This is a common myth. The system is dependent on 1) the TPS signal, and 2) the BOV itself. Modern fuel injection system do a fuel-cut on decel to 1) save gas, and 2) alow the revs to drop faster; the fuel-cut decel should override any fuel delivery (issues). If the TPS is slightly off, it'll keep shooting fuel on decel - this is how you get the popping on decel or in between shift. If the BOV doesn't seal fully (which it sounds like this is the case in this video), you get an intake vacuum leak - what were the vacuum #'s before and after the BOV install? Was it the same? I've seen plenty of BOV's that leak on WRX's / STI's... Making a BOV that 100% seals at idle makes it more expensive to produce. If the BOV is sealed 100%, the system is closed, and your idle should be identical to before - the fact that you're running rich means something else has changed. This is why some people have no issues, and why some people do have issues.
I was gonna say I bought my 19 wrx used that came with an HKS BOV and it’s closed system, i didn’t think it had a MAP for it installed already but I don’t have any idle issues what so ever since purchase. Seems to be working A OK. Still need to get an AP for her but other than that no issues still 🤞🏻🤞🏻
2 года назад
I'm not that sure. I have a Suzuki Swift Sport ZC33S (from 2018), and I installed recently (a month) the HKS SQV IV valve and I'm experiencing some of the symptoms that he says. Today I'll mount the recirculating tube, to see if that mitigates the lagginess and stuttering in very low revs, like when I'm in the middle of heavy traffic. Saddily I'll lose the high pitch sound, but in the long run I prefer to not to damage the engine.
Idk man, I know science is science but I’ve owned 3 Subaru’s, rocked a BOV and OTS tune on all 3, put easily 75k+ miles on all 3, and had 0 issues related to the BOV. All cars were tested and healthy at time of sale. Maybe I’m just the lucky statistic 3 times over. Nice video and very informative though, keep up the good work
I've seen some cars respond different using OTS Tunes, if you have a higher quality valve it would mitigate out some of the leaking issues that other valves have had.
Right. I just installed a fully atmospheric bov on my 2018 sti and I didnt have an of these issues that smeedia has. Maybe theres some underlying issue causing the knock in this video? I installed mine after watching and did little revs like this and not a single issue. Maybe its cause his bov spring was too loose and was by passing even the slightest bit of pressure? Maybe it's not having that long pipe on the ic piping for the stock bpv location? But I dont think that knock issue is directly because of installing a vented vs recirc valve.
@@enemen8 The car is not designed for it, doesn't mean you can't get away with it. Typically the Supreme crowd or "younger" crowd throw them on without knowing anything, go get a tune and ask for the "Can i get a dope crackle n pop tune with a touch of flames out the exhaust, bruh?"
Hey man, there is no way that it would make a difference running that low RPM, The BOV only opens up to let the air out when the boost pressure is above 0 (Hence the BOV sound). Anything below 0, you should not even notice the difference because it's a closed system... So with all do respect, what you are saying does not make sense. If its open below 0, that would indicate a boost leak.
especially when running something like the GFB TMS Hybrid. Zero chance you’re gonna mess up the closed loop system if you’re setting the spring tension correctly. That’s literally it.
MAF measures the mass of air that enters the engine. Speed density calculates the amount of air that goes in the engine by measuring pressure, manifold air temp and rpm. You must use a float valve style BOV that does not stay open under vacuum. If so you simply need to change one number in the tune. His engine is actualy over correcting for running lean because its sucking in air at the BOV.
I did a ton of reading about speed density vs maf tuning for my lt1 corvette motor. Same concept different platform. I’ll see if I can find the link, it’s a ton of relevant information to the topic
See, its a missconception. You can use a twin piston/diaphragm type atmospheric bov on maf setups and they work as perfect as they do with the recirc valve. If you were car guys youd know this... Ive run a loud bov on every turbo car ive had and all being maf setup. Do some research and stop talking shit.
