high pitch flutter under boost

Discussion in 'Technical' started by gezky, Jun 25, 2007.

  1. gezky

    gezky New Member

    when i jumped in my z this morn, she started makeing a real strange noise when it came on boost. it's kind of like a high pitch fluttering, at first i thought turbo, but wouldn't that make a much more nasty noise aswell as piss out the smoke? i can rev it up stationary without making the noise, it'll only happen when it loads up. i thought it may even be small blow in an intake gasket. would that make this weird ass noise???
    an ideas??
     
  2. sandeep

    sandeep Active Member

    Is it when you lift off the throttle under load at high boost?
     
  3. scump

    scump John Dorian

    hey mate give us some more details... does it only come on high boost.. is it more like a booming sound, etc.

    if it comes on high boost 4500+ and is more like a booming sound, and u can feel a definate power loss when u hear it... have a look at your blow off valves, might be loose.
     
  4. AndyMac

    AndyMac Better than you

    It could possibly be your bov's or recirc springs are worn and letting boost past.

    Either that or detonation...more like a metallic ping noise tho.

    Could again be your turbo bearings have excessive play, again this is new turbo arena.

     
  5. gezky

    gezky New Member

    it's only when i'm loading it, goin heavier on the throttle. i can make it happen at any rev range. if i keep an eye on my boost gauge and keep it under about 4 psi you never hear it. i can free rev it to 5000 without hearing it, but up a hill in 2nd when you try to spool up it comes on loud. the noise is hard to explain. if i bring the throttle on slowly, as it comes on boost the noise starts out as a lower pitch flutter, but still fairly loud as the throttle is pressed more the noise freq. of the flutter seems to match the engine rpm. but becomes a much higher pitch, almost like belt squeal.
     
  6. topher

    topher Banned

    sounds like detonation to me... but then i aint an expert...although loading it up in 2nd gear in low revs climbing a hill cant be too good anyway
     
  7. ZWEETT

    ZWEETT Active Member

    well i

    had such a noise b for, and it turns out it was the recirc valves.

    removed. noise gone.
     
  8. frysie

    frysie FRYTECH

    Gotta love necro-thread digging.

    Seems like I have this issue. I shuld be fine picking these up in the states?

    Making a similar noise only on heavy loading > 10+ psi.
     
  9. ZWEETT

    ZWEETT Active Member

    Just remove them and plug the holes, unless your wanting to keep every thing as factory.

    Good work on the search find :D

     
  10. MickW

    MickW Carntry member...

    Gold medal necro frysie :D

    Stock recirculation valves are still available, I have a set on the way from CZP right now.

    Mate, have you done a boost leak test? Crook recirc valves won't show up as leaking because they vent back into
    the intake tract but I'm wondering if you're hearing a split hose maybe?
    Also, if the recirc valves are rooted you'll be hearing the goose honk noise when you lift off the throttle, it's
    fairly hard to miss.
     

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