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Thread: Boost leak?

  1. #1
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    Default Boost leak?

    iv just completed my engine swap and now whenever the the turbo goes to spool up it bogs down and doesnt produce any power, iv looked for boost leaks couldnt find anything. i also read that at idle you sould have a vaccum of 20 psi and mines only around 13. Iv shimmed the wastegate and when it spools up it reads about 10 psi, is there a way the wastgate could be stuck open? im completely lost and would sure appreciate help. thanks in advance
    Jason

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    Default Re: Boost leak?

    did you check timing, just a thought
    2004 WRB STi

  3. #3
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    Default Re: Boost leak?

    vaccum isn't read in psi, and not all cars will read that much. it depends on condition of your engine and desity of air. i acually have never seen a supra pull 20 in.hg of vaccum at idle.

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    Default Re: Boost leak?

    come to my house i'll show ya one

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    Default Re: Boost leak?

    being right at sea level probably makes a difference, but if you didn't live so damn far away i would take you up on that. always wanted to see florida.
    "Failure is the opportunity to begin again more intelligently."- Henry Ford

  6. #6
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    Default Re: Boost leak?

    Quote Originally Posted by antman
    i acually have never seen a supra pull 20 in.hg of vaccum at idle.
    All of mine have, unless there was an intake manifold leak or damaged rings/valves.

    As a matter of fact a vac gauge is one hell of a diagnostic tool that many people overlook.

    Here are some of the things a vac gauge can tell you:
    • gauge reading steady 17-22 in Hg indicates normal engine in good condition.
    • gauge reading low but steady indicates late ignition or valve timing, low compression, stuck throttle valve, leaking manifold gasket, etc..
    • gauge reading steady but dropping regularly indicates burnt valve or improper valve clearance.
    • gauge reading dropping gradually at idle indicates obstructed exhaust.
    • gauge reading slowly dropping to zero as engine speeds up indicates obtructed exhaust.
    • gauge reading fluctuating between 15 and 20 in Hg at idle indicates stuck valve or ignition miss.
    • gauge reading drifting indicates a minor intake leak at the manifold.
    • gauge reading fluctuating as engine speed increases indicates weak valve springs, worn valve stem guides.
    • gauge reading vibrating excessively at idle but steady as engine speeds up indicates worn valve guides.
    • gauge reading vibrating excessively at all speeds (when not under boost) indicates a blown head gasket.
    • healthy decelerating engine reading should jump to 21 thru 27 in Hg as open throttle released.

    These rules hold true for just about all 4 stroke gasoline engines, regardless of manufacturer or configuration (I4, I6, V6, V8, etc..)
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  7. #7
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    Default Re: Boost leak?

    wow thats some damn good info!!!!!

    and yea florida is nice until the summer. i have no A/C in my car cause the line blew and im busy buying performance shit rather than 50-80 bucks for a hose. LOL if you dont have A/C in florida yur a dumbass so i am a dumbass

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    Default Re: Boost leak?

    Quote Originally Posted by Supracentral
    All of mine have, unless there was an intake manifold leak or damaged rings/valves.

    As a matter of fact a vac gauge is one hell of a diagnostic tool that many people overlook.

    Here are some of the things a vac gauge can tell you:
    • gauge reading steady 17-22 in Hg indicates normal engine in good condition.
    • gauge reading low but steady indicates late ignition or valve timing, low compression, stuck throttle valve, leaking manifold gasket, etc..
    • gauge reading steady but dropping regularly indicates burnt valve or improper valve clearance.
    • gauge reading dropping gradually at idle indicates obstructed exhaust.
    • gauge reading slowly dropping to zero as engine speeds up indicates obtructed exhaust.
    • gauge reading fluctuating between 15 and 20 in Hg at idle indicates stuck valve or ignition miss.
    • gauge reading drifting indicates a minor intake leak at the manifold.
    • gauge reading fluctuating as engine speed increases indicates weak valve springs, worn valve stem guides.
    • gauge reading vibrating excessively at idle but steady as engine speeds up indicates worn valve guides.
    • gauge reading vibrating excessively at all speeds (when not under boost) indicates a blown head gasket.
    • healthy decelerating engine reading should jump to 21 thru 27 in Hg as open throttle released.

    These rules hold true for just about all 4 stroke gasoline engines, regardless of manufacturer or configuration (I4, I6, V6, V8, etc..)

    that should be a sticky cause that is some of the greatest info i've seen in a while....never ceases to amaze me

  9. #9
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    Default Re: Boost leak?

    yes stickie this definatly ^^^^^

  10. #10
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    Default Re: Boost leak?

    Quote Originally Posted by Seven M
    come to my house i'll show ya one
    Ditto!

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