jvog

So I got a vacuum block to make sure my vacuum source for my bov/boost gauge. Im still only getting that fluttering sound (indicating boost being pushed back into the blower, meaning my bov isnt opening). The bov spring is as loose as it can get. Its a cheap ebay bov so that may be the problem, although must people say that work for a year or 2 without breaking. Any ideas?

ESG-642T

I'm guessing you just got a "bad" eBay blow off valve... T your boost gauge and the bov on the same source if the gauge goes into vacuum and the bov doesn't open fully its prob the cheap junk eBay bov

tws1098

just run a boush bypass, bov's pointless on a supercharged car anyway. It can serve a purpose at higher boost levels but for the most part is a misunderstood piece to a supercharger/turbo kit.

jvog

I am running a blow through maf so a bov is what I should be using.

tws1098

Did you change it to a blow through to run a FMIC? From what i understood they came with a draw through and used a bypass. My bad for the misunderstanding.

livefast1

my obx bov works fine, is yours open at idle (mine isn't btw and from what i understand shouldn't be)? does it flutter when you let off the throttle or under boost?

jvog

It flutters when I let off the gas. Instead it opening to release the air its gettin pushed back into the blower. I think I'm gonna order a greddy bov tonight

Blk003GT

no no wait on that. my buddy just got a supercharger put on his 02 M3 and at first when he would let off the gas he got the same fluttering sound. now he had his bov(bypass valve) vented into the atmosphere instead of being put back into the intake which will raise intake temps. what i think happens is that on the bov there is 2 spots to hook vacumm lines up to. (on his) one is for a boost line and the other is left open. (we initially had both hooked up to boost which caused the fluttering. we then only hooked one up to boost( the lower one) and left the top one open and the fluttering went away. it has nothing to do with your bov its how your boost lines are conneced into it. off the gas boost is going to come out since comming down from the rpm's your still in boost so it still is going to need to bleed out boost. but you shouldn't hear the fluttering it should be more of a constant air noise comming out when you let off the gas. so check your boost lines maybe call whoever you got your kit from and make sure your bov is connected right. hope this made sense. plus i'm basing it off of an m3 but its the same concept.

jvog

Yes my bov has two reference ports. I have the one on the top hook up, and the one on the bottom left open which is how it should be hooked up as far as I know. Sounds like you have yours the other way around. Hmmm

jvog

"There are actually two reference ports on the back of this BOV. The larger one (on top) is the regular reference port to be connected to the intake manifold. The lower port is meant to be connected to a source in your intake before the throttle body to help the BOV open more quickly and be louder, but we doubt this really works. We recommend leaving the lower port alone with nothing attached to it.
If the reference ports are pointed in an inconvenient direction, you can remove the 6 bolts on top of the BOV and rotate the top part of the BOV until the ports are facing in a better direction, then reassemble. Use caution when removing BOV top as the spring will try to throw the top in your face."

Got that from siliconeintakes.com