Johnyquest

Guys, it really doesn't matter what your BOV is doing at idle. When under boost, that VAC line has pressure in it... and pushes it shut from the top under boost, stopping it from leaking. When you let off the gas, the combination of vaccum at the top of the valve and pressure in the charge pipe works together to pop the valve open. At idle, who cares?

baldur

Diaphram valves intended for recirculation tend to be open at idle. Piston valves intended for dumping into the atmosphere tend to be closed at idle.
If you have a diaphram valve that's open at idle, there are a few things you can do.
- plumb the valve into the air intake, which is what you should do if your car is equipped with a MAF. That or ditch the MAF sensor, it's only a restriction in your intake anyways.
- Put a small air filter on the valve vent, so it only draws filtered air.
- Use some check valves and stuff like that so the dump valve only sees vacuum in the right circumstances.
- Same as above with a 2-way solenoid and a simple electrical control circuit.
- Get a valve that doesn't open when there's no positive pressure in the intercooler plumbing.

BlinD

Ok well since all this has made my mind mush from confusion. I read my RFL instructions and said the piston should be closed at idle. And if its open add washers as necessary to close it. So I guess it should be closed?

baldur

yes, you don't by any means want the engine to draw unfiltered air through the dump valve.

turbocivic17m

mine has always been slightly open. I would not worry about it, who gives a flying ---- what the thing does at idle..... just make sure it opens during shifts

Nick7

Mine is also open at idle.. on the other hand - there aint that much difference in vacuum level from idle to when decelerating, compared idle vaccum to atmospheric pressure.
On my gauge highest vacuum is read as -1 (it reads in bar), idle is at approx -0.75 - -0.8bar. BOV starts releasing air at about -0.5bar.
As for sucking in things thru BOV.. heh, no go, even at veeery low throttle, when you still have high vacuum - thus BOV is open, turbo is spooled somewhat and pushes air out thru BOV.
Just rev it at some 2000-3000rpm in neutral, and check that BOV is actually pushing air out, instead of sucking it in.

BlinD

Well so I added 3 washers. Its slightly open but closed for the majority at idle. Seems to pull a little harder in boost but that could be all in my head. Oh well haha.

Nick7

It's in yr head .. at boost EVERY BOV is closed. Unless it's completely broken...

RENR

my hks bov is closed at idle....

BlinD

you have the ssqv? Happen to have a sound clip or video. I've been dying to hear it on a honda.