Crazy vacuum leak. Help appreciated
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This is a discussion on Crazy vacuum leak. Help appreciated within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I tried meticulously to sort this out thru research and fiddling on the car but i just need help. I ...

  1. #1
    Registered User WyomingWagon's Avatar
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    Crazy vacuum leak. Help appreciated

    I tried meticulously to sort this out thru research and fiddling on the car but i just need help.

    I bought an 02 wrx about 6 months ago as a project. (not knowing much at all about subarus)
    Car has
    -565cc DW injectors
    -intake
    -tbe
    -silicone tubro inlet
    -fmic
    -bov
    -uncatted up pipe
    car has 125k, was giving off codes for maf(found MAF unplugged) and front 02 so i replaced both, but the car still idles funny with MAF plugged in. now monitoring a/f ratios on my AP i notice 25% correction.. showing -8 psi vacuum at idle, when i revv and release throttle it nearly stalls finding idle again(this gets worse when engine is warm). Runs great other than the weird idle. Holds boost well. no codes anymore.. i believe i may have a vacuum leak but can't find it. going to build a tester when i have time and clean iacv. any input would be appreciated.. this car has a lot of potential and is my first subaru, please help

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    Moderator Donkey's Avatar
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    25% correction means the fuel trims are maxed out. Is it positive or negative correction? What intake is on the car?
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    Registered User WyomingWagon's Avatar
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    i can't tell the brand.. looks about the same diameters as spt or cobb.
    just odd that it ran better with MAF unplugged before i started replacing sensors.
    or maybe it was running lean the entire time
    i will post a pic of the intake as soon as i can thank you for the reply

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    Registered User WyomingWagon's Avatar
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    Click image for larger version. 

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    this is my intake

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    Registered User WyomingWagon's Avatar
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    Click image for larger version. 

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    Registered User WyomingWagon's Avatar
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    i did some digging around and found a black tube not connected to anything but cannot for the life of my figure out where it goes. in the picture(sideways picture) the tube is connected to this black sensor.. with silver clamp on it.. i found this hose on the driver side behind the manifold..... anyone have an idea what it is or where it could go?
    i have a feeling this could contribute to the issue

  8. #7
    Registered User WyomingWagon's Avatar
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    Quote Originally Posted by Donkey View Post
    25% correction means the fuel trims are maxed out. Is it positive or negative correction? What intake is on the car?
    any idea what intake?
    i don't see any brand stamping or anything

  9. #8
    Moderator Donkey's Avatar
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    Need to know if the correction is positive or negative. Looks like an old TurboXS one but who knows. Measure the inner diameter.
    Resident Adviser @ WTF Tuning, LLC
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  10. #9
    Registered User WyomingWagon's Avatar
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    ok i will measure it. at idle it finds and stay at about 25% positive correction. when applying throttle it jumps down towards normal numbers. I've seen it go negative 25% as well..if i get a chance i will post logs or a video of the behavior

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    Registered User WyomingWagon's Avatar
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    and i found out that hose from the TGV goes no where. lol

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    Registered User WyomingWagon's Avatar
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    is it possible that installing the FMIC without any tuning would cause this odd AFR?

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    OMG WTF MainFrame's Avatar
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    Quote Originally Posted by WyomingWagon View Post
    is it possible that installing the FMIC without any tuning would cause this odd AFR?

    It would throw things off.. but not near as bad as installing the injectors, or intake without a tune. All of those mods require a custom tune to run right.. and the BOV, well it just won't run right regardless of the tune.. unless you switch to speed density or blow through, and you're far from needing that.

  14. #13
    Registered User WyomingWagon's Avatar
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    well i was informed that it has been tuned for everything except the fmic (possibly bov)
    i have suspicion that the guy before ran a bigger turbo and maybe replaced it with the td04 then pulled MAF to make it run stock ratios in limp mode to sell it (all without tuning or tweaking)
    does this sound crazy? is it possible? i know he ran a blouch 16g at one point...

  15. #14
    OMG WTF MainFrame's Avatar
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    Yeah, people lie about their cars to sell them for more all the time. Entirely possible.

  16. #15
    Registered User WyomingWagon's Avatar
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    would doing so cause said symptoms?
    The near stall after releasing of throttle (once engine is warm)
    extreme low and high air fuel correction rates -/+ 25%
    car drives fine pulls hard and hits full boost which is set to 16psi or so.
    Or do i just have a leak i can't find?
    Maybe just needs a tune really bad?

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