Recirculation Valve Vs Blow off Valve

[Edub1]

I learned a valuable tid bit of info today.

Some valves such as the 1G DSM valve are recirc valves - that is to say that they remain OPEN at idle and only close under cruise / boost. These will create a huge vacuum leak and can not be used for open atmosphere dump. However, recirc is better for a MAF system because of the metered air issue any way.

A proper atmospheric dump BOV should be the type that remain closed and only open when dumping.

Anybody running a open DSM valve and having idle issues?