Ok, I need some help here. Nobody can tell me exactly what is wrong with my 07' cobalt. The idle jumps when I step on the clutch to 3000 RPM and I have to play with the clutch and gas pedal to bring the RPM down to normal to stop so I don't blow my engine. The shop says its misfiring on the 4th cylinder and my o2 sensors are reading bad. I've cleaned my throttle body recently and changed the spark plugs about a year ago. I don't know I'd it's a bad injector or a vacuum leak or just a dirty IDLE AIR CONTROL VALVE. It has about 132000 miles on it and I keep all Maintence up on it regularly. So any insight would be great! Thanks!
I looked into the general information I have available to me, and wasn't able to find any troubleshooting for the condition you're describing. If you were to decide on working with a dealership, please let me know through a private message as I would like to be sure to follow up with them and with you to see how things go.
Have a great holiday weekend,
GM Customer Service
This is probably an obviously stupid question, but you are taking your foot off the gas when you put the clutch in right?
When you take your foot off the gas, do you start to engine brake, or does it just keep accelerating? This will be most noticeable in first gear...get going to 4-5000rpm and take your foot off the gas. You'll either slowly slow, or jolt forward and back...it'll be really obvious.
As soon as go to stop from whatever gear I'm in, say 3rd and braking from 35 mph. As soon as I press on my clutch it's jumps up to 3000 rpm. And no, my foot is not on the gas. Lol been driving stick over 10 years. But it doesn't jump when I'm going up in gears only when I step on the clutch to stop. And if the engine is really cold still, it won't do it.
Maybe your throttle plate is sticking. Try taping the gas pedal next time to see if it releases. Maybe you moved the plate sideways a little when you cleaned the throttle body.
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