Debugging serious engine miss - W124 400E - PeachParts Mercedes-Benz Forum

czwbkx · #1 12-23-2007, 09:35 PM

My 400E starts and runs perfectly - for 2 minutes, 53 seconds. Then it starts to miss horribly - sometimes even goes into guardian mode. The timing is repeatable. The engine is not yet up to temp, but the transition is sudden and unmistakable - it's as if someone threw a misfire switch. Does anyone know the ECM program well enough to tell me what might be happening at three minutes into run time? Is there a certain sensor being checked, or a specific algorithm starting up?

I've already changed the spark plugs and the fuel injector wiring harness.

ILUVMILS · #2 12-24-2007, 05:56 AM

Did you check the distributor caps and rotors?

czwbkx · #3 12-24-2007, 08:36 AM

Hmmm. Not yet. Is a visual inspection good enough to confirm it as a possible cause, or should I just order new parts and install them?

david s poole · #4 12-24-2007, 09:38 AM

those dist caps and rotors suffer from the infamous green crud,need to be replaced, common problem.

czwbkx · #5 12-24-2007, 10:04 AM

OK - I ordered 'em. Thanks for the tip. I'll post results here.

Anything else "while I'm in there?"

czwbkx · #6 12-29-2007, 04:36 PM

New caps and rotors fixed it. Between the upper harness, plugs, caps, rotors - I should be in good shape for a while, eh?

ps2cho · #7 12-29-2007, 08:22 PM

I've been trying to route down my misfire for quite some time. Glad to hear you got yours fixed!