Rough Idle

PONTIAC GRAND AM
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SCOOP520
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I have a 2000 Pontiac Grand Am 2.4L 145,000 miles that has idle problems. When first starting off while the engine is still warming up the engine idle is fine when I come to a stop. When the engine is warmed up however, the idle becomes very rough when stopped in drive. Throwing the car into neutral smoothes it out. Car accelerates fine and runs smooth. Have replaced spark plugs, boots, and coils. No luck. No check engine lights coming on. Any ideas?
Sep 14, 2007 at 7:16 PM
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RASMATAZ
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Hello,

This sounds like it can be one of two things first is the MAF sensor is off a little not triggering the check engine light. Next would be the engine coolant temperature sensor has gone bad. Here are tow guides to help us get the problem fixed.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

and

https://www.2carpros.com/articles/engine-vibration-at-idle

and

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Please run down these guides and diagrams and report back

Cheers
Sep 14, 2007 at 8:44 PM
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SCOOP520
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I had the OBD2 system scanned for codes. No codes came up during the scan so I replaced the MAF sensor and the car has never run better :) thanks for the tip.
Sep 15, 2007 at 11:14 AM
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RASMATAZ
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Use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers
Sep 15, 2007 at 4:53 PM