Missfiring except with Premium - PeachParts Mercedes-Benz Forum

paul roberts · #6 11-19-2023, 04:01 PM

Quote:

Originally Posted by tivoliman

Yes - I finally got to doing this test. Switched the coil packs between #5 and #7.

Magic - the CEL reported that the misfires (from P0307 to P0305) moved from #7 to #5.

I think we have the root cause.

Thanks so much for your patience.

Comment: I have changed the spark plugs and the wires, but missed changing the coil packs.

So - replacing the coil packs now is fair.

Suggestion to All Reading this. Changing the coil packs when you change the plugs (I was penny wise pound foolish)

This is a M113.940 engine, Model: E430 Year: 2002

I never understand the logic of running regular in the m113 engine and other modern engines that call for premium. Of course your car runs fine on regular. You have knock sensors that adjust the timing, but your fuel economy goes down during the process.......and there goes the few bucks that you saved at the pump.