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Discussion Starter #1
I noticed this morning when I came to the first traffic light that my car was doing a slight shake....rpm's were about .8k... It felt like a motor mount might be loose or maybe a cylinder wasn't firing quite right..I think I noticed sluggishness with it in 5th gear at speeds below 50mph as well as when idling at a stop. We had a lot of rain here last night but I drove it for 30+ miles and still have the same symptoms.

Any ideas? TIA
 

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If it shakes at stop lights it's most likely a mount going bad, but wouldn't account for the sluggish response other than it's a low powered 4 cyl. in 5th! Check your upper engine mount and two lower trans mounts for signs of cracking in the rubber.
 

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Misfire will give a code. When is the last time you clean the throttle body?
 

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Discussion Starter #4
Misfire will give a code. When is the last time you clean the throttle body?
I haven't cleaned it yet Coby. I can have a look at it this weekend and let you know. I scheduled service for Monday.

It wasn't doing it yesterday...just started this morning. Not sure but it almost feels like the shaking is forward to back...rather than side to side.

I was thinking a coil pack or bad wire somewhere...we had a heavy downpour last night that lasted a few hours...I think that it should have dried out on the way to work though..so maybe not.
 

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Moisture will swell the gunk that accumulates around the butterfly. If humidity levels go down it will start to work better. Just take the intake off and if you have any black gunk you know it might be your problem.
 

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Discussion Starter #6
Moisture will swell the hunk that accumulates around the butterfly. If humidity levels go down it will start to work better. Just take the intake off and if you have any black gunk you know it might be your problem.
Thanks Coby,

I cleaned around the butterfly and into the throttle body w/throttle body cleaner and a clean rag. It wasn't too dirty....also cleaned the MAF w/MAF cleaner....but no change ...Leaving work last night I checked the air filter...(it was pretty dirty) afterwhich the CEL came on and stayed on.

Stopped by the dealer to pick up some parts and they said I could leave the car there.

I'll let you know what it was.
 

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Discussion Starter #7
The dealer replaced the cam actuator and cleaned the fuel injectors. Runs very smoooooooth again... :bigsmile:
 

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Cam actuator would set a code as soon as it would fall out of spec. Hope this work was done on warranty. Dirty injectors are a most probable cause.
 

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Discussion Starter #9
Cam actuator would set a code as soon as it would fall out of spec. Hope this work was done on warranty. Dirty injectors are a most probable cause.
Coby,

Replacing the actuator was on their dime. I may have picked up some bad gas a few weeks ago. It's running better now than it's run in a while. My gas mileage hasn't been as good as it's been in previous summers...hoping I see some improvement here as well.

Thanks!!
 

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Hey keegs

So glad to see that your Cobalt was repaired...and under warranty! Please remember to send us a message if you even need any assistance.

Jackie
Chevrolet Customer Care
 

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Discussion Starter #11 (Edited)
Hey keegs

So glad to see that your Cobalt was repaired...and under warranty! Please remember to send us a message if you even need any assistance.

Jackie
Chevrolet Customer Care
Thanks Jackie...I noticed a slight shimmy again a few days after getting the car back. I put some Marvel Mystery Oil in the gas tank...not much ..just a few ounces ..and the shimmy stopped..not sure if there's correlation though.. but for extra measure, when the tank ran close to dry, I put a bottle of Techron in and filled it up. It's been fine since. :bigsmile:
 
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