2010 328i Lean Condition?

Repair order information - customer states that car overheats when driving, has cel on, and there is an oil leak. All of this popped up after an oil change.

Oil leak is coming from the filter housing. A lot. Guessing it's the gasket for the cap, maybe wasn't replaced. I did notice it's an aftermarket dorman part. Oil was pooling everywhere around it and on the serpentine belt. Customer said he just had that belt replaced too. Oil level is ok.

Global codes are ho2s heater control circuit b2s2, random cyl misfire, cyl 5 misfire, cyl 4 misfire, mass or volume air flow a circuit range/performance - air flow too low, system too lean bank 1 and 2.

Enhanced codes add a cylinder 3 and 6 misfire, and electric cooling pump - missing, and electric cooling pump -power reduced operation, power management battery.

The battery voltage pid said 13.6v. car runs poorly when first started, definitely misfiring. I couldn't find any vacuum leaks using propane and watching stft. Have not smoked it yet. Maf is low at idle reading about 1.6g/s.

The weird part. I was watching the fuel trims and they were in the 30s on both banks, total trims. Adding throttle brought them down, which is why I was looking for a vacuum leak. I though I hit the Lea because stft dropped way down to like -20 on both banks, but then went back up. I heard something cycling with it did this back and forth a few times. I took a break and went back out later thinking it might have been the AC compressor cycling so I started the car with the AC off, got it up to temp, stft deep in the negatives. When I turn the AC on, they jump up again. I turned off the AC and this continued to happen. Here is a shot of some data.


They aren't going to let me play with this much longer before it goes to BMW.

Not sure what to make of that. Thoughts?




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My plan is to test the battery in the morning and tonight check a diagram for the MAF, maybe find a good wave pattern. I moved away from MAF earlier because of the trims getting better with rpm but the low idle readings have me wondering.

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I m just thinging,
hmmm ...
I would take a look at the loop status ...
Is it staying Close loop all time or switching to Open ??? .. . hmmm ...

BMW are very famous for internal vacuum leaks also ...

If smoke doesn't show up ... check if there is any vacuum at the oil - dipstick / brake booster etc ...

Ofc maybe i am completely wrong in my thinking ...

No, those are good thoughts. Thanks. Unfortunately it sounds like I am just going to be cleaning up the oil and shipping it out today. We are a Nissan dealership, so any off brand cars don't stay here long...

I'm with Andreas81, crankcase vacuum would be high on my list to check.

That filter housing is almost certainly puking out. :silly: It's kind of a mother to replace... How much does this guy love his BMW? Because between that, the CEL and the water pump, he's gonna be hurting.

From the condition of the inside and outside of the car, he doesn't love it much. The thing is a roach.

I'm pretty sure the BMW pcv thing is under the intake on these too. I remember doing one on a 3.0 a couple years ago.

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I'm struggling with this PCV concept a bit. It relieves pressure from the crankcase. If the valve gets clogged, it can force oil out of seals or pop the dipstick.

What should happen if you pull a dipstick out or take off an oil cap, or would there be two different results there?

This car does not have a dip stick- FIY.

Shouldn't be any different results. You can pull the cap and put your hand over the opening. If it sucks your hand in, bingo. If not, continue your search.

Hearing the crank/cam seals sucking air would be another clue. Sounds like a hooting or squealing noise.