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Discussion Starter · #1 ·
Posted the other day that I could alternately start and drive my ML - it would run great - and then stop, restart, then 'Service Engine' light would come on accompanied with a 'rough running' engine. Could then stop and restart - light off, and run great again?! Been doing this for about 3-4 days now.

The initial reply from the board was to go and get a diagnostic printout at my local AutoZone (great tip) and get back with the codes. Well here they are (and there are 2 codes with a message):

P0300 - 'The PCM has determined that multiple misfires have occurred'

P0302 - 'The PCM has determined that a misfire has occurred in Cylinder #2

Probable causes:
1) Spark plugs ignition wires (had these replaced about 12k ago)
2) Vacuum leak (?)
3) Injector fault (fuel, octane/cleaner?)
4) High or low fuel pressure (?)

Well - I took my car and readouts to my 'secondary' service man (needed oil change) and he checked the plugs and said they were in fine condition (12k miles since changing) and thought the problem to be a coil. How much is a coil?

I would appreciate any input on this problem and would appreciate any thoughts. Or at this point, should I just take to my regular service center? TThanks in advance!

ReBell
 

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C9H9N Offensive Odor Exuder
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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There is not just 'a' coil. There are several (one for every 2 cylinders, I think). 43sqd would be able to give you a clearer picture.
 

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Discussion Starter · #3 ·
followup to my post above.....

I have since checked my service records and discovered that the plugs and wires were replaced 16k/8 months ago. Beginning to sound like the coils - I hope!

ReBell
 

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Outstanding Contributor
2006 ML500 2002 ML320
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The easiest way to find out if you have a faulty coil is to swap #2 coil with a coil on the oposite bank, e.g. #5 Then clear the codes and drive the vehicle and when the CEL comes on again have the codes read again. Of course if the misfire is now on cyl. #6 you have found your problem. If it remains on cyl. #2 then it is an injector problem, providing that you have already spoken for the plugs and wires.

The price for a coil at the dealer is approx $182.
 

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00 ML 430
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43sqd gave the purrrfect advice. Confirm which coil pack it is and go from there... I found one for $137 for your car at autopartswarehouse (dot)com
 

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Discussion Starter · #6 ·
Thanks guys for advice....

is it one coil I need to order or two? I am going to try recs above and go from there. Anyone have a P/N?

ReBell in MS
 

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1999 MTrash 430, its a joke
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Your 430 has 8 coils, not cheap to guess which is at fault. As previously recommend swap a coil from any cylinder and the #2 coil. Erase codes and drive it. If it switches to the cylinder you swapped coils with, there is your affected coil. If it doesn't, then it either plugs, plug wires, injectors or something else directly affecting that cylinder.
 

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2006 ML500 2002 ML320
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is it one coil I need to order or two? I am going to try recs above and go from there. Anyone have a P/N?

ReBell in MS
If, and I repeat if, the coil is found to be faulty, you would only have to order one. Each cylinder has two spark plugs & wires, one for intake and one for exhaust, which are fired by one coil. But in actuality that coil is composed of two individual coils housed to appear like one.

The OE part # is 000 158 78 03.
 
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