[Meatos]

Originally Posted by mweisdorfer

Both the Rob Beck PCV valve & Mishimoto catch can perform as advertised....

Sounds good, just installed Mishimoto OCC after cleaning the valves, have the rb pcv since earlier

[Bimmer_Engineer]

What are the symptoms of a bad/failing pcv?

[allcaps55]

Is this still effective without tapping and plugging the head? I just recently had the VCG replaced and don't exactly want to take it apart again right now.

[unrealii]

...with understanding everything Rob said above with the cyclonic oil separators, I don't understand the logic that a baffled OCC can out perform the oem setup.

[sparkyblue]

Originally Posted by feuer

They are two of them. One is build in into the valve cover and isn't serviceable or replaceable. Oil cap leak and leaking valve cover gasket or cracked valve cover are the usual cause for slow boost build and boost leaks on the n54. I don't suspect the PCV valve to be the reason at moderate boost levels.

Can someone explain technically why a badly sealed valve cover gasket and/or a cracked valve cover would cause slow boost build?

I believe this is what’s been causing our slow boost issues all along. I’ve done the valve cover gasket, but still notice some oil around cyl 3 & 4. Leading me to think it’s a cracked valve cover.

Ive eliminated boost solenoids, turbos, wastegates, boost leaks and carbon build up as possible causes. The car doesn’t go into limp mode, but I notice a half a second delay in throttle response as compared to my N54 135i’s spool up throttle response.

The only thing left is the PCV valve, which is currently stock. I just ordered an rb pcv valce and will see if that helps the slow boost build.

Side note, I see lots of oil build up around the oil fill cap, and smell burning oil when I park the car in the garage.

[arkie6]

The valve cover has channels that connect six ports in each of the six intake tracts in the head and all six channels come together at the internal PCV valve. If your PCV valve, which is normally under vacuum under low load, is leaking when pressurized in reverse (during boost), this can be pressurizing your crankcase. Pressurizing the crankcase can cause oil to leak from seals, compromised gaskets, and oil fill caps that don't seal tightly. The initial pressurizing of the crankcase could possible be felt as a throttle lag as this is a large volume to pressurize and it would take some time to come up to boost pressure.

The best way to eliminate this is to plug the ports in the intake tract with setscrews and lock-tite which completely eliminates any chance of pressurizing the valve cover and crankcase. This would eliminate the vacuum side PCV unless you go with an external vacuum side PCV setup.