Bov question

Discussion in 'Modifications And Maintenance' started by WrxMiller, Feb 27, 2009.

  1. WrxMiller
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    WrxMiller Well-Known Member

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    This question may have been asked before but I was tuned on a atmospheric bov and would like to switch it to a recirculating bov. Does this require a retune? Also id like to get some opinions on what bov to get. I was leaning toward the forged. thanks
     
    WrxMiller, Feb 27, 2009
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  2. Bullwinkle
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    Bullwinkle Well-Known Member

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    No retune needed. The action of a BPV or BOV is not tunable. The Subaru ECU expects a BPV (recirculating air), so your car will run less rich between shifts if you swap to a BPV.
     
    Bullwinkle, Feb 27, 2009
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  3. WrxMiller
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    WrxMiller Well-Known Member

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    good to know, thanks for the info
     
    WrxMiller, Feb 28, 2009
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  4. ej20
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    ej20 Well-Known Member

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    I use to run the atmosphere HKS and boy it gives me poping sounds from the exhaust. Took it off and car runs perfect, like 2yrs newer. Thats when I start not liking bov. So this time I"m going with a Recir Bov on my FMIC.
     
    ej20, Feb 28, 2009
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  5. WrxMiller
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    WrxMiller Well-Known Member

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    see i had the same thing. didnt mind the poping sound so much, but i feel like the car isnt as smooth
     
    WrxMiller, Feb 28, 2009
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  6. Shibbs
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    Shibbs The Daywalker

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    If the car is popping alot, its because the valve was not tuned properly. It needs to be stiffened up. When you're idling, my car for example pulls about 18-20 in hg. When decelerating in gear around 3k rpms it goes up/down to 24 sometimes closer to 25 in hg. This is when the valve would open, allowing un-metered air in, causing a lean condition, causing popping.

    Tighten the BOV a little and the popping should have gone away.
     
    Shibbs, Feb 28, 2009
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  7. Bullwinkle
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    Bullwinkle Well-Known Member

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    I don't know a ton about all the different BOV's, but the popping is due to unburt fuel igniting in your exhaust. This isn't a terrible problem if you don't have any cats, but if you have cats, this will blow them up quickly.

    As I mentioned above, Subaru ECU's expect the air from a shift to be blown back into the engine, so if you have a vent to atmosphere BOV, that air is missing so you have a rich period between shifts. This rich condition exists momentarily even with the stock BPV, but is much much more pronounced if you are running a fully atmospheric BOV.
     
    Bullwinkle, Feb 28, 2009
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  8. Paul Revere
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    Paul Revere BANNED

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    Nate can you explain why I got 10.8's AFR's with my Forge full recirculating bpv and the same night I tired a TurboXS full atmospheric bov and was getting 13.1's AFR's? I changed it right back to the Forge, I was just out to hear the difference.

    *Edit* Sorry the AFR's were at WOT and above 6200 rpm
     
    Paul Revere, Feb 28, 2009
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