1987 300E

Don't drive the car all that much but the last couple of weeks I've been having an issue. Upon a cold start the car runs fine, normal, idle smooth, acceleration good, etc.

Just before it the temp gauge shows fully warmed up coolant (just below 80C on the gauge) one of two things happens. If I'm just cruising along the engine with stutter for a few seconds (lose RPM and act like it's running rough), then corrects itself (maybe repeating a time or two) and run fine the rest of the trip. If I have to stop at an intersection right as it hits this point all will appear and feel right...until I go to move again. Then I get a major stumble from the engine, to the point of the engine shutting off about half the time. It restarts with a bit of cranking (more than a usual start up though). This may repeat at the next light (30-50 seconds away) but then it runs well till the next full cold start.

I'm thinking it has to be related to a coolant temp sensor failing but am open to other thoughts. Ideas?

Thanks for your input!

Experienced the same problem with a 1991 300CE (104 engine) and a new Oxygen sensor resolved the problem.

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Fred Hoelzle

I would hope that isn't my problem as the O2 sensor is less that 15K miles old, though I will test it to be sure.

Any other ideas?