sigh

This is really going to be a train-wreck thread, isn't it?

Well, in my role as a mod, I demand that all subsequent posts that go on about vacuum this or boost that be very clear about which side of the diaphragm they are talking about.

 

Vacuum line must be plumbed to a port past the throttle body. Bov should be shut at idle. A bypass valve(used for supercharged applications) is designed to be stay open at idle. There is something wrong with your bov or you have a synapse bov. Hah

 

My BOV/bypass valves have always stayed closed at idle. Might want to look over your setup for vac line to it or potentially it's got an issue with it.

 

Straight from Tial. Read the last line.

http://www.tialmedia.com/documents/BOVspc.png

The spring only keeps the valve closed at vacuum. Whenever you get into ANY boost, the pressure from the manifold pushes the top of the BOV piston down thus holding boost.