Emission are now gone and I have an aftermarket Bailey BOV. The hose input to the valve is connected directly to a vacuum port on the intake manifold.

Every time the engines running the BOV opens up, Therefore no possibility of boost and a massive vac leak.

Obvoiusly the vacuum is holding the Valve open, So should it have a cheack valve in from the intake to the valve so the valve only see's positive pressure?

 

Ok thinking about what the BOV is and what it does I have just realised that it does need the vacuum.

When you let off the throttle the intake see a vacuum and the turbo side sees boost, this allows the BOV to open.

At idle the intake side and turbo side should be equal therefore the BOV should be closed due to the spring. So why is mine open all the time?

First drive of the car and BOV worked ok for first 10 mins then stayed open.

At first i thought it was just stuck open, so cleaned it. Now it open when engine is running and closes when engine is off. I just dont get it.