Buzzing as it goes under boost?

[linluv84]

A repost from zcar, not much help there...

 

I did my turbo conversion on my NA motor and everything is pretty good. However, right about when manifold pressure goes positive, I get a momentary buzzing noise (like a bee or a party favor?). I eliminated the bcdd, egr, and even the fast idle doohickey from the AC. The only last think I can think of is the aux air deal. Did the turbo models use a different valve, or could mine just be broken? Any other ideas? There was almost zero shaft play in the turbo, so I'm pretty certain it is something else...

 

Thanks guys, I'm hoping maybe somebody here has encountered the same problem.

[Mayolives]

Are you using a boost controller? I had one that buzzed.

[proxlamus©]

an electronic solenoid will BUZZ if the solenoid if bolted firmly to a fender or firewal.

 

Buzzing would also indicate an off balance turbo, yes it can be within almost NO shaft play and see be unbalanced.

[cygnusx1]

Leaking or poorly set BOV? Pop off valve? Put check valves in all the vacuum lines going to the intake manifold. You dont want boost going into the vacuum lines!

[linluv84]

So if the turbo is unbalanced, it wont buzz continuously? It seems to happen only at 0 manifold vaccum (right around 90-95kpa). It spools up nice and smooth and is very consistant. The only vacuum devices that are hooked up is the vac advance and aux air valve. No bov (yet). I have considered putting in a check valve backwards to use boost to keep the egr valve shut. I guess I will give that a try...