EsubaruJ

How I determine how much vacuum it takes to open the bov?

busa4

go to pepboys, advanced auto parts, or any auto parts store and in the tool isle you will find a vacuum pump/gauge. its 10.00 or less. you use the tool apply vacuum to the bov and see what amount of vacuum it takes to open. put it in place of a hose on the throttle body and it will tell you how much vacuum your engine is producing at idle.

SlowSL

all the vacuum line does is puts equal pressure on the opposite side of the valve when the throttle plate is open, the spring creates a bit more pressure to keep it closed under vacuum or boost, you want that as loose as possible w/out it allowing air to leak. As stated above, when the throttle plate snaps shut, there is vacuum in the manifold and in the vacuum line, allowing the valve to open. If you haven't made a pressure tester for your system, now would be a good time to do it. Using the tester, pressurize the system (don't forget to regulate the air going in to your max psi you want) and make sure the BOV is not leaking, or any other leaks for that matter. Unplug the vacuum line from the BOV and it should open. That's how I would check for proper operation. Good luck!

Snaglefast

Also You might want to take that BOV apart. Those knock offs aren't known for good quality diaphragms.. or anything else for that matter. Check for tears and smooth operation. It look's like you have little spring pressure judging by the pic. I would dedicate a nipple to the BOV (don't tee it). It's always good to use one from the plenum. Or tee off the Brake booster if necessary.

hard2obtain

I think you got a weird problem, try to put your BOV and vac line into another turboed car to see what happens

EsubaruJ

Yeah, this is becoming a real PITA. I can't even test it anymore, for some reason the car wont even start now. I drove it, parked it, and now it wont even crank. I bought a new battery(needed it anyway) and I have power everywhere except to my distributor and starter it seems. The injectors turns on, fuel pump turns on, all interior lights, radio, etc. turns on. I'm assuming its a bad ground somewhere. Its just one thing after another lol. Thanks for all the help though trying to diagnose this problem!