I just installed the AEM chargepipe today and realized at the end that those suckers didn't include the recirculation hoses as the AEM relocates the BPV on top of the engine...same situation...car runs way rich with CEL P0170, car stalls when coming to a stop...smell of rotten eggs...waiting on delivery of the hose...thank for the video this clears things up...i swear you da best! And the only youtuber I came across that responds the same day lol....Bless you bro
"I'm scared because the rpms are dropping low" probably because the ecu is trying to re learn everything. What exhaust is that? Kinda sounds like dookie
Hey Tanna, it's UK Subie guy. Waw, it's been a long time from this video, & You buying my dream car for the next chapter of the channel. I really like seeing the influence you give out in every video, no matter how hard the next part instal/removal. There are so many Great car covered ytube channels adopting your style & weeding out the fake weekend mechanic. Gracias mi amigo 🇬🇧🤘🤘🤘🤘
I have an fully recirculating hks bov paired with a cobb big sf intake. E-tuned by William Knose at Delicious Tuning by the way. In my opinion, this is the way to go if you want those spooly boy noises. The stock airbox muffles alot, so you can certainly hear the bov noises through an upgraded intake. Side note, my hks bov is a 13 year old original version from 2007, that was still brand new in the box that I never used for a prelude build I never finished before joining the Marines.
Also you said that the extra fuel would get into your oil as it ran down the cylinder wall. You would have to be running insanely rich to have left over liquid fuel in your combustion’s chamber(like 5:1 gasoline). Also your wideband afr gauge on the right side of your steering wheel was reading anywhere from 14.5-15.1. Not rich at all as the stoichiometric air fuel ratio of gasoline is 14.7:1
Been running my bov for 18 months on 380 HP wrx. No issues at all.. I stay up on maintenance, and plugs look normal. I recommend getting one if you want.
Did you get produced with it on the car? The major issue of it is using a BOV on a Stock car or one with an OTS Map which already have their own issues with them.
Id guess you done have it setup right. My GFB Hybrid BoV was installed by a master tech at a Subaru dealership and I have 0 problems. Its running about 50/50 recirc/vta. Also its only going to "run rich" for a split second during a high rpm shift. If anything that split second of rich is going to help vs engine knock. Its been on the car for 2 years (35k+ miles).
Thanks for clarification! This is my first Subie, and I have often wondered what would happen if you put a blow off valve on a stock car. As soon as you turned the ignition on I could tell she wasn’t happy at all lol. Thanks for everything you do for the channel!
I just bought a side project car and its a used 2013 WRX STI Sedan Sporttech usualy they go for around 17K + I got it for 10K 1.has very small body work to do (only minor rust spots) 2. needs a new paint job 3. The car runs but dosn't run well. Coming from the dealer that I bought it from every time I hit the stop sign or light that choking issue 9:01 happened. I stalled at 3 stop signs.... Got home opened up the hood and the air circlation hose is cut and plugged... stock BOV... So I got on to watch videos on Bypass valves and blow out valves and I want to say thank you! Easy fix just need to get another hose! Thanks for the info @Smeedia
Hello again! Thanks for the information in this video. I finally got my COBB titanium exhaust with j pipe, intake, and access port for my 2019 STi. Super excited to install this weekend. Thanks for all your videos. Next will be AOS... crazy install for that.
I was told that having the j pipe I might need to add a boost control. Said sometimes with the j pipe the boost in 3 and 4th pulls can be too much. So might have to get that installed as well.
Another great video you could do is a very detailed video on how to properly jack up your 2015-2020 Subaru STi. Show all jacking points and where to place jack stands. No one really has a good video for this and some are too short. Just an idea.
your short trim/ long trim numbers will go crazy. When I had mine vent to atmosphere. When I let off the gas, it does -25 percent for like 1-2 seconds. Btw keep up the good content.
This actually helped me a TON. Since buying my car it has not had the recirc hose and it has never idled right. Heading out to a place tomorrow to pick one up and see how it runs! Appreciate you!
Great Video! A few years ago I purchased a RFL blow off valve, had it installed with the idea it was a plug and play, I was so wrong. No matter how many washers, ( how it said to adjust ) caused the car to stall at every stop, and turn the tail of my car black from running too rich. To make a long story short, it’s back in the box and sitting in my trunk. I wish I saw your video 3 years ago!
