97 e320 rough idle
 

97 e320 has 96,000 miles on it. When I bought it a month ago, the check engine light was on. Took it in, and the mechanic changed the spark plugs. The check engine light was not on anymore, however, it idles rough. After I drive it for awhile, the idling (say, if I am stopped at a stop light) is a little better, but the idle speed does not stay constant. When I first start the car, the rangeof the idle speed is a little more. </P>


Any ideas on what could be the problem? Oxygen sensor? Dirty fuel system/injectors? </P>


Thanks a lot y'all</P>

97 e320 rough idle
 

Jon, I also recentlypurchase a 1997 E320 with the same exact problem. If you have discovered cause please let me know!</P>


Thanks,</P>


Morrissey</P>

RE: 97 e320 rough idle
 

I too had the same problem with my 97 e320. As described my check engine came on due to bad spark plugs which was changed. Thereafter the car would vibrate a various speeds. After exploring various possibilities I suspected that the computer began compensating for the misfiring cylinder but never stopped even after the plugs was changed and the check engine light went off. Due to this suspicion I connected my code reader which showed various error codes and decided to reset the system to clear the codes and to my greatest pleasure the vibrations stopped and power restored. Hope this helps.

RE: 97 e320 rough idle
 

Change the plug connectors under each coil.
There are three and are a comon cause of 104 misfire faults.
F8DC4 Bosch is the new replacement. [ No plats]