Hi all,

Looking for any help with possible causes. My wife's C230 Sport was running just fine till 2 days ago when it started to run rough in the middle of an 80 mi. jaunt, like it was skipping a cylinder, but intermittently, not in a consistent way like if it had a bad coil on one cylinder. The missing is occassionally accompanied by what sounds like a muffled backfire into the airbox (don't know if that's even possible w/modern engines) and also occassionally what sounds like a muted mechanical "clunk". Not positive whether it's from inside the engine or possibly outside from the engine reacting to the miss. The thing is, there's no Check Engine Light that would indicate that the ECM is aware of the fault.

I would appreciate any suggestions on troubleshoooting this problem.

Thanks in advance.

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Gary

1992 300E, 2006 E350 and 2006 C230 Sport