# Chevy Cobalt Engine issue **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** cobalt, engines\ **Created:** [May 22, 2009, 9:56pm UTC](https://community.cartalk.com/t/chevy-cobalt-engine-issue/30848 "2009-05-22T21:56:57Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Mortus](https://avatars.discourse-cdn.com/v4/letter/m/a9adbd/32.png) [@Mortus](https://community.cartalk.com/u/Mortus)\ **Post date:** [May 22, 2009, 9:56pm UTC](https://community.cartalk.com/t/chevy-cobalt-engine-issue/30848/1 "2009-05-22T21:56:57Z")
Ok, little details before hand. 2006 Chevy Cobalt LS 78k miles (if that matters) Basically I’ll try to describe the issue and hopefully someone picks up on it. Whenever I am either coasting, coming to a stop, or not moving, my RPM’s start bouncing. They bounce from about 900 to 400ish, and everytime it hits 400 the engine shakes. If I hit the gas before it bounces up to 900, it’ll stall. If I start coasting after a stop while it’s bouncing, it will stall. And sometimes it will take 3 or 4 tries to get it to start (this is rare, only once a month or so). Any tips? ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [May 22, 2009, 10:10pm UTC](https://community.cartalk.com/t/chevy-cobalt-engine-issue/30848/2 "2009-05-22T22:10:39Z")
For the “bouncing idle”, you could have a disconnected vacuum hose. Or, the Mass Air Flow sensor (MAF) could be dirty. Or, your Idle Air Control (IAC) could be bad. Your Check Engine Light (CEL) is not lit up? ---
**Author:** ![Mortus](https://avatars.discourse-cdn.com/v4/letter/m/a9adbd/32.png) [@Mortus](https://community.cartalk.com/u/Mortus)\ **Post date:** [May 22, 2009, 11:00pm UTC](https://community.cartalk.com/t/chevy-cobalt-engine-issue/30848/3 "2009-05-22T23:00:49Z")
Nope, no check engine light.