My 300 CE just developed this miss / erratic idle. After making sure I just did'nt get some bad gas etc. I'm getting ready to take a look at it and wanted some opinions:

Idle (around 600 or so) has a very steady miss / shake. When you start out, I get a sputter, then it smooths out and runs fine (Better than fine actually) I did a tune up about 2 months back so it has Cap, rotor, wires and plugs. (all OEM stuff - not aftermarket parts)

If you raise the idle (with the gas pedal) to 800 rpm or more, the miss is gone. On the highway, the car runs like a million dollars with no problems at all.

It seems like a CPS problem but since I'm not too familiar with the MB, I wanted to get some input. I have the service manuals here with me. ANyone had the same problem? I drove the car appx 35 miles, stopped for a family get together (about 4 hours) and it started doing this immediately after starting it for the ride home.

Thanks for the input

Brian

Dear Bryan, my car has the exact same issue...have you figured it out yet? If so could you send me an email with the fix at [email protected]
Thanks a million.
Antonino

CPS?? Crank position sensor? That would sure be a wild guess on my part since it exhibits no symptoms of a crank sensor.

My first crystall ball guess would have been spark plug connectors, but you put new ones on. Second guess - vacuum leak.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician