Originally Posted by BMWM.D.
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....
Great call, so the dealership did some work on the car and swapped the 4th injector to cylinder five and the code moved to the 5th cylinder. So they're gonna look over things with the remainder of the diagnostics time but it seems to be a slam dunk that it's the injector.
What is your recommendation in regard to changing just one of the injectors? So 4 options.
A.) Swap 1 with the same model injector as the other 5
B.) Swap 1 with the newest model injector from BMW
C.) Swap 3 on the same bank with the same model injectors
D.) Swap 3 on the same bank with the newest model injectors.
Thanks again for your help, it made it an easy phone call to handle from the dealership knowing what to expect. And for the $100 diagnostics fee it saves me the time that I don't have to troubleshoot.
Also, does this probably mean it was just a coincidence that the injector went after the valet drove it. It doesn't seem like excessive driving would lead to an injector issue?