Hi guys I have a 2000 Mercedes C230 Kompressor with 118k miles on it.
Over the last month or so the car has been displaying the following symptoms:
[ul][*]Starts fine, idles fine when cold.[*]When warm engine idles very rough, at high RPMs there's a heavy shake of the entire engine.[*]At rough idle I shut the car off and restart and rough idle goes away until put under a load again (after a few minutes).[*]Very rough transmission shifting occurs.[/ul]Does anyone know what might be causing this or a possible solution?

I read somewhere about similar symptoms being caused by improperly gapped spark plugs so I just changed out my plugs today to the Manufacturers exact specifications in the owners manual. I haven't tested the car yet so I don't know if it made a difference in the rough idle. The car is still shaking at high RPM's though with the new plugs in. I also read it might be a bad MAS but I wanted to check with the gurus here for any advice before I spent the cash on parts.

Any input or help would be much appreciated, thank you for taking time to read this!

 

MB190e 1985 has similar symptoms after adjusting its RPMs. But it is nothing to do with spark plugs- its got Bosh Platimum 4+ and newset of wires. Can it be Fuel Pump Relay/catalytic converter/fuel filter maybe/bad fuel?

 

rough idle or shake can be from bad spark plugs or plug or even a bad plug wire so the motor is mis-firing. It can also be the timing is off for some strange reason or gas issues.

 

I would check the wiresand the MAF.