BOV Vent To Atmosphere
Apr 10, 2006, 03:02 PM
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BOV Vent To Atmosphere
Hey guys
I recieved a free BOV over the weekend, The only prob is that it vents to atmosphere. So me and a friend of mine had some down time, so we hooked up. At first it stalled like i read it would but then we adjusted the spring compression now it makes the cool sound and dosent stall at idle.
I recieved a free BOV over the weekend, The only prob is that it vents to atmosphere. So me and a friend of mine had some down time, so we hooked up. At first it stalled like i read it would but then we adjusted the spring compression now it makes the cool sound and dosent stall at idle.
Apr 10, 2006, 03:06 PM
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shouldnt be a problem on a turbo ES, the reason that VTA stalls out on evo's is because the ECU expects the blow off to be recirculated. On most aftermaket bolt on turbo kits that are put on NA engines the BOVs are VTA. The reason it stalled may have been because the spring pressure wasnt enough to keep the BOV closed and it leaked, which caused the stalling.
Apr 10, 2006, 07:44 PM
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Thats not necessarily true. THe reason why VTA causes stalling in cars depends on the placement of the MAF sensor. If you put the sensor just after the air filter pre compression then the air that is being blown out of the BOV is still being accounted for in the air/fuel readings because technically the car says "ok the air came in, unless theres a leak it can only go to the engine, so lets count that air". It you place the MAF just before the TB between the throttle plate and the BOV then the air is being counted by what is entering the engine and if air is being vented to atmosphere then it is not blowing through the MAF. So basic rule of thumb (if your air flow sensor is placed just after your air filter before the intake on the turbo, then you will need to vent your bov back to the intake plumbing. If it is placed between the throttle body and the bov, then the sensor is reading the air left over after the bov has already vented, so it accounts for what is actually entering the engine. In either case with the turbo'd 4g93 the air flow sensor can still read the air entering the system up to around 9 or 10 psi if placed on the pressurized side of things. after that you are overrunning the sensor and you need to place it on the intake side of the turbo or upgrade
Apr 11, 2006, 07:14 AM
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The reason why the car is working *fine* the way you have it right now is because you probably have the BOV set too hard and it is not pushing out enough air in between shifts. I'm willing to bet you are having some minor compressor surge which is a big no no. If the BOV is set too hard and it isn't pushing enough compressed air out during the shift then yeah, you are running properly because the air that was read by the MAF is still in the charge pipe, however all that air is rushing back to your turbo and causing the compressor wheel to "surge". I'm willing to bet during shifts you hear a slight fluttering noise, thats compressor surge. Bad for the turbo
Apr 11, 2006, 07:15 AM
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For a second i thought maybe you were talking about a BOV on an intake with no turbo kit, but thats stupid haha, yes, so still, all of my above posts are still relevant
Last edited by Sicktght311; Apr 11, 2006 at 07:18 AM.
Apr 11, 2006, 07:41 AM
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i just took the car for a spin, and everything sounded the same as before. I hear no flutter sound, is there away to find out if i have compression surge?
Could the reason that I am not hearing the flutter be becouse I am only running like 5 PSI?
Could the reason that I am not hearing the flutter be becouse I am only running like 5 PSI?
Last edited by mitch44759; Apr 11, 2006 at 08:01 AM.
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Apr 11, 2006, 08:05 AM
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No matter what boost you are running i wouldnt really mess with Surge. My suggestion is just be better safe than sorry, either relocate the Air sensor to post BOV, or Vent the BOV back to the intake. You may not always hear the compressor surging, its just not good no matter what. Kills the life of the turbo
Apr 11, 2006, 09:31 AM
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wow, you guys think everyone is a noob or something. We didnt just throw a bunch of washers in the bov and go off boosting all over town. The spring rate was increased progressively till it opened at the right time. If anything its still a tad soft. That's better safe than sorry.
Assuming thats still vented and not recirced.
