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Thread: Way Lean,when just Touch throttle

  1. #1
    Potential Tuner
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    Way Lean,when just Touch throttle

    Can not figure this out i have a 421 stroker 650 lift cam trick flow heads 12 to 1 with mast intake 4500 bore and accu fab tb and have an issue with the speed density tune...at start and for 5min or so when u go to give it gas as soon as u touch the pedal it goes past 18.0 lean and trys to stall,let off, it idles.give it gas does again...this is with it rich at idle cause if I run idle leaner its worse, once running for a bit it stops doing this... dont change much when cold but its worse when hot...so if I add fuel then after it stops this issue it like 10s rich just off idle...its like I need a squart of fuel just as u touch the pedel what should I do?

  2. #2
    Post your tune.
    1968 Bel Air Wagon
    L92/6L80E

  3. #3
    Senior Tuner Lakegoat's Avatar
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    Jul 2012
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    Florida
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    I will guess. If you have an adjustable FPR with a pressure gauge, in park or neutral, just tap the gas and watch the needle. If it drops below your target pressure, that will cause a lean spike. Adjust the pressure up until this does not happen and then go back and adjust your fuel trims.
    Again, happened to me--I don't know your setup. Hope this helps.

  4. #4
    Senior Tuner mowton's Avatar
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    By the way the number 1 rule on the forum is if you are looking for help....post your tune and logs of the event....makes it tough, we are just guessing.

    Rant being said :-) Are you running open loop or closed loop? If closed loop the initial cold start is running off the open loop airflow table..... might be lean. If running open loop, some tuners set the whole table to 1.0. Should put back the -40 to like 133 degree stock value sand blend that into the 176 degree which would be the start of the 1.0 (stoich).

    Ed M
    Last edited by mowton; 08-09-2015 at 09:41 AM.
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

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  5. #5
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    How do i post my tune? and im running open loop

  6. #6
    Potential Tuner
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    None adjustable fpr running twin 255 pumps

  7. #7
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    Bump?