2005 Chevy Cobalt engine runs rough at idle

2005 CHEVROLET COBALT
76,000 MILES • 4 CYL • FWD • AUTOMATIC
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My 2005 cobalt runs very rough at idle. I had a code that idicated replace the knock sensor. Replaced this. Now I am changing the spark plugs and wires. The next thing that was suggested by an Auto Zone employee is changing the air filter and the fuel filter. I checked the air filter and it seems to be pretty clean. COuld my problem be it just needs a tune up. Just pulled one plug and the gap is way off and the plug is cooked.. In your opinion, could this be the problem? I am a 68 year old single woman trying to repair my own car (picture that)
Mar 27, 2010 at 12:04 PM
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GM-TECH
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Yes, replacing the spark plugs may help, but there may be a reason for the plug to be that bad. If you do not have over 100k miles, it should not be cooked, as you say. Fuel filter and air filter may not help. Need to find the cause for the plug problem. Have had a some of these engines with valve problems causing rough idle and burning spark plugs. Carbon in the valve causes compression problem in the effected cylinder.
www.JustAutoRepair.com
Apr 25, 2010 at 8:01 PM