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boost sputter @ high boost

Discussion in 'Forced Induction' started by b16stalyun, Jan 3, 2009.

  1. b16stalyun

    b16stalyun New Member

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    question, 2nd gear im at 13 lbs with creep up to 15. 3,4,5 gear i get a heavy sputter when i hit full boost. it does not do it in 2nd gear. only 3rd+ when i hit full boost. i thought i was hitting boost cut because of the boost creep. my boost cut is at 22.9lbs. I have a Motorola 2.5bar map sensor. which should be good to 35lbs. (1bar=14lbs) if im correct. so i lowered the boost in 3rd+ to 16.5lbs with a creep to about 19/20lbs depending on temp. it is still breaking up and not going near 22.9lbs.

    what could be the problem? the weather is about 20degrees-40degrees outside.
    plugs?
    wires?
    weather?
    tune?
     
    Last edited: Jan 3, 2009
  2. austin20110

    austin20110 New Member

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    fuel
     
  3. Briansol

    Briansol Admins Admin VIP

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    keep in mind, at sea level, you're already AT one bar for the atmosphere... so, a 2.5 bar sensor gives you ~ 1.5 bar of boost to play with, or about 22psi.

    but, breaking up sounds like you need more fuel and a better tune to compensate for the different burn of fuel in winter vs summer.
     
  4. 99sidude

    99sidude Moderator Moderator VIP

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    Agreed. My car runs like ass when it gets really cold out. I had to richen it up a little to compensate for it.
     
  5. b16stalyun

    b16stalyun New Member

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    update. i ran my car today. it was 65 degrees outside still had the sputter.

    in 2nd gear my a/f is about 11.5~
    in 3rd,4th at times it goes down to 10's
     
  6. Briansol

    Briansol Admins Admin VIP

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    10s is way to rich. lean it out a little
     
  7. b16stalyun

    b16stalyun New Member

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    update. the boost sputter was due to spark plugs. changed em out, re-gaped em and they work fine
     
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