High idle around 2500rpms

COBALT06

MEMBER
2006 CHEVROLET COBALT
2.4L
4 CYL
FWD
MANUAL
120,000 MILES

My car has a high idle around 2500rpms. It all started when I took the throttle body off to clean. When I put it back on my idle was high. I've taken it to 2 different garages and still cant figure out what's wrong. I've bought a brand new throttle body and had a scan tool to try to relearn idle but still high. There is no vaccum leaks and the MAP and MAF sensors are reading good. Any ideas? The throttle body is the same on my car as it is for a Pontiac G6, so we noticed when you shut the Pontiac G6 off the butterfly valve on throttle body closes all the way. When we shut my car off, the butterfly valve stays partially open. Both garages have ran out of ideas. Please help with suggestions. Thanks

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Is the check engine light on?

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Wednesday, February 24th, 2016 AT 4:02 PM

COBALT06

MEMBER
2 POSTS

Sorry took so long to respond. I pretty much gave up on the car b/c everyone was out of ideas. But I still have the car and still have the same issue. Except now when I start it and its in neutral it idles normal. Until I touch the gas. Then same thing. Idle shoots up. And it feels like I have cruise control on while driving. And yes check engine light is on