backfire while downshifting: is it bad for turbo

  1. yyalb

    yyalb Member

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    My SI is running ktuner stock/23psi tune. When I drive it aggressively and heel toe downshift, I can hear a very loud pop from the exhaust after I blip the throttle. It sounds cool, but I am worrying whether that's harmful to the turbo.

    I guess the reason for that is a combination of rich mixture and fresh air sucked from exhaust pipe when close the throttle suddenly.
     
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  2. Urabus99

    Urabus99 Senior Member

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    I get that popping sound from having a catless downpipe
     
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  3. Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    Not sure if KTuner included "Crackles & Pops" with that tune; but, what you are hearing is EXCESS fuel igniting downstream and out your exhaust. It is WELL past the turbo and does not have an effect on that component.
     
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  4. Jman

    Jman Member

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    That sounds just like a good downshift
     
  5. hobby-man

    hobby-man Senior Member

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    Depending where it is igniting couldn't that be torching the cat?
     
  6. Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    Not necessarily.
    On a Completely stock set-up, the crackle/pop may occur shortly after the mid pipe.
    On a car
    With high flowing cats or catless pipes, the crackle/pop would happen toward the end of the exhaust.

    Just depends on the velocity of the exhaust flow.
    Make sense to you???
     
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  7. typeaarrr

    typeaarrr Senior Member

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    I be more concern about why your car is running too rich to be causing the popping noise.

    A too rich condition can clogged or fouled up engine components, crappy gas mileages, and poor engine performance.
     
  8. OP
    yyalb

    yyalb Member

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    It's only happening when I do a downshift and blip throttle at neutral say from 3500 to 5000. I need to give it quite large throttle input to wind it up because of the heavy flywheel. I guess the map is not accurate enough at that scenario. Normally the ktuner tune looks just fine.
     
  9. Micah

    Micah Senior Member

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    Point to be made here. Backfire is dangerous and not likely what you are hearing. Afterfire is likely what you are interpreting as the pop.

    Backfire means ignition going back where it doesnt belong, ala the intake path of the cylinder(exception for Miller cycle engines).
     
  10. Design

    Design Senior Member

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    On the MS3 we'd occasionally get the exhaust pop when shifting at WOT. You have to remember that fuel targets are a bit richer under load. And the sudden change can send a small amount of unburnt fuel downstream.

    As the Mazda engineers would say, a single pop would be fine. Multiple pops... maybe not so much.

    And if you're really concerned about it, run a datalog and share with the community. :cool:
     
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  11. MutatedMango

    MutatedMango Senior Member

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    How much does that cost?
     
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