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A.X.D.
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thanks for the post. it was helpful. ;)

because...

the air is metered by the MAF and the BOV dumps the metered air out of the intake system.

this causes the car to run rich between shifts because since the air that was metered by the MAF had the proper amount of fuel added by the ECU, now you're dumping out the metered air (via BOV) and leaving the fuel.

that causes the rich "spike" between shifts.

will your car die from it? no. will it backfire and become less smooth between shifts? yes.
 

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thanks for the post. it was helpful. ;)

will your car die from it? no. will it backfire and become less smooth between shifts? yes.

Anytime :lol:



I do question your last comment due to experience with friends car. My friend had a 03 wrx.. mods consisted of a BOV and a borla catback. After 20K on these mods, he started to surge a lot between shifts. Needless to say, about 20K after that his car go boom. Those are the only mods that I knew of, so maybe he did something that I didn't know of. But every car reacts different, just keep that in mind. But if you run rich for 50K miles, that can have a major affect on your motor. Sad thing is, I warned this guy repeatily about removing that stupid BOV and he didn't listen...
 

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A.X.D.
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that's a pretty big stretch to relate a car going boom from a BOV. being it wasn't your car and you didn't know what else may have been done to it, it's best not to start another urban legend for the BOV. it was probably something else that caused your friends car to grenade.

i have had a 50/50 venting/dumping BOV on my car for about 25,000 miles and have never had a problem with the engine from it. i have been tuned with it so i know for a fact that i am not running as rich as i did when the car was stock. in fact, the only time you will run rich with the BOV is in between shifts, not all the time. also, a good tuner can help clean that up for you as well.
 

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that's a pretty big stretch to relate a car going boom from a BOV. being it wasn't your car and you didn't know what else may have been done to it, it's best not to start another urban legend for the BOV. it was probably something else that caused your friends car to grenade.

i have had a 50/50 venting/dumping BOV on my car for about 25,000 miles and have never had a problem with the engine from it. i have been tuned with it so i know for a fact that i am not running as rich as i did when the car was stock. in fact, the only time you will run rich with the BOV is in between shifts, not all the time. also, a good tuner can help clean that up for you as well.

Well i know he wasn't tuned as he always said he needed to get tune sometimes soon. Plus I am sure he didn't play with the settings on the BOV to make it work to its capability. But you can't say it is health or even bright to run something that makes you run rich. You are better off running an intake, especially if you are going to be tuned. It is proven that a car tuned with an intake can produce nice mods. And unless you are running big mods, BOV are just noise that wil make your car run like crap.

As I stated early, his car surged between shifts. None of which happened until after he put on the BOV.
 

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A.X.D.
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Well i know he wasn't tuned as he always said he needed to get tune sometimes soon.
sounds like this was surely the reason for his car's demise.

Plus I am sure he didn't play with the settings on the BOV to make it work to its capability.
there shouldn't be any settings on a BOV/BPV to make it run better. you can ether tighten (or loosen) the spring to allow more/less pressure open the valve to dump the charged air.

But you can't say it is health or even bright to run something that makes you run rich. You are better off running an intake, especially if you are going to be tuned.
not that it's good to run rich or lean, but it's much safer to run richer than leaner as running leaner will increase likelihood of detonation/knock events. you should only put on an intake if you are on your way to getting tuned as fooling with your intake calibration tables is NOT a good idea unless your tuner is doing that for you.

It is proven that a car tuned with an intake can produce nice mods. And unless you are running big mods, BOV are just noise that wil make your car run like crap.
i had to upgrade my BPV because i went with a bigger turbo and was running over 22-23PSI. the factory BPV has trouble holding that much boost unless you crush it, and it wasn't (and still isn't to my knowledge) a science yet, so i didn't want to risk damaging it and not having something exact.

As I stated early, his car surged between shifts. None of which happened until after he put on the BOV.
sounds like the car wasn't happy with the parts it had on it and the ECU was trying to fix it (but could only compensate so much) and was thus unable to put the car back to maximum happiness.
 

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i had to upgrade my BPV because i went with a bigger turbo and was running over 22-23PSI. the factory BPV has trouble holding that much boost unless you crush it, and it wasn't (and still isn't to my knowledge) a science yet, so i didn't want to risk damaging it and not having something exact.
IMO the stocker is more than capable of boost at those levels. I run the stocker and I peak at about 24psi and taper to 22psi to redline.
 

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IMO the stocker is more than capable of boost at those levels. I run the stocker and I peak at about 24psi and taper to 22psi to redline.
24psi on my stock valve here as well. I have run it at 26psi and didn't have any issues.
 

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if you just want the wosshh sound, why dont you just pull the recirc hose off? ( and plug it) why spend money on a show off valve when you already have one? where is my stick, i need to go beat a dead horse or something.
 

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Well i know he wasn't tuned as he always said he needed to get tune sometimes soon. Plus I am sure he didn't play with the settings on the BOV to make it work to its capability. But you can't say it is health or even bright to run something that makes you run rich. You are better off running an intake, especially if you are going to be tuned. It is proven that a car tuned with an intake can produce nice mods. And unless you are running big mods, BOV are just noise that wil make your car run like crap.

As I stated early, his car surged between shifts. None of which happened until after he put on the BOV.

something about these sti's , it seems if you want to change the floor mats you need a tune (sark, u get the idea i hope)
 

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if you just want the wosshh sound, why dont you just pull the recirc hose off? ( and plug it) why spend money on a show off valve when you already have one? where is my stick, i need to go beat a dead horse or something.
bad idea no one do this... STOP spreading bad info!!!!!
 

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bad idea no one do this... STOP spreading bad info!!!!!

so whats the difference in running a aftermarket vta bov than your stock that you have set up to vta? its the same thing. if you plug your recirc hose there is nothing different in either of them.
 

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The stock Bpv is supposed to be open during vacuum even if the car is spooling, if you are crusing and are at light loads the and in between vac and boost the bpv will be opening and closing. This will let metered air out and cause a more constant rich condition which will make the car run like crap. This also happens with some cheap vta bov like tial and Txs. Back when I had a txs bov this sorta ting happened to me and we noticed it when we made a log on a wideband and the af were all screwed up on part throttle conditions.
 

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You canNOT run most recirc valves / BPVs as atmospheric BOVs. Most leak a bit under vacuum, which doesn't matter much if it's recirc'd, but atmospheric will run horribly.

This horse has got to be approaching dust by now...

Siegel
 

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ok so i'm still really confused with the BOV and i'm still new to subaru's and turbos.... i tried reading the posts and it just adds to my confusion.... i bought my 04 and it already had a HKS bov and a injen cai... should i get my BOV taken off??? and if i do do i need to replace it with a part that came stock?
 
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