ML 320 misfire problems!
 

Hi,
I have a ML320 2000 with 165K miles. Code reader shows P0303, misfire in cylinder 3. After visiting a Mercedes Benz dealership, they told me I needed a new fuel pump, MAF, ignition coils and spark plugs with new wires! I declined the service because of the cost and the dealer's uncertainty that this would fix the problem.
I installed a new fuel pump (fuel lines were replaced @ 50K, spark plugs were replaced at 100K), all new spark plug wires, and 2 new plugs on cyl. 3 with a new ignition coil. It is still sputtering and eventually it chokes. I ordered an OEM MB MAF, coming in on Monday. If that doesn't solve the mystery, what is left to do?
Any advice will be considered and greatly appreciated.
Thanks in advance, John.

Sputtering ML
 

Possibly the injector is not working properly for that piston position? Otherwise, what you have replaced sounds very good basically and certainly won't hurt if you are keeping the car.

I suggest that you start with a basics..does that & all cylinders have correct compression.?

If so then swapping that coil & wires to a GOOD running cylinder would be a test of that part.

Even swapping spark plugs from that cylinder to another is a possibility..new parts can be defective.

Making sure that that cylinder doesn't have a vacuum leak..

Re-initialization of the crank sensor will rectify MANY running problems on the M112/113 engines on most 1998 & later cars.

A lean mixture can affect 1 cylinder ONLY if the that cylinder is already running lean or poorly..

My 98 ml320 got the same problems .
Code shows P0303, misfire in cylinder 3 also # 2 ,#1 .
Got all new spark plug and fuel pump but still run poor and Code shows up all 3 misfire (check engine light).:confused:

Please Help....

Thanks

So did either of you two cure your trucks ? ?
 

I sure would like to read some success stories.

steve

how is this done? thanks

Re-initialization of the crank sensor
 

Re-initialization of the crank sensor
Youre a Doctor- it would be nice to write that in laymens terms so poor red neck slobs like me understand it.

I replaced my crankshaft position sensor. Is that what re-initialzation is ?

steve

PS I am at the Mercedes Benz internet cafe---waiting for my new cats on my ML320. Hoping this will cure my poor idiling, missfireing, weak power at times and one stall. Yes I replaces my Mass air flow sensor last week. (and plugs after only 5,000 miles in a vein attempt to cure).

same problem missfire on 1,2 and 3 did you get sorted thanks
 

did you get your ml working if so wot was the fault in the end thanks
i have the same problem

Ml 320 2002 cylander 3 misfire
 

Hello. I have my engin light on and the code reads p303 misfire cylander 3. I replaced the coil and spark plugs and the the fuel injector, but, no luck.Any other advise?

Replacing the MAF cured my 2000 ML430 with similar symptoms.

Cheers,

Eddie

Yes, 99% of the time a "misfire" code means bad MAF sensor.

Think of it this way ... it misfired because it got a bad mixture, not necessarily because of poor spark.]

MAF sensors on these engines are notoriously unreliable and the ignition system isn't.

I went through 3 MAF sensors before my problem was fixed. eBay parts didn't work on our '99 ML320.