[USVIJIM]

I just started flash tuning my M235i with the N55 (MHD). After getting to stage two I noticed a squeal/whine when pushing hard through low gears. Thought maybe a boost leak or something but no codes at all and my logs submitted to MHD are perfect. The location of the PCV made me suspicious that could be the issue. Saw a couple videos with the exact sound but I am not getting the constant squeal.
Had a video (Fritz Ramos, YouTube) show up on my feed testing the PCV valve on an N55. The test is hooking up a vacuum tester (MityVac) to that nipple on the PCV valve when the car is off. Pump vacuum to 15 PSI and it should suck the bladder and hold there, mine will not. Saw a couple other videos so leads me to further suspect this is the issue. Read threads on Bimmerpost describing the issue and fixes, the rubber bladder in the PCV can tear. PCV is integrated into the valve cover but I have also seen fixes that I will attempt first.

I don't want to replace the VC because I have that unicorn Bimmer that isn't currently leaking at 60k miles. I ordered a Vaico cap from FCPEuro (they also make a valve cover) and another from Amazon that looks more similar to OEM but it's for the S55, may return it.

Take a look and let me know if you think I'm on the right track.

[XutvJet]

Boost leak. Can't say I've ever heard of the PCV failing on a 2014+ EWG N55.

[USVIJIM]

I've seen plenty of posts about them failing. My boost target vs actual seems to be fine and MHD said logs were good. I'll check connections. I've only found two videos of checking the PCV with a vacuum tester.

[USVIJIM]

https://youtube.com/shorts/N3_TvGiaupU?feature=share