how to check for a faulty bov

Well, first thing you do is turn the car on and physically look and listen to the BOV. Listen for any high pitched sounds that indication the piston is not sealing properly and therefore leaking air. Second thing is to use the cable near the throttle body to rev the car a bit or have someone rev it while watching the BOV. You should see the BOV piston moving up and down as it moves down to close off the BOV to retain boost or if it moves up once the throttle is released to let the car release any boost and to allow the car to idle properly.

The BOV diaphram should immediately respond to throttle input. If it looks like it is reacting slowly or not at all, then you have an issue with the BOV.

yeah it dont move at all....would this cause to have low boost

Another test is to take the vacuum line running to it and use something like a mityvac to create a vacuum in the hose, the BOV should hold vacuum.

okay thanks

ohlins8990 said:

Another test is to take the vacuum line running to it and use something like a mityvac to create a vacuum in the hose, the BOV should hold vacuum.

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I just suck on the vacuum line, and plug the end with the tip of my tongue - it should hold pressure, and snap back when you pull your tongue off the line. If the pressure bleeds down or you can suck air through the vac. nipple then replace the valve.

Best,
Drew