2003 Pontiac Grand Am Low Idle

2003 PONTIAC GRAND AM
127,634 MILES • 4 CYL • 2WD • AUTOMATIC
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IVORYT
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  • 1 POST
For the last month or so, my car has been misfiring when idling. It seems to run fine when accelerating. I've replaced the spark plugs, the coil housing, the boots... We even tried turning up theidle.

I have noticed that as the car warms up, the RPMs when idling drop from about 1000 when I first start it to only 500, and that's where the problems begins. (When running, the RPM guage stays between 1000 and 2000, but it goes steadily down as I decelerate.)

I had our local mechanic turn the service light off last week. He said it was reading "multiple engine misfires" -- and I see the stupid light is back on today! What's going on?
Feb 24, 2010 at 6:40 AM
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RASMATAZ
  • ✓ASE Certified Mechanic
  • 75,992 POSTS
  • ASE Certified Mechanic
Engine running rough or misfiring can be cause by the following:

1.Defective spark plug.
2.Inadequate spark/coil,defective spark plug wire.
3.Lack of compression
4.False air leakage.
5.Faulty fuel injectors.
6.Insufficient fuel pressure.
7.Contaminated fuel.
8.EGR valve that is leaking.
9.Oxygen sensors.
10.Idle air control valve
Feb 24, 2010 at 7:14 AM
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