Glad that you got it sorted out, and some cars react different than others from what I've seen most think that BKVs are plug and play but so much more to them than one thinks. Appreciate the added sorry and kind words!
I ran a BOV on a stock STI 2018 and had 0 issues. Currently I’m no longer stock and have a Stage 1 OTS tune and it shows no issues I’m not rich or lean, just yesterday I got a -1.40 knock and -1.40 knock learn
I should’ve watched this video before I almost messed up my engine..got a 2004 wrx and installed this bov the whistle so freakin nice but after few months the sounds started to go down until its gone and after that i startedto hear like fluttering noise from my engine and dont know wth is going on even my mechanic got headache i gave him tylenol..please listen to this guy and dont install that piece of crap.🤓
The cars not going to be driven for a month and will be returned before driven but not a bad idea, also can let the ECU relearn by driving normally for a bit
Smeedia yeah 15 minutes is about what it needs to relearn. Your setup was def not happy with the hks bov I’m surprised it affected idle, wouldn’t it be closed at idle I tried to run a GFB fully adjustable bov but it works differently to Evo x oem bov (not sure how) Even though spring pressure and venting is adjustable I didn’t like how it felt or sounded GFB can be set to fully recirc, but still to different to what car is expecting Definitely need to tune for these Aftermarket bovs Check this out, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bsy9hJic7cQ.html
It was odd, if only effected idle under load, if I was strongly and not moving it did not change anything. The cars getting torn apart tomorrow until the pro tune, if I was driving it again soon then I would go through the relearning process. Car def did not enjoy that 😅
The BOV isn't what was causing your issues at idle. How could it when there is no boost to blow off? Regardless, you can't tune for a BOV. I get really tired of telling people that. There is no special table for "WOT release" or anything. They do slightly increase how rich the car runs for that brief moment when letting off the throttle, more pops and bangs, which in turn can hurt the cat and turbo since those explosions are happening nearby.
With Speed Density, there is no tuning you can do either. It's just that the reference of MAP is a lot closer to the injectors than the MAF is, so there is a lot less time of fuel squirt at WOT release. Anyway, I am so sick of BOV arguments, and this video makes it worse. 175k views and counting ;(
@@sssnake2332 Thanks for the explanation! I bought my '18 STI a little over a month ago which came with a GFB bov, and I've been reading forums on the subject ever since. I don't have any of the issues that Smeedia was having in the video so I wasn't too sure what to think. I love the sounds my bov makes, but I'm not going to keep it on at the expense of my cars health... :C RIP 😢
On my 04 wrx with an ej20 I had an hks bov and the car ran fine up til 170,000 miles and the only reason the car died was because it was crashed and totalled. Never had to replace a cat and the car never left me stranded once and I had no idle problems. I did have a turboback exhaust, intake and a ots ecu flash tune. Now with my 2022 wrx I don't need to do it for the sound because the stock bpv makes a lot of whistles and whooshes and some nice turbo flutter by just replacing the intake.
See great information about everything. I'm new to the channel and I'm really impressed with the knowledge but I'm impressed about everyone in the Subaru community doing these videos on our beautiful platform. Keep up the good work brother. Stay safe and have a good week.
So I'm new to cars period. I just ordered a 2021 WRX Limited and I want to learn all the things. I took a quick course they offered on post to learn basic engines, watch some videos to learn about the turbo, boxer, direct injection, etc. My understanding of all this is very very basic. If I'm watching this saying, math based car? Speed density? Blow off valve? Charge piping? Where can I start to learn about all these things? I got a little overwhelmed when I tried starting with nasoic. Long road ahead but I want to know. BTW I'm a nurse so I'm literally starting from the ground up. Thanks!!
This video makes me laugh lol “the car smells rich “ I installed a hks bov on my sti and had no problems honestly it’s running great, Talk to your tuner.
As long as your not on an OTS Tune with the BOV its not a huge issue. A protune fixes a lot of the out the box issues associated with just slapping one on
Smeedia I believe I’m on a OTS tune at the moment, I have to talk to my tuner but it’s so weird that your car has symptoms like that. Have you had any updates on it?
