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Lean everywhere except under boost...

Discussion in 'EFI Tuning Questions and Engine Management' started by sniperd, Feb 16, 2010.

  1. sniperd

    Joined:
    Dec 7, 2009
    I have a 89 5.0, T70 turbo, PMAS pro tube calibrated for my 42# injectors. regulator set at 40psi fuel pressure. Stock ECU.

    I am lean everywhere except under boost, cruising around im at 16.8 - 17.4 AFR's, under boost im at 11.8-12.4.

    What gives? why would I be so lean everywhere except under boost? It seems like If i disconnect my IAC or set the idle lower it will help previously, but with idle at 1,000 rpm to keep the MAF from registering low voltage I cant get the AFR's good.
     
    sniperd, Feb 16, 2010
    #1

  2. BottleFed70

    Joined:
    Sep 7, 2006
    Sounds like it needs a tune.
     
    BottleFed70, Feb 16, 2010
    #2

  3. sniperd

    Joined:
    Dec 7, 2009
    People are running just locked timing and modified fuel pressure and having good results. you don't need a tune.
     
    sniperd, Feb 17, 2010
    #3

  4. Matt Cramer

    Joined:
    Sep 29, 2006
    For certain values of good results - locked timing isn't going to give the same level of drivability as a custom advance curve, and you're already mentioning issues like the ECU spitting out error messages if you try to idle at normal speed.

    I'd suspect something is wrong with your MAF calibration.
     
    Matt Cramer, Feb 17, 2010
    #4
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