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Discussion Starter #1
2009 with about 80,000 miles.

Engine light will sporadically come on and off and has once started flashing which was when the shaking was worse. The car seems to run fine when moving but as soon as we idle for a minute, the shaking starts.

Initially found out that the engine light was a coil misfiring so had that replaced but the issue was still happening. Couldn't find any other engine codes besides an EVAP leak, but was told that this wouldn't be causing the issue.

Any ideas?
 

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Sounds like a problem I had when my Cobalt was new. They told me it had particles in the camshaft. Dunno exactly what they meant by that, but maybe have that checked out?
 

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Dirty throttle body would give you those symptoms.
 

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So I took the car to the dealership for another opinion and they are stating that possibly the valves need to be replaced. At least one valve definitely where the misfire is occurring and potentially more if they are causing issues.

Does that sound like it would definitely be the problem. If so, what would cause an issue like this on a car with such low miles?
 

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Did they do a compression test?

Did you have a look inside the throttle body?

When is the last time you changed the air filter?

Maybe you just need spark plugs, do the cheap stuff first before paying thousands os dollars to the dealer for something you probably don't need. Some of these engines go 600,000 miles with the same valves.
 

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I was trying to read up on the throttle body cleaning and have seen that it can cause the idling, but most cases it has not thrown the engine light for a misfire.
 

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If the throttle body gets dirty enough you will get all sorts of codes including misfire codes.
 

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Yeah, just start with pulling the throttle body off and seeing if it could use a cleaning. If it does, and cleaning it fixes the problem, then you didn't spend big money just diagnosing it. Otherwise, move onto the other stuff Coby suggested. I wouldn't let the dealership pull apart the engine until you've exhausted all the other, cheaper potential fixes.
 

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you're looking at a couple grand easily at the dealership! They won't do a valve job there, more than likely they will replace the entire head. That being said, I've experienced the same problem as you and it was just a leak in my intake system. Check all your vacuum lines and intake components. For me a coupler slipped off, I popped it back on and viola! It was fixed.
 
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