been looking for a long time for anyone who knows what the hell this is .
noise is coming from behind and below the intake on the firewall side .

thanks in advance

 

There is another thread on this exact noise. Do a search for kazoo.

Found it: https://www.northamericanmotoring.co...ering-off.html

 

first off thanks for the help man ! funny thing I got frustrated with this and dug into it and its exactly what I came up with .
new to this forum but a staple in the bmw forums and now that I think about it I should have known but at the time I had no idea where the solenoid was on this car . I will be buying one and replaceing and will report back !!!

 

fwiw after replacing the pressure regulator/boost solenoid whatever you may know it as all is good been a week and no noise . cars seems to be a little spunkier than before and took 1/2 hour or so and 140.00 bucks .

thanks for the help guys and hope this brings closer to the problem