[simzjr]

Hello,

About 3 months ago I changed the valve cover gasket on my 2011 BMW 328xi. Everything went well, but I did crack one of the oil seperators when it came out. I thought I would try to see if it would still run fine and sure enough it did. it ran fine for 3 months - until yesterday.

Two days, I had an oil leak and it was coming from the Valvetronic gasket. I removed the bolts and noticed that the plastic threads came out with the bolts. Therefore, I bought larger self tapping bolts and installed them (same length just bigger diameter). That stopped the oil leak and the car started and idled fine.

Yestrday, the problem started. The idle would surge from 1200 to almost 200 but I could drive it home fine from my place of work. It did set 2x codes and I recovered them using Carly:

002D06 - Air Mass System
002D15 - Air Flow Sensor, Measuring Range

Against what I already knew, I replaced the MAF Sensor and it did not make a difference. I unplugged the MAF Sensor and it did make a difference and I didn't have the surging idle. The oil cap comes off easy with minimal vacuum which to me says that there is not a major vacuum leak in the valve cover, right?

Here is what the live data is showing:

2 g/s MAF air flow (which is low, right?)
STFT sitting around +30 both banks (indicative a vacuum leak, right?)

All signs are pointing to a vacuum leak to me. Any other thoughts or any other tests that I can run to track / confirm? I am pretty frustrated at this point and I thought many heads are better than one.

Thanks in advance for all your help! While I am a new forum member, I have been using the forum for years to help me diagnose. This problem is a bit unique so I thought I'd register and see what other people may have to say.

Dustin

[E92William]

What do you mean by cracking the oil separator? You mean damaging the valve cover itself? Far as I'm concerned by 2011 that system was located inside the cover. Obviously first think I'd do is go over every connection of intake hose you have on the car and see they're all seated right, not uncommon after moving pcv hoses that they unseat after installation when driving the car hard. Any oil leaks on the valve cover from the eccentric shaft sensor? If this is bad enough it can actually pull air into the intake from outside of the engine. What do your short and long term fuel trims look like?

[HydroxFrost]

Sounds like you need an entire new valve cover assembly. The self tappers aren't an air tight seal. Its most likely that but it could also be your intake boot or another gasket causing the issue. You're right though, all signs do point to a vacuum leak of some sort.

[simzjr]

Hey,

Thanks for all the help guys! I wanted to follow up as I solved the problem and wanted to leave the answer for anyone else that is searching for a solution.

The problem was a vacuum leak and it was coming from the Valvetronic motor gasket. The self tappers were perfectly air tight but they distorted the gasket slightly (enough to allow unmetered air in). I removed the valvetronic motor and drilled the gasket holes slightly bigger to accept the self tappers then reinstalled and reseated the gasket. At this point the car fired right up and ran like new. These cars certainly are finicky on a tiny vacuum leak!

As for the oil seperator, yes the baffles are all integrated into the valve cover on the inside. When I was taking off the valve cover, as it was such a tight space I damaged one of the baffles. The good news is that after 10k km's, it hasn't had any effect on the engine or driveability.

Thanks again for taking the time!

Dustin

[E92William]

That's great glad you sorted it and posted the answer here. Seems every other person sorts out their issue and never says what it was