Strange sharp noise at about 1800rpm

[andrassziffer]

Hi,
Z4 e85 2004 2.2i 230k km
There is a strange sharp noise at about 1800rpm in every gear (especially in 1st, 2nd and 3rd), the noise sometimes also persist at about 1100rpm. When the car is in neutral, the noise is more quiet and comes at about 3k rpm. I created a video about it: https://youtube.com/shorts/q8MsyyB47No?feature=share. Is it the vanos rattle issue? The sound came from nothing, there was not any transition from quiet to loud.

 

[bigwinn]

I’d be checking DISA flap first…

 

[enuff_zed]

Definitely check that disa valve first or you'll be risking a fair bit of damage.
However, to me it sounds a bit like an air hiss (admittedly hard to judge), so also look for splits in the small pipe that goes into the throttle body just below the disa.

 

[andrassziffer]

Definitely check that disa valve first or you'll be risking a fair bit of damage.
However, to me it sounds a bit like an air hiss (admittedly hard to judge), so also look for splits in the small pipe that goes into the throttle body just below the disa.

Thank you very much, I have just checked it and there is a large split. Should I also replace the DISA since the car already has 230k kms or not necessary?

 

[enuff_zed]

Take it out and check if the flap is loose. If not then it’ll be fine. But it’s easiest to swap that pipe with the disa off so check it regardless

 

[andrassziffer]

Update: I replaced the DISA and the intake boot as well, but the noise remained. Any ideas what can cause it?