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M272 ML350 random Misfire

27K views 12 replies 9 participants last post by  martin h 
#1 ·
My 2006 ML350 randomly starts misfiring and running rough and turning on the engine warning lamp. Once restarted symtoms disapear.The diagnostics pointed to random misfire cylinder 3 & 4. All plugs were replaced, and coils 3 & 4 were replaced. The problem has reapeared... Dont feel like replacing more parts unless I am sure it will solve this issue. Any ideas?:confused:
 
#4 ·
Funny this should pop up today. Yesterday I was driving my 2006 ML, and merged into a lane with one car coming my way. I pulled out ahead of him, and had misjudged his speed, so i stepped into the gas pedal to get some distance between us. 6500 rpms. My check eng light started blinking and when I came to the stop light, my engine was running like crap. Ran that way for 50 miles. Got to work, downloaded the codes, and it was #1 cylinder misfire. Started it again later that day, ran like it was new. Took it out for a test run...acellerated to about 95mph and it ran like a top. I have 94k on the plugs, so they are due for a change, but I suspect this was induced by my romping on the gas ( although that should not be a problem for this machine).
 
#5 ·
I understand that with basic code readers it will tell you the cylinder that is misfiring.
However they do not tell you why in most cases.

If you get different cylinders move the coil pack to another cylinder and see if it follows to that cylinder. If it does not then looking into things like MAF sensor, plugged cats, spark plugs, vacuum leak, EGR, O2 sensors and the list goes on.
This is where a scanner that can give you real time data as you are driving to read sensor values is needed.
 
#6 ·
Having the same issue.
It went to the shop, had lots of stuff done, including plugs.
It's very random, and clears itself.

My C never cleared itself like this..weird.
Anyone have any advise?
Is this the beginning of the dreaded balance shaft issue?
Very close to 100K miles....
 
#7 ·
Must be something going on. Yesterday I was driving and the check engine light started blinking , then came on steady . Car seemed to run just fine for next 5 miles , then I noticed a misfire and lack of power. Drove for another 5 miles and turned engine off. Restarted engine and everything was just fine. Car ran good for the rest of the day. I also notice the fuel economy was worse then normal.
 
#13 ·
Engine ECU gets to hot...

Mine has the exact same problem, i tried evreything, but if i drive without the airfilter which divert a lot of the heat from the engine, then the problem dissapperes, and if it's really bad and i cant get it to run on all cylinders, i disconnect the engine ECU, unclip it and put it in my freezer for a few hours, and when i attach it again, the engine runs like a dream...
Ive tried everything, for months now, i sending my ECU to a company in germany who checks and repair the ECU if it's faulty..
Sometimes i can even just slap really hard at the top of the ECU and it suddenly runs like a Mercedes again, that is until next time i stop it, and tries to start it again...
 
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