rough Idle

2005 PONTIAC GRAND AM
86,950 MILES • 4 CYL • FWD • AUTOMATIC
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RANDYOFPA
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I have a 2005 pontiac Grand am 4 cylinder and it often has a rough idle / 86000 miles on the car any suggestions
Nov 21, 2010 at 2:58 PM
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KHLOW2008
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Can you describe the rough idle in more details?
Idling speed too low? Misfiring?
Nov 21, 2010 at 3:59 PM
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RASMATAZ
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Engine running rough or misfiring can be cause by the following:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

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.Throttle position sensor.
11.Manifold absolute pressure sensor
12.Mass Airflow Sensor
13 Idle air control valve
Nov 21, 2010 at 4:00 PM
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RANDYOFPA
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Thanks for asking it feels like a very slight surge that transfers vibration to the dash board / the RPMs seem to be stable , and it happens inconsistently / I had this same problem last Fall and it seemed to disappear over the summer months / it only happens when the car is stopped and in gear / sometimes the vibration is heavier than other times / I understand when the air conditioning compressor cycles it changes the smooth Idle but it happens without the compressor cycling / I drive the care 50 miles a day and about 40 miles are highway driving where I keep the speed at 55 - 65 MPH, I don’t believe I could have a dirty fuel system
Nov 21, 2010 at 6:27 PM