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This is a discussion on afr question within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; Hello, just a quick question on afr. On normal shifting why does afr dip briefly rich ( 11.6) or so ...

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    afr question

    Hello, just a quick question on afr. On normal shifting why does afr dip briefly rich ( 11.6) or so between shifts? Thank you.

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    Master Baiter EJ257's Avatar
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    It should go lean between shifts, since when your foot is off the gas, the injectors shut off.
    2005 WRX STi (Mods | Virtual Dyno)

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    Registered User nsibanez's Avatar
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    Ever notice how if you're boosting though, in between shifts your rpm gauge raises even though your foot isn't on the gas?

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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by nsibanez View Post
    Ever notice how if you're boosting though, in between shifts your rpm gauge raises even though your foot isn't on the gas?
    Yeah - a bit annoying at first but it ends up helping keep the revs up. I believe it is for emissions purposes.

    I'm honestly not sure if that results in a rich spot.

    A vent to atmosphere BPV will for sure though.
    "From a little spark may burst a mighty flame." - Dante
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    Registered User nsibanez's Avatar
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    Quote Originally Posted by mycologist View Post

    A vent to atmosphere BPV will for sure though.
    Same thing as a BOV?

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    That's kind of what I was thinking when the rpm jumping a tad at the shift. The afr dips only for a split second and then goes to where it should be. Just wondering why if anyone knows.

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    Moderator Donkey's Avatar
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    It would probably help if you listed car/year and mods..........
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    11 wrx, cai, tbe, ebcs, TP stage 2 custom tune.

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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by nsibanez View Post
    Same thing as a BOV?
    Yup.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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    Quote Originally Posted by mycologist View Post
    Yeah - a bit annoying at first but it ends up helping keep the revs up. I believe it is for emissions purposes.

    I'm honestly not sure if that results in a rich spot.

    A vent to atmosphere BPV will for sure though.
    its called shift flare, its not because of emissions. I have noticed it is worst if you are running extremely rich and happens a lot more in the low to mid rpms.

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    Registered User nsibanez's Avatar
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    Quote Originally Posted by mycologist View Post
    Yup.
    Noticed a good 1-2 mpg average drop with it, so I took it off.
    Plus in 4th, letting off the gas at around 2500-3000 rpm range I always heard a high pitched squeek. Figured that could have been the problem, haven't noticed it since I took it off either....turbo flutter by chance?

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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by nsibanez View Post
    Noticed a good 1-2 mpg average drop with it, so I took it off.
    Plus in 4th, letting off the gas at around 2500-3000 rpm range I always heard a high pitched squeek. Figured that could have been the problem, haven't noticed it since I took it off either....turbo flutter by chance?
    Yeah, if it wasn't blowing off enough it would surge the compressor for sure.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

  14. #13
    Registered User nsibanez's Avatar
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    Quote Originally Posted by mycologist View Post
    Yeah, if it wasn't blowing off enough it would surge the compressor for sure.
    I don't think it's anything serious. I guess they're adjustable, but I don;t know how to do that...so I think I'm going to sell it soon. Nothing wring with it...bought it off a coworker with an 11, and only was used for about 2000 miles. Same with me. I just removed it to troubleshoot the noies, and just don't care about putting it back on.

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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by nsibanez View Post
    I don't think it's anything serious. I guess they're adjustable, but I don;t know how to do that...so I think I'm going to sell it soon. Nothing wring with it...bought it off a coworker with an 11, and only was used for about 2000 miles. Same with me. I just removed it to troubleshoot the noies, and just don't care about putting it back on.

    Yeah a recirculating one that is adjusted correctly is the only way to go if you aren't happy with stock. I never messed with mine but have heard the newer models are a bit weak if you are going much beyond stage II.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by nsibanez
    I don't think it's anything serious. I guess they're adjustable, but I don;t know how to do that...so I think I'm going to sell it soon. Nothing wring with it...bought it off a coworker with an 11, and only was used for about 2000 miles. Same with me. I just removed it to troubleshoot the noies, and just don't care about putting it back on.
    What valve?
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