I pulled the BOV off the car after the vidro and stayed with the bypass valve, im going on a hybrid speed density tune so because I am still utilizing some of the MAF I'm sticking with thr BPV. But based off of what I did im sure the BOV was leaking air causing idel to be all screwed
Smeedia I would like to come help you maybe the rubber inside the inserts were not tighten down? Or the rubber seal bad? Also my kit came with a recirculating kit with my hks bov, if you want you can try it on your car if you wanna run the hks!
I only used the BOV as an instructional piece for the video to demonstrate the effects of an out the box BOV on an OTS TUNE. But greatly appreciate the advice!
Big ups to Tanner for willing to use his car as a guinea pig to show what not to do. Alot of people still dont understand a stock MAF setup vs a MAP setup.
Just replaced my FP blue with a dom 2.5 xtr, similar but seems to spool louder and "hit" a little bit harder. Only replaced because mine had a hairline crack that made the car smell like burnt oil. The FP blue looked and felt like a stock turbo which is why I liked it.
This was a good laugh. I ran a vent to atmosphere bov on a decently modded, not built 7 bolt 22psi 2g awd dsm from 60k-280k miles. To counter this, I ran a k&n style breather after the maf. My af gauge read super rich before the breather. Came back down to not so rich and good levels after. If I did it again, I'd go dual port. They didn't have those available back then. Worked for me. I'm pooping at home. 💩
Makes no sense. If you had true in depth knowledge on this you would know that installing the bov wouldn’t change the idle of the car one bit. The only time the blow off valve will effect the air fuel ratio of the car is when there is pressure built up in the manifold and then the throttle is closed (during shifts) although I don’t run a bov on my car because I prefer the performance gains of a bypass valve(keeping more air in the engine during shifts) they will not hurt the car. As you said they will make it run more rich during shifts which may foul spark plugs faster but really won’t make a huge difference. On top of that Subaru’s use open loop fueling once in higher loads even when you are pro tuned with a cobb. Open loop fueling uses a target air fuel ratio or lambda and can very slightly adjust injector duty cycle to change your air fuel ratio and get it back to normal. Also you mentioned that the car showed some amount of fine knock learn when you were leaving the driveway which cannot be due to the bov. Fine knock learn is a ignition timing adjustment that the ecu makes over a long period of time when it tends to see knock at a particular load and rpm. If the bov was causing some sort of detonation, you would see that in feedback knock which is a real-time adjustment made by the ecu immediately when it senses detonation. Just thought I’d give you my .02 since I have built a few of these engines and tuned a couple
the "bypass" valve is a BOV that is recirculated, its not a "bypass valve" its just a BOV that's been designed to recirculate the air back into the system there are also BOV's designed to do both at the same time like the Turbosmart BOV's .. in Australia its illegal to run a BOV Vent to atmosphere..
@@Smeedia Tell me about it. If I had a dollar for the number of times I had to drive 10min+ out of the way to go around a stopped train I could put new Garrett Turbos on both my 95M and 96 Miatas and not the GT2554R and GT2560R I have now. lol
I have a 2015 wrx and have been running a bov for about 4 months never had an issue that I felt the car was in danger and overall it has ran better than it did before.
The Ecu does take a little minute to calibrate it...... If you have the accurate back pressure it should be OK. Does make some good or bad depending on you. At super high revs. That's a good thing to monitor. But... Put anything on it.... Go get it tuned. I'm not smart enough but there's always a dude that is 😅 love the vids man.
I have a 2004 wrx and put the hks bov on and now the engine is throwing engine rich code and cylinder 1,2, and 4 misfire i put the bypass valve back on. how do i know if the damage was made or will the codes go away after awhile?
