Engine knocking sound

Hi everybody,

I know I am in the S6 section, but it does get more attention.
As some of you may know, I became the owner of a V10 by buying an S8 in june 2021.
Not so long ago it started making an horrible sort of whistling noise, a bit like a bad bearing. Since I was very close to my destination, I drove it a few more kilometers, really slow and easy on the gaz pedal.
The same day, after the engine had cooled off, I started the car again and the noise was completely gone… but remplaced by a knocking sound. I tried to get some footage but my phone seems to be more interested in the normal ticking of the high pressure fuel pumps than anything else. Though, I did find someone that had captured a sound very similar to the one I’m (sadly) hearing. Here’s the clip :

For info : I opened the intake manifold last week and found 3 change over flaps still in place, but completely loose. Had to break one that was very wild and willing to fall, the other 9 are secured in the long runner position. Now that i started the car, when slightly pressing the gas pedal, it makes the knocking sound (subtle because I did not rev it hard, of course…) and seems to be gasping for air.

What are your thoughts ?

Thank you in advance,
Max

Do you have a check engine light on? Any codes? Is the intake Y plenum the throttle body’s attached to, okay?

Hi Revolv0,

No CEL bur several errors on the dash : parking brake, ESP, that’s because the car car has been sitting for almost 2 months and the battery kinda went south (even though it’s new…).
Haven’t plugged vcds quite yet, but I might have many many fantom errors due to the previous battery that was weak and now this one.
I notice that the Y plenum is cracked, the former mechanic that worked on it cracked it and hid it like that after applying some kind of glossy coat on the crack.