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engine misfire at high rpm and load

3K views 4 replies 3 participants last post by  brian/ont 
#1 ·
My 2000 ML320 with 89,000 kms misfires at high rpms in combination with heavy throttle/loads. For example, cruising at 120kph it's ok, but if I step on it to pass, the engine misfires until I let up on the throttle. It feels similar to a bad spark plug, ok normally, but fails under heavy loads.

I had it to the dealer back in Novemeber, they replaced the MAF sensor while still under warrenty, but found no codes. This improved the problem, but it was still there. They also checked for a plugged exhaust/catalitic. I wanted them to change the plugs at the time, but they said they felt it was not the problem.

Now that I'm out of warrenty, I don't want to be paying for their experiments in resolving the problem.

Has any one experienced something similar, and what did you do to repair the problem.

thanks...........brian
 
#3 ·
Good thought, but at 120 kph (75 mph) that can't be it!

If he is cruising at 75 mph and takes the pedal to the metal, the trans should downshift to the appropriate gear and take off. Presumably, it would not downshift to the first available gear that results in slightly below 6000 engine revolutions per minute.
 
#4 ·
Brian, since you reported the problem BEFORE the warranty had expired

and since the problem was NOT resolved, I think that the problem is still covered by the manufacturer's warranty.

Do not despair, I don't think that you'd have to fight much to have that covered. Someone like Drew can probably counsel you better on what course of action to take if the dealership disagrees with this point...
 
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