venting your bov to the atmosphere

Posted by dsm92talonboost, Aug 14, 2011

Please Support Magnus Motorsports
  1. dsm92talonboost

    dsm92talonboost Proven Member

    Joined Dec 15, 2009
    sacramento, California
    I know their are some post on this but not getting to much info on it. I just curious exactly what is venting your bov?? and why might it cause you to run rich? My bov is not recirulated.. does that mean its vented to the atmosphere? i have a problem with running lean, think that may be a problem? Im just all confused on this venting thing and what it is!

    Log in/Register to remove ads
  2. Boostinsideways

    Boostinsideways Banned Member

    Joined Feb 4, 2011
    Arab, Alabama
    Having your blowoff valve non recirculated is venting to atmosphere. Instead of going back into your intake system after the Mass airflow senor it just escapes.

    The mass air flow sensor measures the volume of air pulled through it, and uses that to calculate the amount of fuel that is required. If you let air escape you will run rich.
  3. Bud92gsx

    Bud92gsx Supporting Member

    Joined Jan 16, 2008
    Your moms house, BC, Canada
    My DSM:
    1992 Mitsubishi Eclipse GSX

    13.300 @ 102.400 MPH
  4. keithlag

    keithlag Proven Member

    Joined Aug 24, 2010
    Durrington, Europe
    yes you are venting to atmosphere it will mess up your fueling as the ecu will make up for the lost air with fuel
    My DSM:
    1996 Mitsubishi Eclipse GST

    Street Build

    16g   manual
  5. project98dsm

    project98dsm Proven Member

    Joined Feb 25, 2006
    Pineville, Louisiana
    I understand that I'm not a mod on this website, and that it's not my job or responsibility to point things like this out. I also understand this is a newbie area. But can you honestly say that you have searched on what venting a bov is/does? There are more threads than I can count on one hand as to what this is/problems that will arise/will it give me a cool "whoosh" sound etc. Just making a point. It's recommended to actually search before asking something that has been answered more times than NOT answered. Please don't come on here and just post something random thinking you'll get a quick response, when just typing in "venting bov" and clicking search will probably reap you better responses. Please don't think I'm flaming you or being a douche, I'm just making a point.
    My DSM:
  6. agentorange313

    agentorange313 Supporting VIP

    Joined Dec 21, 2008
    Westfield, New Jersey
    Our vehicles are equipped with a MAS system. These sensor units read the air that passed thought them by heating up a "hot wire" or similar to a toasters internal heaters. Air then travels over the hot wire. The wire's electrical resistance increases as the wire's temperature increases, which limits electrical current flowing through the circuit. This is how the ecu calculates how much air is entering the system.

    Our MAS systems are before the turbo, so the air is metered entering the system. This means that the ECU calculated the air before the turbo, if you are release air after this sensor the ecu can not properly calculate how much air is n the system. It is considered to be un-metered air. That is why boost leak tests are so important, un-calcualted air enter or existing the system can mess up your fuel to air ratio.

    If you want to vent, vent properly. Utilize another system of calculating air, whether it be a GM blow through style MAF or Speed density (map sensor and air inlet temp). These two systems calculate air that is in the system rather than before/entering.

    I dont think you searched hard enough:


    edit: nice link Bud, great minds think alike
    Last edited by a moderator: Jun 5, 2014
    My DSM:
    1991 Eagle Talon TSi AWD

    10.455 @ 104.000 MPH
  7. hollywood_ikr

    hollywood_ikr Proven Member

    Joined Jan 17, 2006
    el paso, Texas
    In my experience venting to the atmosphere on a stock MAS might make your car run a little weird at idle and possibly cause your car to die after a high rpm shift, nothing worse than that. Sounds to me like your real problem lies elsewhere, but it won't hurt to recirculate the air properly.
    My DSM:
    1998 Mitsubishi Eclipse GSX

    Street Build

    GT40   manual
    Caleb4G63 likes this.
  8. dsm92talonboost

    dsm92talonboost Proven Member

    Joined Dec 15, 2009
    sacramento, California
    thank you for all the help, and yes i should of searched harder but i just wanted some more direct info on exactly what it is which you guys told me.
  9. SrKegler

    SrKegler Proven Member

    Joined Feb 29, 2004
    Daytona Beach, Florida
    However, that won't solve your running lean problem. How did you determine that you were running lean.
  10. 400hp93talon

    400hp93talon Proven Member

    Joined Aug 11, 2009
    Fort Madison, Iowa
    I think the big problem is when people run the bov without the recirculating tube on they don't plug the hole in the intake pipe that is after the maf sensor so thats what causes the AFR to act funky. If you plug the hole and don't use the recirculating tube you shouldn't have any issues with it.... I never have anyways. And lets face it I might sound a little childish here but everybody loves turbo cars that have awesome sounding bov's unless you live in California or somewhere else you need to keep it on the hush hush. Again that's just me.
    My DSM:
  11. jtmcinder

    jtmcinder DSM Wiseman

    Joined Nov 4, 2003
    Iowa City, Iowa
    If they do that, then they deserve to take a bus. :)

    My guess is that people are venting 2G with a stock CPV. The only good thing to say about this is that they probably have very clear cylinder wall, washed clean by the extra fuel.
  12. Tfitch90

    Tfitch90 Proven Member

    Joined Jun 26, 2011
    Bowie, Maryland
    Since we on the subjects of BOV's. Is the one that comes free with the PR FMIC acceptable ? I must admit i like the "PSSHHH" sound. Im sure it will make my girl wet hahaha it sure does somethin for me.
  13. DSMunknown

    DSMunknown Proven Member

    Joined Sep 16, 2004
    Worcester, Massachusetts
    Die. Die. Die. Kill. Kill. Kill.
  14. snowborder714

    snowborder714 Moderator

    Joined Oct 15, 2006
    Mechanicsburg, Pennsylvania
    All of the links posted above will help you with your question.
    My DSM:
    1995 Mitsubishi Eclipse GST

    12.529 @ 110.820 MPH

Share This Page


Log in/Register to remove ads

Support Vendors who Support the DSM Community
Ace Race Parts Advanced Fuel Injection Archer Fabrication Boostin Performance ECM Tuning Extreme Turbo Systems ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions Jackson Auto Machine JNZ Tuning Magnus Motorsports Miller Import Parts Morrison Fabrication & Design OHM Racing Race Components Inc RockAuto RoadSurge Spultronix Performance STM Tuned Strictly Import Motorsports VR Speed Factory