[thomjp73]

Hoping someone can help me out there with this problem I'm having.

I have a 2008 G6 GT Sedan Automatic with the 3.5L V6. For about a month now I've noticed the engine will cut out almost like it's misfiring during acceleration. The check engine light does not come on at all when it is doing this and no codes came up in the system during my inspection (which was after the problem started). I took it into the dealership, since it still has warranty on it, but they said it was because some sensors were covered in carbon buildup, and that it wouldn't be covered under warranty (general maintenance). According to their paperwork, all they did was drive it around a little bit and then run it through the system to see if there were any codes.

I don't know everything about a car, but I would figure if a sensor has carbon buildup on it, it should throw a code in the system. After I got it out of the dealership, and not paying the 250 dollars they wanted to clean the carbon buildup out, I have done some of my own investigating. Not realizing it at the time, back in April I took it in for almost the same exact thing, though not as bad, and they did work on the throttle body. I didn't notice it again until it started about a month ago.

Here's what I've tried to get rid of it...
1. Ran Berryman's B-12 through it multiple times to clear out possible moisture in gas (no effect)
2. Ran premium gas through it (no effect)

Here are the full symptoms I've noticed...
1. Only happens during gradual/normal acceleration, if I put the pedal down hard it doesn't do it.
2. Only happens between 1-2k RPM

I really want to get this fixed so I can try to get rid of the car soon...I'm trying to reduce my monthly payments, so any advice/help you could give me would be greatly appreciated.

 

[slls]

You may have a EGR problem, carbon under the pintle. Too be sure you have EGR look at your emissions decal under the hood, all the emission systems are listed.

 

[Shadow662]

Not to sound like I know anything but I had a 03 Impala with 3.4L that did the same thing needed a intake manifold gasket. Although maybe not the recommended way to check using starting fluid around the manifold gasket you will tell if you have a gasket problem. This can also be done around the throttle body since they had worked on it before maybe they fudged the gasket during re-install. Just have to do it with the intake piping on. Should cause high RPM till the starter fluid is burnt off. Don't use excessive amounts can cause damage to pistons.

 

[care9012]

Did you have the dealer check the ignition system?

Mine had a similar problem to what you described. Ended up being a cracked insulator on the number 1 cylinder spark plug. I have read on here that also people have had things like the spark plug wire or ignition coil go bad.

 

[KyleG]

When you say cut out, do you mean it actually stops? Like you have to start your car again?