This is the big BOV thread. If you didn't find this thread, you didn't search.
This thread is where all BOV question threads get merged into.
The quote below in this first post is from our BOV info sticky and contains links to some very explanatory BOV information. Please take the time to explore the links before you ask repeated questions.
A stock WRX/STi comes with a BPV (Bypass valve) which is a vacuum-actuated valve designed to release pressure in the intake system when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake before the turbo.
An after market blowoff valve (VTA) does basically the same thing BUT unlike the stock unit it releases air to the atmosphere (giving you the loud sound). Some people see an after market BOV on a stock WRX as being in poor taste (probably due to the fact that it is basically a noise maker that really as no other benefit), while others simply find the sound very attractive.
Proponent opinions notwithstanding, there is a small mechanical downside to having an after market BOV (VTA) on a stock WRX. The problem comes when releasing air to the atmosphere that has already been metered by the mass airflow sensor. When the BOV releases (blows off), the ECU will be injecting the wrong amount of fuel into the cylinders. The engine temporarily runs too rich (meaning too much fuel is injected into the cylinders). This temporary rich condition isn’t typically THAT harmful, but it may cause bucking or hesitation on lift-throttle as well as some other concerns outlined in the links below.
If it isn't a wideband setup, don't bother getting an A/F gauge at all. The cheapy narrow band A/F gauges really don't display meaningful and are really nothing more than a pretty light show. I suggest you spend your money on an EGT gauge instead, much much more useful.
If it isn't a wideband setup, don't bother getting an A/F gauge at all. The cheapy narrow band A/F gauges really don't display meaningful and are really nothing more than a pretty light show. I suggest you spend your money on an EGT gauge instead, much much more useful.
I don't need to a datalogging to prove that BOVs make you run rich in between shifts, it's common knowledge, not to mention it's not hard at all to find any number of cars with catless exhausts and BOVs that have crazy afterfire or even spit flames out the tailpipe in between shifts. Besides, if you know anything at all about how a MAF-sensor system works , and the physical redirecting of air when the BOV opens you'd know it's impossible to not run rich in between shifts. The only question remains is how little or how much...
You say you don't have any issues at all, but do YOU have a wideband and datalogs to prove otherwise?
No, no, no, I know what you two are thinking, it's not the wild, super long crazy flames like they had in the Fast and the Furious, if that's what you silly ricers are thinking. :rotfl: It's more like a very very brief spit of flame that just barely reachs the end tailpipe. Furthermore, it's very hard to see during the day if you aren't looking for it, it's also really only viewable at night. Furthermore, if a cop sees it, you're gauranteed to get pulled over.
he he, even though I'm a nub here and have only had my Rex for two weeks, it is painfully obvious what the general stance is on BOVs, so no worries about me getting one. :thumbup:
:rotfl:
1)Air comes in and is metered by MAF
2)You shift,throttle closes,and you vent to atmosphere instead of sending air in a loop
3)You push back on gas and ECU sends fuel for metered air that is suposed to be there because it never was supposed to leave the intake system.
4)black cloud and firecracker come out tailpipe
5)You go reseach why everyone with an atmospheric BOV would love to have a blow through MAF system.
This isn't even debatable because its a 100% pure mechanical fact.Not to mention probably 70% of the people with BOV's have it incorrectly adjusted anyways.
if it is fact and proven, then show me emperical data. Wideband and datalogging. I have an atmos. BOV and don't get backfires or the symptoms that are always written about. So, show proof that this fact is true...
guy 1: "it is so obvious, you're rich between shifts"
guy 2: "show me proof"
guy 1: "ummm, its common knowlegde, everyone knows noob"
guy 2: "proof?"
guy 1: "wellll.....search, you'll find it..."
well I haven't found it yet :tongue:
It may be true, I willing to believe it. But prove it. I have my stock narrow band but do have logs. its rock solid 11 AFR and then on shift it hits like 26(typical between shifts or off throttle) and then instantly its solid at 11 again.
Before you flame let me say i already bought,tried,sold my hks
but let me ask anyway. i installed my BOV and all that good stuff and it worked but my car ran like piss so i sold it but that return hose... i never plugged it. would that increase my running crappyness? cause i did enjoy the "Cool noise" but not at the cost of performance
if it is fact and proven, then show me emperical data. Wideband and datalogging. I have an atmos. BOV and don't get backfires or the symptoms that are always written about. So, show proof that this fact is true...
guy 1: "it is so obvious, you're rich between shifts"
guy 2: "show me proof"
guy 1: "ummm, its common knowlegde, everyone knows noob"
guy 2: "proof?"
guy 1: "wellll.....search, you'll find it..."
well I haven't found it yet :tongue:
It may be true, I willing to believe it. But prove it. I have my stock narrow band but do have logs. its rock solid 11 AFR and then on shift it hits like 26(typical between shifts or off throttle) and then instantly its solid at 11 again.
If its runnin fine now then prob not but I could be wrong, an expert can correct me. As for running like crap, you shouldve plugged the hose, thats why it comes with the plug.
the biggest problem is that you can suck in unfiltered air through that hose at every throttle lift if its open...so as long as you didn't drive through construction sites or any place dirty you probably dodged a bullet.
basically its like driving around with no air filter.
if it is fact and proven, then show me emperical data. Wideband and datalogging. I have an atmos. BOV and don't get backfires or the symptoms that are always written about. So, show proof that this fact is true...
guy 1: "it is so obvious, you're rich between shifts"
guy 2: "show me proof"
guy 1: "ummm, its common knowlegde, everyone knows noob"
guy 2: "proof?"
guy 1: "wellll.....search, you'll find it..."
well I haven't found it yet :tongue:
It may be true, I willing to believe it. But prove it. I have my stock narrow band but do have logs. its rock solid 11 AFR and then on shift it hits like 26(typical between shifts or off throttle) and then instantly its solid at 11 again.
:rotfl: :rotfl: :rotfl: :rotfl: :rotfl:
Question for ya,as i own a PSI3 data monitor that reads of the stock "almost wideband".Have you ever seen it read under 11:1? I know for a fact you haven't because thats were the stock sensor stops.The factory sensor can not read under 11:1.That's why you saw a "rock solid" 11:1.Now go buy a wideband and see what you get.Most can read down to a 9:1 or lower.
honestly we all know that a bov makes you run rich inbetween shifts but now tell me why thats bad besides the fact that your burning a lil fuel bc i know no one has burt out any o2 sensors or anything like that and have heard of very very few problems mechanically besides ppl who buy junk and expect it to work.
honestly we all know that a bov makes you run rich inbetween shifts but now tell me why thats bad besides the fact that your burning a lil fuel bc i know no one has burt out any o2 sensors or anything like that and have heard of very very few problems mechanically besides ppl who buy junk and expect it to work.
Running rich typically doesn't cause immediate danger like running lean can. The effects of running rich usualy cause problems that show up over the long term. Your spark plugs will foul up much quicker, and running rich can wash out your cylinders which is definately not good. I've been told it can prematurelly foul up your valves too.
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