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      03-31-2013, 01:03 PM   #15
Stupid Idiot
BMWM.D.'s Avatar

Drives: E90 335i & C6 Grand Sport
Join Date: May 2009
Location: Santa Barbara

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Originally Posted by pits200 View Post
Thanks bmwm.d, I know from your posts you're extremely knowledgeable. I was getting a misfire on cylinder 4 multiple times it was only that cylinder. I had the car towed to the dealership and at minimum I'll pay the diagnostic fee and hopefully that will narrow down the issue.

What about the squeal at first? And is there any possibility of 02 sensor? I thought the 09s and laters had the updated injectors and less prone to issues.

I rarely see 02 sensor issues on these cars. Doesn't mean one can't go bad, but my bet is on something else. If the exhaust smells like raw fuel, it's sure to be an injector issue.

I'm not exactly sure what that noise was when it first started -- but it could be something to do with the fuel system that's related to the root cause of your problem (injector, high-pressure fuel pump, etc.). I'd be chasing the performance/driveability issue first, and wouldn't be too concerned with the noise for now.

Just keep in mind, IF it is a leaking injector (and raw fuel is entering the exhaust system), you can have a bunch of secondary faults that can throw you. A while back I repaired a car with a leaking injector, and for quite a while afterwards I was still getting oxygen sensor and fuel trim faults from the residual fuel in the exhaust. The good news is you don't seem to be driving the car around like an idiot, so that's good. The last one I had actually melted a primary cat from extended driving with the injector failure.

I think I've posted this before, but most of the badly leaking injectors I see these days are on '09+ cars. I'm not sure why.... but the older style injectors don't seem to do this. Sure, they cause rough running on cold-start and misfires, but I don't think I ever saw an '07-08 car fail like that.

Good luck getting it taken care of....