Z4 M54 Engine Whining - Driving Me Nuts!

[cmybimmer]

I was driving my dads Z4 for a couple of days, and while driving a slight incline on the freeway i was trying to speed up and get in front of a car to make my exit. I floored it and the car kinda hesitated/sputtered for a sec, but eventually made it. After i got in front of the car, although no more hesitation, i start hearing a whining sound from the engine. Luckily i was close to home, so i drove it home trying to diag it under different conditions (low rpm, fast rpm, different gears etc). It is apparent through all the gears, and rpm dependent. While at a standstill and foot on brakes, i hear a difference between changing the gears. The transmission shifts perfectly fine.

So i did/changed the following to no avail:
Transmission fluid & filter change
Using known good parts from my e39 with same engine, i replaced the ICV and the DISA valve and it did nothing.
Removed the serpentine belts to rule out bad pulley/belt/alternator and bearings, and whining was still there after removing the belts.
Pulled the engine oil cap while engine was running to test CCV, but suction was satisfactory.

The only suspicions i have left are either the CCV crapped out, or something fuel related like the purge valve. But im tired of just guessing and i decided to resort to my forum brethren to see if anyone else either experienced this or know where to look next.

See youtube vid for sound clip of whine:

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

Thanks!!

[Steeler]

Vacuum leak possibly.
Check the hose to the TB and ICV, they decompose pretty good.

Items 3 and/or 5

[JAS1169]

I was going to call it as a bad pulley within the serpentine belts system but, you already ruled this out. Given that, I'd agreed with focusing on your vac system.

[garz747]

Have you ruled out the power steering pump or is electric on that model/year?

[cmybimmer]

I'll check for vacuum leaks, thanks!

and, I'll have to check the power steering pump. IIRC it had the traditional power steering pump, and that shouldve been ruled out by taking off the accessory belts. Not sure if it is the electric system

Thanks for the replies!

[Lucky1]

Originally Posted by cmybimmer

I'll check for vacuum leaks, thanks!

and, I'll have to check the power steering pump. IIRC it had the traditional power steering pump, and that shouldve been ruled out by taking off the accessory belts. Not sure if it is the electric system

Thanks for the replies!

Subbed. I have a similar whine on my 128i that is rpm dependent. May not be from the same cause as this but interested in the education nonetheless. In my case the whine is only present when the a/c is running as determined by increasing the rpms so the whine is very high pitched then turning the a/c off. Sound goes away immediately.