High Idle

[Lou M]

OK. I checked the message board to see if anyone else had this issue and cannnot find anything. So this is what I have:

When I start the car, the engine runs up to about 2,000 rpm and sets there. I will tap the accellerator pedal and nothing changes. It just runs up then settles back to 2K.

I put it in gear and drive away.(Of course it does jump a little due to the high revs). When I come to a stop and put the car back into park the idle is back to where it should be.

No "Check Engine" light. But I did go to the local parts store and used one of their code readers. No code. I was told by the salesperson that there wouldn't be a code because the Check Engine light wasn't on (???). When I started the car after disconnecting the code reader it was fine (??). Then the same high rev issue came back on the next start.

I reset the computer by disconnecting the battery and waiting then reconnecting. On the first restart it was ok. Then it started doing it again.

I was thinking that it might be the IAC. But when I search for that I see rough idle issues as opposed to high revs at idle.

Any ideas???

Oh yeah, 2002 ST, 75K miles.

Thanks

Lou...

 

[TRACket Paul]

Clean the IAC. It only takes a few minutes to find out. Inspect for sticking throttle cable/linkage and try lubricating it.

 

[Dre L]

More than likely you have dirty stick parts if you've never cleaned them. Clean the IAC, throttle body intake, and throttle linkage with a can of gumout (Fuel injected engine safe) Air intake and throttle body cleaner. It may be so bad a replacement of the IAC is warranted($50)



Lubricate the throttle linkage (the cable, the spring) with a little grease. I usually leave a dollop on the spring, and one on the cable hole at the accellerator cable sheath.



If you have a way to check the throttle position sensor, coolant temp, and coolant temp sensor, do it.



There is an idle set screw which manually sets the throttle position, although it should not move on its own, so there may be a TPS issue. Check the screw, it is under the throttle (by the throttle body intake), and the throttle rests on it. If you screw it in, idle goes up, if you screw it out, idle goes down. Screw with it too much, you screw things up.



I have a scangauge which gives me feedback to work with, so I can screw with things.



If your CTS is screwed up, then it won't think the engine is warming up, and the computer will increase the idle. Make sure your temperature is going up.



There are projects and/or postings on this site for everything mentioned here. Do a search.



Good luck.

 

[Todd Z]

Check the common vaccume elbow, IF cracked slightly, that can happen....

Todd Z