I just bought a GFB stealth BOV, but all the posts I read say ANYTING you do to an STI make the whole ECU retard, almost all engine functions. I'm just wondering of someone has tried one, and if it has more than normal, expected losses?

 

Oh yeah and I'm a sucker for that ppuuuussshhh sound!

 

yeah thats what i don't want, totally what i'd call a power loss. Umm you don' have any going to re-curc

 

The STIs' have a recirclation valve, not a bov, thats why when you install one you *can* lose power although its not always the case. Also you use a MAF sensor to measure air.

Really simple, On cars that use these sensors they are placed before the turbo (your should be right after your air filter - a black box with wires coming out of it), but the BOV vents into the intake after the sensor, so to make it easy to understand: If you have 10cfm of air going in, your MAF reads that and adds fuel for 10cfm, car works like normal, any air trapped before the TB when you shift is "recirculated" back into the intake stream and your stock car runs nice and fine

If you have an Aftermarket BOV, you suck in 10cfm of air like normal, when you shift 5cfm gets dumped to the atmosphere (that makes the psss sound) but your engine has already added fuel for 10cfm... so your running super rich, that is what causes the stutter stumble effects, especially while shifting. Aftermarker recirculating valves dont typically have this problem since they function like stock.

Ways around it, stand alone EMS, or things like an HKS VPC (Vein pressure converter) that measure air differently and later in the intake stream, instead of a "flapper" door style that measure air before the turbo(I believe that is what you have on your cars.) These measuring tools typically measure later in the intake stream (closer to the TB) and so it doesnt matter if you dump all but 1 cfm of air since it will only read 1cfm is going in the engine,

FYI the HKS BOV is a very good BOV especially if you vent it back into your intake stream since the pressure holds the BOV closed instead of pressing against a spring like most standard BOV's that, if you have a weak spring, can cause leaking... and since its operated by a vaccum it opens and closes VERY fast, which is why it typically does not cause a reaction as extreme as other aftermarket spring type BOV's when shifting since you dont run as rich for as long.


HTH's

 

yeah well i had an ssqv, but the stealth has an adjustable amount of boost being recirculated. I'm just worried that the of the computer sees something all "off" then it will make big losses by retarding all the fuel to make up for the stumble. I hear the finiky computer will loose twenty hp with a cold air intake.

 

I don't think so! maybe some one has had good luck with one, but there is no boost recirculated. this will make your car run rich for sure, my stealth BOV is set at 20% atmosphere, I haven't adjusted the spring rate enough, but it works pretty well. My idle is a tiny tiny bit rough, but i'll play with the spring tonight. I had an ssqv on my rex and it was the hit though, the car felt pretty much the same as stock. My friend said when he put a GFB hybrid on his it made his car lag more between shifts. I already had that ssqv and so I sold it before I got the STI.