I believe it is 100% atmo.

 

I heard about the whole "running rich" problem with using a 100% BOV and was wondering if anyone was using it on a tuned car? When I had my car tuned, its running much leaner than before. I went with this BOV hoping that the lean state would help to counter the "rich" state that it causes. If the 100% BOV's are sooo bad for the car, why do lots of people stand by them? Car shops sell them (make money and thats all) and talk them up to being all that. I know for a fact that no two cars here run exactly the same. What works for my car, may not work for yours. Another thing is the backfiring and lower gas mileage. I heard one small pop while idling down in 3rd gear since the 2 weeks i've had it. As for the gas mileage, haven' noticed any change whatsoever. Wouldn't the 100% be better than compressor surge? Seems like the rich state outweights the beat up turbo. Of course thats just my opinion. I can be completely wrong about this whole topic, but it seems to be a descent mod with small ill effects. I've looked around the net for a while looking for reviews about this BOV and have heard "I love it" and "I hate it! A waste of time." I'm not looking to start anything about this, but shouldn't you buy based on pro's vs con's? I know there are people who buy exhaust based on looks and sounds rather than performance gains. Wouldn't most people buy a BOV if its rumored not to leak at all? How many other BOV's on the market leak? Hell, i've heard even the stock one leaks! I guess its up to you to decide on what you really want you car to do. Show or Go?

 

tuning can't change the fact that air the MAF sensor read, and the ECU expects to pass through the cylinders to be mixed with a given amount of fuel is being vented. When your atmo BOV opens, your car runs rich, period. Very bad for O2 sensors and cats.

 

Air passes through MAF
Air exits BOV
Fuel enters cylinders
no air to mix and burn with fuel, car runs rich

[/Jaws quote]

Basically, the MAF reads all the air that goes through it. The ECU then adds the right amount of fuel for that air. However, the ECU still thinks that the bypass valve is recirc, so when it vents instead, all that fuel still gets injected. It doesn't all burn, which can clog cats and foul O2 sensors, as well as cause a little extra bogging off boost.

 

what if you have no cats?

 

Then you're a soulless bastard who will burn in hell. Other than that, you still have the O2 sensor, lag, and bogging problems.

 

my friend had an hks and turbo xs. they are nice for attention, but he says the transmission and clutching works differently w/ it, a little worse in his opinion. good luck.

 

oh nose.

Going to take mine off right now.

*runs out*

 

The stock divertor valve also helps with performance because durring the shift the diverted air "pin wheels" the compressor wheel and keeps the chargepipes/intercooled with some pressure in them which contribute to keeping lag down.This makes more of a difference to the guys with FMIC'S that have way longer chargepipe tracks and bigger intercoolers.

 

Better have good running engine then stupid whoooos sound especially if this is just for effect and didn’t do anything to performance. $300 spends for nothing… better adds another $100 and gets something like Perrin Fuel Rail Kit. I didn’t know about other cars but WRX STI doesn’t need BOV it’s already have one.

 

Good answer. I've closed this thread because the question was asked more than two years ago.

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