wwd_mbtch

I am fighting a rough idle on a 2004 SLK32. It is worse when first starting cold, and gets better as it warms up. I was wondering if this is a normal attribute of this engine. Will anyone with this car please respond so I can stop pulling my hair out. I can't find anything wrong with the car at this point and I think it's a normal condition. All input is appreciated. Thanks

430

No. I have no issues with my idle regardless of weather.

When you say the car has a rough idle do you mean it feels like the car is going to die? Or do you mean the car shakes?

If the car shakes check the motor mounts, they have probably gone bad.

How many miles are on the car?

wwd_mbtch

It only has 24k miles, The engine mounts are only a few months old. It has new plugs and wires. Can't find anything out of specs.

430

Does the car feel like it is going to die or does it just shake the whole car?

jerryxu

Sorry to hear that.
Mine has always been silky smooth, my 2002 is only 14500 miles. Her is what it does:
When it is just started (cold engine), the idle is high (like 1300-1500rpm), also a little loud (angry sounding)
within a short time (by the time I have the roof down) the engine is down to 500-600rpm and very smooth.
Put it in reverse, it is the same smoothness.

I would think you want to check all spark plugs. Make sure they are good and all firing. Then I would check the compression of all 6 cylinders. Problem with one of them usually causes shake due to imbalance. Hope you have it identified and resolved quickly! Let us know.

wwd_mbtch

thanks guys. It's a normal condition. If the car is cold and you start it let it run for a few minutes in park and then the idle will change and feels like car is misfiring, but it's not. Normal condition. Possibly running the engine slightly lean to reduce emissions. Compared to car with 9k on it, same.

jerryxu

Good to know it is ok.