After hauling *** in my Evo I parked it back in my garage and slightly hit the throttle, I then noticed a very high pitch "whistle". Further investigation lead to my conclusion of that its coming from the BOV.

The whistle happen at like 1500 after letting go of throttle. What could it be?

 

Goes away when my spring is set all the way to hard. Its a Greddy BOV, Not sure what type.

 

Is it a real greedy? It could be you brakes are low .....?...could be

 

wtf?

he's parked in the garage, what does brakes have to do with it?
im guessing the bov spring is weak and its leaking since its gone when u stiffen the spring.

 

Too much vacuum pulling it

 

Ripped diaphragm?

 

Thanks for the input. I'm looking for an Allen wrench that's will fit the bolts to take a look at the inside of the BOV. Im having some suspicion that it is a fake Greddy, not sure. If it is then I'm in the market for a new BOV.