a very slight one..

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Re: High searching Idle
 

Just about every vacuum connection on my motor is tie wrapped. I hate vacuum leaks no matter how slight.
When I got my first ZR, it ran great but had a slight hunt. Marc looked at it and said PCV. He was right.

Re: High searching Idle
 

Ok, will tie wrap the PCV connection.. I've got a new one too, might just change it out..

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Re: High searching Idle
 

Not sure what I can try wrap.. hose clamps on all single pipe connections. I'll put the new o e on and see if that resolves it.[ATTACH][ATTACH]

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Re: High searching Idle
 

Tie wrap the top and bottom halves of the F to each other.