does anybody know? thanks (mine doesn't make a sound when i disconnect it from the airbox)

 

You need to apply a vacuum to it - 15mm hg and it should open up as best I recall.

 

If it's not working right it will either allow you to build too much boost when backing off of throttle or if leaking would not allow you to build pressure. With no vacuum applied to smal port you should not be able to blow through the large port if you can it's no longer sealing properly.