Rough Idle

[Conjee]

2003 Galant 4 Cyl. I changed my spark plugs and my car is idling rough when warm. When my car is still cold it idles fine, as it gets warmer to normal operating temperature the idling gets pretty bad. I feel the car shaking and some squeaky noise are coming from under the hood. After a while of driving (about 40 mins or so) the car idles fine with no squeaky noise. The RPM meter is at about 700. When I shift my car to neutral at stop lights, the whole problem goes away, no more rough idle and squeaky noises. Seems like when my RPM goes up by about 50 when my car is set on neutral, my car is fine. Wonder if I should adjust the idle rpm? Any help as what could be the problem and how to fix it would be great.

[Galant Evolution]

my guess would be to check the belts to make sure they are tensioned correctly and see if the squeek goes away..as for the rough idle, check plugs, wires, could be one of the pullys also.

[jlfisher360]

I had kind of the same problem but mine had a rough idle all the time and when the rpm was around 700, the idle was ok. My intake manifold was crack. Went to 4 different shops and they couldnt tell me what was wrong, so i had to take it to the dealership to find out.

[RayDub]

I Think my car is doing about the same. Maybe the belt just needs to be tightened. It just got cold here in AZ so when i use the heater things seem to shake a little more.

[ezekiel.glnt]

2003 Galant 4 Cyl. I changed my spark plugs and my car is idling rough when warm. When my car is still cold it idles fine, as it gets warmer to normal operating temperature the idling gets pretty bad. I feel the car shaking and some squeaky noise are coming from under the hood. After a while of driving (about 40 mins or so) the car idles fine with no squeaky noise. The RPM meter is at about 700. When I shift my car to neutral at stop lights, the whole problem goes away, no more rough idle and squeaky noises. Seems like when my RPM goes up by about 50 when my car is set on neutral, my car is fine. Wonder if I should adjust the idle rpm? Any help as what could be the problem and how to fix it would be great.

ruf idle can b numerous things,intake leak,dirty filter,fuel pump going bad,spark plugs not gapped rite,etc...its time to trouble shoot...i would get a can of carb cleaner and spray it around hoses c if idle changes,check gap on plugs,change fuel filter...

[01blackG]

Some time the rough idle is high millage after a while thats going to happen. Number one reason with high millage is normally the engine mounts are wearing or worn out pretty good. Doesnt mean they are blown out and bad, just worn and old. My car has the same vibration, it started on mine around 165,000 miles. Im not to concerned because i never replaced the mounts and im sure if i did everything would go away. As for the squeaks pretty sure its your belts. Also depending on how many miles you have on the car, make sure you fluids are up to date and cleaned / replace as the manual says. Also like some of the guys say above make sure your gaps on the plugs are correct and wires are good.