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Discussion Starter #1
Hi!

I did a search on a Cobalt that bucks upon acceleration and it brought me here. I have a 2009 manual Cobalt coupe with 48k miles. In May it started bucking and jerking while I was accelerating. At first it only did it when it was very hot & humid outside but since the weather has cooled in NY, it's still doing it. I've been taking mental notes on when it happens and discovered:

-It only does it when the car is running for a while, never in the morning. Mostly in the afternoon and on the way home, lots of stop & go traffic involved.

-It does it when I accelerate normally, when I give it a lot of gas and shift over 3,000, it's fine but I don't normally drive like that. Normal shift is between 2-3k RPM. I have been giving it more gas now but I know that's only a temp. solution.

-No engine light is on. I almost wish it was so someone could diagnose. Also had the air filter replaced and it didn't help. Put 93 octane in it last night and it seemed to help until later today when I was parked in a grocery store lot for 15 mins with the car running and then it started doing it again.

-Lucas Oil injector cleaner seems to help for about a day and then it goes back to doing it randomly. I can't afford to take it to Chevy unfortunately. Car is not under warranty. I do have an extended warranty but have never used it. Also, had the ignition recall fixed in Feb. so I'm not sure if this is related?

If anyone with a Cobalt or any other Chevy knows what could be causing it, I'd like to know so I can purchase the parts and have a private mechanic friend fix it. I only have a year to go and then it's paid off but no one will buy it if it's doing this and I would not want someone else to have to deal with it.

Thanks so much Chevy fans! My parents have been Chevy owners for 50+ years. I love my car and want it to get better :)
AmyM
 

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Even if the CEL isn't on you may still have a pending code. I'm leaning towards a dirty MAF sensor or maybe an intake leak. How does it idle?
 

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There is a possibility for it being a bad spark plug coil but i may be wrong.
 

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Thank you for replying to my thread. The car is fine when it's idling. Whether I'm at a light or parked with the car running there is no shaking.
When I left work today after the car had been parked for three and a half hours it drove fine until I had been driving for about 10 minutes and then the bucking started up again.
What is the MAF and are they generally expensive to purchase and install?
Thanks,
The MAF ( Mass Air Flow ) can be cleaned with MAF cleaner, it is mounted on the intake and measures how much air is flowing to the engine. Do you have a code reader?
 

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Discussion Starter #5
No but I know someone who does. But can I get a reading even if there is no check engine light on?
 

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Yes, you can check HO² readings, MAF & MAP, misfires and a lot of other things. No buy and replace parts just so you think you can save money. Sometimes even if you have to pay 80-100 dollars for a good diagnostic you can actually save money.
 
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Yeah, actually it's even possible to have the computer ignore a code for a while (for example, ignoring a P0420 because you cut out your cat) but it'll still be "pending" in memory. I bought a cheap $8 scanner on Amazon, and even it will let you view stored codes.
 
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