N20 Engine 40e Turbo Squeal during Acceleration (Upgraded Turbo)

[EverTemple]

Hi, this is my first post, so if I did anything wrong please correct me.

I own a 2018 x5 xDrive 40e with a bunch of upgrades, some of which are an upgraded turbo TTE400 from TTE (TheTurboEngineer) and FMIC from Wagnertuning.

I have come across an issue with the turbo since the day of installation. During acceleration at low rpm (2-3k), following the turbo spooling is some sort of squealing sound that I suppose is from the turbo in high pitch.

I have contacted TTE regarding this, which they have replied that it is an abnormal sound and advised me to check for shaft play and leak. However, when I checked for shaft play, it is minimal (normal range), and no scratching of the turbine against the wall.

No leak was identified from the system yet, but the test couldn't be performed properly. The smokes from the smoke test machine went in but got diverted out (Smoke injected into FMIC turbo inlet port, goes into charge pipe, diverted out into a vacuum pipe under the charge pipe that routes back to the turbo inlet, then proceeds to leak back out from the turbo inlet vacuum to the air filter box direction rather going into the system.) I am not sure whether this is an expected behavior, and a few of my technician friends including the installer are also unsure.

So here I am, stuck with the sound, unable to proceed with the smoke test and no idea what is causing the sound.

I am hoping someone from the forum will have insights as to what might the sound and problem be.

You can take a listen to the recording of the sound on Google Drive:
https://drive.google.com/file/d/1Hi3...bytnA2svf/view

I also included the audio recording in the attachment in case the file gets removed from Google in the future, so everyone can still listen rather than broken links.

Thanks in advance

[c00lbeans]

the first high pitch whistle sounds normal. my wrx with intake sounds like that. the second lower tone whine in the background that sounds like tires in a parking garage does not sound normal if that came from your car and is not background noise. sound like belt squeel or bearings.

[EverTemple]

Originally Posted by c00lbeans

the first high pitch whistle sounds normal. my wrx with intake sounds like that. the second lower tone whine in the background that sounds like tires in a parking garage does not sound normal if that came from your car and is not background noise. sound like belt squeel or bearings.

Funny enough my friend did thought it was tyre spinning when he heard the sound. But I told him otherwise.

I am not sure if it is the timing because I tried to rev it during neutral and it doesn't produce that sound, neither if you drive fast at high rpm. It only happens during low speed low rpm in Drive while attempting to accelerate (will not produce the sound if coasting either). As for rod bearing, can't seem to find any symptoms such as abnormal oil level or knocking sound yet.

Anyhow, I will try to take a look again soon for the timing belt, as for bearing, might be more difficult to diagnose.

Thanks :cheers: