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.

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2003 AMG S55
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