So I have a 98 civic ex turbo...and I just started running it and when I drive it around I notice that there is a BOV sound coming from turbo when I rev it aroun 4,000 and up...also my BOV isn't working valve isn't opening up, I opened the vacuum tube to see if there is any air and there is some but not like a lot.

 

if your hearing a bov type noise from the turbo and your bov is not opening then what you are hearing is surge. over exposure to surge can damage your turbo. if your bov is adjustable then you need to adjust the bov to a point where the bov is closed at idle vacuum. the bov will open when the throttle is closed under boost. this creates a larger vacuum spike than you will see at idle causing the bov to open.

 

if you have a spring type bov. then you need to change the spring to a lighter spring rating.