lean code in aftermarket part - Page 2
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This is a discussion on lean code in aftermarket part within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Originally Posted by pwnster What are the cons of having a BOV? I bought the car with it already on, ...

  1. #16
    Registered User subypete's Avatar
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    Quote Originally Posted by pwnster View Post
    What are the cons of having a BOV? I bought the car with it already on, so I don't know much about them(nooby me).
    Here's some info on BPVs/BOVs: Blow Off Valve FAQ: Read if you are thinking of buying one! - NASIOC

    Here's an excerpt from the linked thread that answers your question:

    "Are there any negative effects with aftermarket BOVs? Yes. The downside of releasing the air to atmosphere is that it has already been metered by the mass air sensor, and when it blows off, the ECU will be injecting the wrong amount of fuel into the cylinders. The engine temporarily runs rich, meaning too much fuel is injected into the cylinders. On most tunes the target A/F under boost is @11.1:1 or so. Say you are at 11.1:1, then you shift and it vents. It will swing rich, typically to around 9.5:1. That is not that rich and this period lasts for under one second...again, nothing to write home about.

    This temporary rich condition isn’t usually that harmful. Technically, it can eventually foul spark plugs and even clog the catalytic converter as unburned fuel on the catalytic converter burns very hot, and too much of it can melt the cat. The odds of either of these two conditions actually happening is very, very low though, but that's the theory.

    As to blanket "you'll run rich" statements, a BOV will only run "rich" during hard acceleration and shifting as 99% of the time it stays closed."
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  3. #17
    Registered User Miggs's Avatar
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    Quote Originally Posted by pwnster View Post
    What are the cons of having a BOV? I bought the car with it already on, so I don't know much about them(nooby me).
    see if the bov has a manufacturer name or logo on it. all wrxs have bovs, or rather bpvs (by-pass valve). with a full re-circulatory bpv, it sends the air back into the intake. with many aftermarket bovs (blow off valve), the air is simple released into the atmosphere, which is counter-productive and can reduce performance. The main reason ppl like aftermarket bovs is for the signature pshhht! sound that they create after or during boost building.

    ---- BOV / Blow Off Valve Information ---

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    Quote Originally Posted by Miggs View Post
    +1 imo, it could at least aid the lean condition. You could also just have a sensor problem. Try cleaning your MAF.
    Got home from work, cleaned my MAF, we'll see how she handles tomorrow and if the light is still on. If it's still on, I'll get that code.

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    Quote Originally Posted by EJ257 View Post
    What was the DTC (P####)?
    I called the dealer this morning and the code they pulled was P0171

  6. #20
    Master Baiter EJ257's Avatar
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    Quote Originally Posted by pwnster
    I called the dealer this morning and the code they pulled was P0171
    You cleaned the MAF sensor, did the DTC go away? Has your front O2 sensor ever been replaced?
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    Quote Originally Posted by EJ257 View Post
    You cleaned the MAF sensor, did the DTC go away? Has your front O2 sensor ever been replaced?
    After being cleaned it did not go away. Not that I am aware of

  8. #22
    He simply abides. SD_GR's Avatar
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    PO171 can be caused by intake leaks (you have at least two of theses: the K&N is a leak, and the BOV is a leak in these terms...), an FPR reference problem, a dirty air filter, a dirty MAF, or the actual O2 sensor.

    Clean the air filter, the MAF again, the piping on the inside if the intake, check the FPR reference connection under the piping that goes to the passenger side, check all the connections including to the boost solenoid, check the wiring to the O2 sensor.
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    Quote Originally Posted by SD_GR View Post
    PO171 can be caused by intake leaks (you have at least two of theses: the K&N is a leak, and the BOV is a leak in these terms...), an FPR reference problem, a dirty air filter, a dirty MAF, or the actual O2 sensor.

    Clean the air filter, the MAF again, the piping on the inside if the intake, check the FPR reference connection under the piping that goes to the passenger side, check all the connections including to the boost solenoid, check the wiring to the O2 sensor.
    When I get some time, I will tackle these. Thanks for the help!

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    update: After i cleaned the MAF sensor, the next night the check engine light shut off, which it hasn't done in months. So 3 days later it's still off, I'm hoping it's fixed. I'll repost if it comes back on

  11. #25
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    The MAF sensor is a common immediate cause. The underlying cause is usually a filter problem, allowing the MAF sensor to get dirty in the first place. Either an aftermarket high-flow filter, or an opening in the stock filter box, or simply a dirty old air filter. Even stock cars do this. Modified intakes etc. I think make it more common and easier to recurr.
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    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

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