High Idle in Park and Neutral

Tiny
OLDDODGETRUCK
  • MEMBER
  • 2001 DAEWOO NUBIRA
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 132,000 MILES
My 2001 Daewoo Nubira has had a high idle when cold and hot for about a month. When the engine is cold, like in the morning, I turn it on and the idle will jump to about 1600, sometimes it will drop to 900 sometimes it won't. I start driving and it's fine until I park it again, when I put it in park it will sometimes Idle at 900 but will usually jump somewhere in between 1600 and 2500, although it has gone as high as 3200. My first thought was the idle air control valve, so I took it out and the valve had some carbon buildup on the tip, but not what I would consider a lot. The hole had more so I used a cloth soaked in intake cleaner and cleaned them both. This didn't help, so after some research, I thought maybe a vacuum leak. I used propane to try to find the leak and while I was doing this I noticed two things. The first was the IACV made a grinding noise when the car was started, and when it was turned off. The second was after about 10 min of the engine idling at 900 I heard a pop and the idle immediately jumped to 1600. I don't know if either of those means anything but. Am I on the right track? What else could be broken?
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Tuesday, August 30th, 2016 AT 7:10 PM

4 Replies

Tiny
KEN
  • ADMIN
Yes the IAC motor making noise is not good, I would remove it and clean it first to see if that helps, if not replacement might be required.

Also I would service the mass air flow sensor, here is a couple guide that will help you

https://www.2carpros.com/articles/mass-air-flow-service

and

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Please let us know what you find so it will help others.

Best, Ken
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Monday, September 5th, 2016 AT 11:02 AM
Tiny
OLDDODGETRUCK
  • MEMBER
I don't think my car has a MAF sensor, but it does have a MAP sensor, could that be causing a problem?
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Wednesday, September 7th, 2016 AT 2:57 PM
Tiny
OLDDODGETRUCK
  • MEMBER
Figured it out, I took the throttle body off to take it apart, clean it, and replace the IACV, and when I was doing that I noticed the throttle plate didn't fit quite right. I took the plate off and put it on backwards and it fit a lot better (It appears as if the po did their own work as I've found several things like this). I cleaned everything, put the new IACV on, and the car idles great and runs alot better. It seems to have been a mixture of the IACV was sticking and the throttle plate was on upside down. Thanks for answering my question.
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Saturday, September 10th, 2016 AT 10:36 AM
Tiny
KEN
  • ADMIN
Good find, glad we could help, please use 2CarPros anytime, we are here to help.

Best, Ken
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Wednesday, September 14th, 2016 AT 4:30 PM

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