"The BIG BOV thread" (Where all bov question threads get merged)

[stu]

no it is normally closed and opens between shifts. if it was the opposite of a bov then it would not work to relieve pressure and would close during up shifts causing compresser surge. I have had it like this for six months and no problems

[Hot_Dog]

Actually during light thottle and idle the stock valve is slightly open and will suck in air. The spring in the stock BPV is not as strong as aftermarket valves that are designed for atmospheric venting. There are a ton of threads on this topic, so do a search.

[blarg]

no it is normally closed and opens between shifts. if it was the opposite of a bov then it would not work to relieve pressure and would close during up shifts causing compresser surge. I have had it like this for six months and no problems

the stock valve uses the vaccum signal to close, so when you're idling, the valve is open, when you start building boost, the pressure in the "signal" line causes it to fully close, and the pressure of the compressed intake air keeps the valve closed. When you lift off, the vaccum in the signal line causes the valve to open again, releasing pressure. The leaking at idle has nothing to do with a weak spring, it was part of the design. I've comfirmed this with an SOA mechanic, you do suck unfiltered air at idle through the BPV, which can mess with your MAF readings even more...not only are you blowing out metered air, you're also bypassing the MAF at idle which CAN cause you to run lean at idle and right when you get on the gas. I don't know how BAD it is having never done it myself, but at least in theory that's what happens.

[blackshadow]

I did 4 sessions at a road track today, and when i opened my hood i found lots of oil, that had been ejected out of my BOV and i found oil all over the top of the block as well as on top of the turbo inlet hose. The oil got everywhere. It also happens to be right next to where my oil pressure sensor is. Do you guys think it might be leaking from the sensor? Or is it more likely that the seals on my turbo are blown?

[SD_GR]

Either or neither. Check anyway and let us know what you find. Keep in mind that when you repeatedly go from 100% and full boost to 0 throttle and standing on the brakes, then back again all over and the car is constantly under g, weird things can happen to fluids. Hopefully it's just a loose plug or clamp. Also check the feed line to the turbo and the PCV valve. If it's a real mess you can remove the intercooler and clean it out carefully. That'll give you a better look at a whole bunch of connections anyway.

[j69raw]

I just installed my RFL bov and my engine died twice while I was in the drive thru at McDonalds. I guess I need to install more washers or go back to stock!

[kessler89]

i am/was running 3 washers in mine with no problems along with my mods listed below

edit. turing the top of a TXS rfl bov will not change the tension on the spring, you have to put washers in it

[papastone]

my friends sti ...
he got the stock bypass valve.. disconnected the 2nd big tube that goes into the intake and plugged it up with some plug thing from a shop .and left the opening of the stock bypass valve open( the opening that was originally connected to the "bigger" tube that connects to the intake) so the air comes to the atmosphere. is this just as bad as blow off valve or worse.. or any ideas? sounds good.. but to risky to try my self?? any one?

[§tï]

1,000,000,000 x worse. I hope he doesn't mind buying a new block. Who would do that to sti ...c'mon

[papastone]

that bad?

[§tï]

If it's the same thing i'm associating it with, yes. If not, still sounds like a horrible idea.

[dark_rex]

let me guess...


he wanted the cool psshhht sound.


<sigh>

[papastone]

whats so different between a bov in 100% atmos. mode and the way he did it?

[Elm]

I tried that with my stock bpv; Its loud as a mofo(even compared to my hks it was loud) , my car wouldnt idle correctly at all, and would be very hesitant between shifts. My HKS SSQV on the other hand is flawless

[dark_rex]

whats so different between a bov in 100% atmos. mode and the way he did it?

nothing. they're both pretty bad ideas unless you're dyno tuned for it along with a series of other mods. the ecu is running air, fuel and timing based on certain parameters expected to be in place. if those parameters are not in place (such as a certain amount of air being rerouted back to the intake) it will not run optimally.

dR