I recntly bought '90 300SEL with 77000 Kilometers (app. 49000mi) on it. All records and in pristine cond. After warm up sometimes it will idle rough. I am going to change wires cap & rotor, but wonder if this model might have a common problem that would save me alot of searching and worry. The car other than that works flawlessly in every other respect which leads me to believe it is not something serious. I also burn Sunoco 94 octane fuel, expensive but MB deserves it. One other thing, An absolutly fantastic web site! Nice going you guys.

Chris,
Since sometimes the car idles OK, I think you are on the right track. Ignition system componets can cause rough idle problems. How about the spark plugs & compression, make sure to gap the plugs at .040".

I have seen the mid-grade fuel acutally run better in this engine than the high-grade.

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Benzmac:
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