W210 Rough Idle
 

Hi, Folks,

I have a 2002 E320 with 68,000 miles on the clock. Last year, I began to notice a roughness or miss while idling on rainy days. The shop checked it over and couldn't find a reason for the condition. The problem just went away once the weather cooled off last fall.

Well, now it's back. Does anyone have a suggestion as to how to address this problem? There are no fault codes showing on my meter. Should I be concerned, or should I just consider this to be an idiosyncracy of this particular vehicle?

Thanks for your help.

I replace lots of ignition wires on M112/113 powered MB's with over 40,000 miles. The good news is that they run like new afterward. The bad news is that the wires aren't cheap.

my guess is your MAF might be on its way out. try cleaning it or replace it next time u get new air filters

Rainy weather could be
 

causing an arc from a plug wire to a ground. When air is moist, it becomes more of a conductor. Put car in a dark garage and run engine while idling roughly. Look for arcing off of plug wire.

Followup......
 

Hi, Folks,

the rough idle turned out to be a miss on the #6 cylinder. My Indi, World Foreign Car in Richmond VA, replaced both spark plug wires and everything is fine.

Thanks for your help.

Steve