If you setup BOV correctly the car will not idle or run ANY different, unless you did it wrong then it will idle differently, or its a POS like that valve, If you can smell fuel or it runs different you done screwed up and not installed it correctly or its not adjusted correctly, during idle the valve is 100% closed and doing nothing so wont effect anything. (High quality valves like GFB Hybrid are the best and cant even leak even if 100psi boost) Makes almost no difference it only runs lean for 0.15 - 0.3 seconds when you let off the gas and as you are not making power it does not matter if AFR's goto full rich If coasting down a hill in gear AFRs are meaningless as injectors are shutoff during coasting. Even the guy who started the rumor in the UK admitted to it after like 15 years that he was just making it up as he hates all the ricer Subarus going around making blow off noises (Ricer/Racer boys) It all started from him and was just a joke, Just like the DR who joked about Vaccines causing Autism in a paper he wrote and accidentally started the now stupid idea people have that its real, Even year later when he said it was just a joke in the paper he wrote people wont believe him and say he must have been paid out by Big pharma. Put it on dyno and watch the lean condition is so short if you blink you WILL miss it as human eye takes .25 seconds to blink so easy to miss a rich condition that last .15-.3 seconds. If you are serious about tuning should be replacing the plugs every 10,000KM as they will be copper spark plugs which are best for fuel burn and so on.
Still baffles me why Americans refer them as blow of valves and by pass valves.... makes so much more sense to state it as vent to atmosphere or recirculating bovs No explanation needed once you state them that way!
Is there a Cobb tune that lets you run a BOV? I’m looking to get one but there’s no videos really explaining how to tune for it just a bunch of people saying don’t do it with a stock tune but obviously there is a way to tune it
After the rich cycle you get a lean cycle that follows which is thr main drtrement to the engine, but a tuner can mitigate that to a degree during a protune
what about just blocking your bov and having compressor surge. obviously a bypass valve would be better but would no bov be better or worse than having a bov
If tuned accordingly is the bov still worth it? Or is it better just having the bpv overall even if tuned properly? I want the sounds but definitely wanna keep the engine as reliable as I can
@@jacksonramboldt4449 I’ve had a gfb respons on my ej20 for ages with no issue, 30/70 atmospheric and recirc with a few adjustments to the valve spring tension to get it perfect and it runs like stock plus the cool noises
@@nes3382 in the exact same boat here. i love the GFB and have it set up the same way as you. Its definitely worth it to get an adjustable BOV like GFB or turbosmart!
@@Smeedia any suggestion on brand or model downpipe for my 2021 STi? the carb legal one.....thanks by the way for answering your viewers questions, you always take the time. wishing you more success on youtube, watching your channel made me decide and buy STi! youre gonna do great things!
I bought my 12’ STi with a BOV already installed (and intake and exhaust) and a protune. Seems to run great, anything else I should look out for or be worried about? Knock monitoring is all within normal limits. I’m straight ricer and dig the noises. If it’s okay, I think I’ll keep it. Will have tuner check out car just to be safe. What do you think? It’s just tough cuz there’s so much polarity in this topic… hard to get a straight answer
My dream is to do no bpv or bov on a speed density tune just for the turbo flutter and slight weight savings lol. I agree on not using one on maf, but at least you'll shoot some flames!
I got a 16 sti with the same hks bov and when I rev it the car wants to stall out and I failed nj inspection cuz the evap and oxygen sensor wasn’t ready
How urgent is it that I get it professionally tuned right now I’m running a stage 2 + BIg SF 93 ots I have cold air intake, MA performance J pipe, nameless catback exhaust system
really wish there was a video like this last year. I bought a 15 sti put a bov on and drove it until last month now I need a new short block cause cylinder 4 piston failed.
@@Smeedia when I get the short block installed get a cylinder 4 cooling mod, down pipe, and tune that is all until I pay the car off. afterwards, the sky is the limit!
Made it to the tuner today! Hopefully I'll get it back this week 😬😬😬 Its been down for 2 months, it was so nice driving it again... even though I had to take it super easy Iol
Good god that train. 😂 You have been educating me sooo much about Subarus. Gonna lease one soon. At least i know what to do and not do. I feel like more people who are into BOV need to know this or those who are going from a BPV to BOV. To each its own right? Great content.
Exactly, people are totally free to so as the please with their mods, but agreed I at least want people to be aware of the potential issues of using one. And glad the videos are helping my friend!
