Rough Idle

RANDYOFPA

MEMBER
2005 PONTIAC GRAND AM
4 CYL
FWD
AUTOMATIC
86,950 MILES

I have a 2005 pontiac Grand am 4 cylinder and it often has a rough idle / 86000 miles on the car any suggestions

Sunday, November 21st, 2010 AT 2:58 PM

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Can you describe the rough idle in more details?
Idling speed too low? Misfiring?

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Sunday, November 21st, 2010 AT 3:59 PM

RASMATAZ

MECHANIC
75,992 POSTS

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

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Sunday, November 21st, 2010 AT 4:00 PM

RANDYOFPA

MEMBER
2 POSTS

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

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Sunday, November 21st, 2010 AT 6:27 PM