N63 High-Pitch Noise. Need Help Diagnosing a Possible Vacuum Leak on My X5 50i

[KCG]

Hey guys, I need help diagnosing a possible vacuum leak on my 14 x5 50i with the N63TU engine.


The noise seems to be emitting around the hot vees, especially around the turbo areas. Please see video here

Besides the high-pitch noise, the car sputters intermittently during higher speed acceleration above 60mph+. It feels like the car lags and is losing power.

I ran OBD diagnostics multiple times with no fault codes. I have replaced the air filters, all eight spark plugs, and ignition coils, but it did not fix the sputtering issue.

I also checked the MAF sensors, PCV lines and valves, turbo inlet seals, and charge pipe seals, and everything looks fine.

Upon further inspection, I noticed one of the vacuum lines looked very new and had been replaced, and it has a rubber cap plugged into it. Most likely, the previous Indy shop I went to messed something up when changing the turbo intake ducts and had replaced the vacuum line without me knowing.

Replaced Vacuum Line, #6 in Diagram, Part: 11657645222

Rubber Cap Part: 11667803829

X5 F15 X5 50iX Vacum control-engine-turbo charger Diagram [Link]


The Rubber cap that was found in the E70 50i [Link]



However, looking at RealOEM.com and multiple BMW part stores, this rubber cap doesn't seem to be used on the F15 N63TU engine. It was only used on the F15 N57 turbo diesel and the previous e70 and other first-generation N63 series.

I proceeded to do a little test and unplugged the rubber cap. Lo and behold, the high-pitch noise completely disappeared. However, unplugging the rubber cap caused the exhaust note to sound much louder. Also, the car runs choppily, and the sputters under high-speed acceleration have worsened.

As soon as I plugged the rubber cap back on, the high-pitch noise came back. So it seems like it is a vacuum leak issue. But I'm confused, is there supposed to be a rubber cap plugged into this vacuum line? Because it is not presented as a part used for the F15 50i. If not, where does this connector go to?

If there is supposed to be a rubber cap, could this be a possible vacuum leak near the vacuum tank? Possibly near the T-connector (#16 in the diagram) or a line that is not attached correctly?

Any help would be greatly appreciated. Thank you!

[Mhutchman]

Did you ever solve this?