Rough running 2006 E350 M272 Engine
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2006 E350
Rough running 2006 E350 M272 Engine
Hi all, I am new to the Mercedes world but am pretty mechanical myself. I just bought a 2006 E350 with the M272 V6 engine. I have an issue that I am trying to investigate and I am trying to look into the problem in an efficient manner.
I bought the car not running and quickly found that it was a burnt out fuel pump fuse. When I got it running, it now runs extremely rough. I pulled the codes:
P0300 - random misfires
P0304 - cylinder 4 misfire
P0305 - cylinder 5 misfire
P0306 - cylinder 6 misfire
It basically seems to be running on only 3 of the 6 cylinders, this thing runs ROUGH. I originally suspected O2 sensors, but I swapped the pre-cat sensors and I still had issues on the same side of the engine (bank 2). I don't think it is coils or plugs or wires because they were replaced AND I swapped them from the effected cylinders to the others and still had the issue. Finally, I had a shop look at it and they said the catalytic converter was fine, as I suspected it might be blocked. They then told me that they believe it is a timing issue.
Did some research and it sounds like these M272 engines are prone to a balance shaft issue as well as camshaft solenoid failures. I hope to god that the balance shaft isn't the issue. Reading up on these issues though, it seems that there tend to be codes thrown for these issues. I also don't believe that a faulty balance shaft would cause misfires on just one side of the engine. Do you guys have any advice as to what I can look at next? Thank you for all of the help!
I bought the car not running and quickly found that it was a burnt out fuel pump fuse. When I got it running, it now runs extremely rough. I pulled the codes:
P0300 - random misfires
P0304 - cylinder 4 misfire
P0305 - cylinder 5 misfire
P0306 - cylinder 6 misfire
It basically seems to be running on only 3 of the 6 cylinders, this thing runs ROUGH. I originally suspected O2 sensors, but I swapped the pre-cat sensors and I still had issues on the same side of the engine (bank 2). I don't think it is coils or plugs or wires because they were replaced AND I swapped them from the effected cylinders to the others and still had the issue. Finally, I had a shop look at it and they said the catalytic converter was fine, as I suspected it might be blocked. They then told me that they believe it is a timing issue.
Did some research and it sounds like these M272 engines are prone to a balance shaft issue as well as camshaft solenoid failures. I hope to god that the balance shaft isn't the issue. Reading up on these issues though, it seems that there tend to be codes thrown for these issues. I also don't believe that a faulty balance shaft would cause misfires on just one side of the engine. Do you guys have any advice as to what I can look at next? Thank you for all of the help!
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2006 E350
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i just did some more digging since I picked it up from mechanic. He said it was bad timing but I just checked the timing stamps on the cams by rotating the engine manually and they lined up perfectly center in the hole so I suspect the balance shaft and timing chain are ok. Any other ideas?
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2006 E350
Thanks! So I just got my hands on a compression test kit which is usually what I check first but didn't have it available. Low and behold, cylinder 6 (which is always the first cylinder to throw a code before the rest) reading at dead zero compression, all the others are healthy at 150psi...
Looks like I am going to have to do some serious work. Not sure how complex of a repair this might be. Any points of investigation please let me know. Thinking maybe a bad valve spring or something.
Looks like I am going to have to do some serious work. Not sure how complex of a repair this might be. Any points of investigation please let me know. Thinking maybe a bad valve spring or something.
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