Surging at idle

[Anonymous]

I have a 92 ZR1 with a doug rippee chip & 3inch B&B. My car cycles the idle between 1000rpms & 1200 rpms. it is really annoying. Any suggestions?

[Anonymous]

It could be a number of things but I would check and clean the IAC valve on the side of the throttle body and would also clean the back of the throttle body plates.

[Anonymous]

Had a same problem once, it turned out to be oil in the hose and MAP sensor that was causing the surge at idle. I took it apart and cleaned it out with carb cleaner, it has worked fine ever since.

[Anonymous]

Thank you for a good starting place, where is the MAP located? I now have a new problem, I just came back from Vets at carlisle & the surging turned into a missing at idel. It also feels like the secondaries are not kicking in It has a real problem getting to 5000 rpms. I changed out the plugs & gapped them at .050. I have checked the vacuum it is okay How do I verify the secondary operation... (I know dumb question) Thanks for your help!!!

[Anonymous]

Map sensor is behind the intake covered by an aluminum plate. check the vacuum hose that connects to it. I bet you have oil in the line and the map can't do what its supposed to do.

[Anonymous]

Thank you for all of your help! it is a team like this that builds America. I will clean out the MAP & IAC tonight. Would the Map make the secondaries not function?

[Anonymous]

The map hose was cracked! I will keep you posted I think it is fixed now I will go hunting tonight.Thanks a million for your help!

[Anonymous]

My problem was 95% fixed by replacing the MAp hose. but my idle surge has again reappeared. My car will idle at 1500rpms when is is rolling then drop to 1000rpms when I stop completly it never goes lower than 1000rpms. At dead stop the idle will cycle between 1000 & 1200 rpms. I am going to remove the plentum this week end to replace the wires & look for anything out of place. Anyother suggestions from the gang out there in ZR1 world?Regards,

[Anonymous]

Possible other problem may be your IAC, it may be dirty and doesnot close all the way due to carbon build up. The IAC is located on the right side of the throttle body. This valve is what controls idle on the engine. Take it off and look for carbon build up. I hope this helps.

[Anonymous]

I have removed it and tried to close it manualy and it will not close. I pulled the plunger out of the housing and the spring came out. I put it back together it still surges. Should this IAC come appart easily?92 zr1

[Anonymous]

I don't think your supposed to be able to pull it apart. If you know anyone with a Tech 1A scanner, you could do a diagnostic test to see if it was operating through it's full range of motion. I don't want to send you off buying parts you really don't need but it sounds like your IAC is not working correctly. You didn't mention if you found oil in your MAP sensor. This caused the problem with mine. You mentioned that your vacuum hose was leaking, did you notice any oil inside of your MAP sensor. I wish I could help more, I know together we could figure it out.Good Luck