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Thread: Fuel injector flow rate in $A1 for the 7730

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  1. #1
    Fuel Injected! woody80z28's Avatar
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    Fuel injector flow rate in $A1 for the 7730

    Call me crazy, but I've looked all over the XDFs for $A1 and can't find where to change the fuel injector lbhr.

    Long ago I bought my 3400 swap chip from a respected tuner and tweaked it from there. The chip was set up for the 22.5lb 3400 injectors, but the only flow rate I see is KDISFS which still shows the stock 3.1 value of 16.7lb. It never made sense to me, but it worked well so I didn't fuss over it.

    My new build with ported heads and street/strip cam pushes me past the 22s according to the masses. Not a problem, but where do I modify that in the BIN for my new 28s?

    Thanks for any help...
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1) sold! for crazy money...but I miss it
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D) gone but not forgotten
    96 Beretta "T56" - 4.8 LS RWD swap / 6spd (0411/2156)
    01 Silverado 2500HD - stock Vortec 8.1 / ZF6 6spd (0411/8322)
    https://www.youtube.com/c/GEARHEADdezign

  2. #2
    Super Moderator Six_Shooter's Avatar
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    IIRC the injector constant isn't used in $A1 and instead the BPC or BPW scaler or table is used.
    The man who says something is impossible, is usually interrupted by the man doing it.

  3. #3
    Fuel Injected!
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    I hope I'm not...open mouth insert foot...with that said, I'm not familiar with $A1 but I've messed around with $8D and in the scaler there is "injector flow rate." It also has "engine displacement." TP makes everything so easy. I remember crunching the math, converting to hex and changing the value at some #### address before!!!

  4. #4
    Fuel Injected!
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    For $A1, look in Scalars, Fuel, KDISFS in Lb/Hr

  5. #5
    Fuel Injected! woody80z28's Avatar
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    Looking more closely in the definition I see KDISFS is "for DIC/DIS calculations only." Makes sense since it is set incorrectly at the stock flow rate in my tune. If it's only for the DIC that doesn't exist in my car then who cares.

    I see a high and low "BPW threshold" in the ADX set at 1.28 and 0.98 mSec.(KAPLH and KAPLL) Do I just divide this by 22.5 and then multiply by 28? So 1.59 and 1.22 mSec? (I'm guessing that's for the the ~43 and ~55 pressures depending on the vacuum reference on the FPR?)

    $0D was so much easier with my truck... haha
    Last edited by woody80z28; 12-16-2017 at 01:44 AM.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1) sold! for crazy money...but I miss it
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D) gone but not forgotten
    96 Beretta "T56" - 4.8 LS RWD swap / 6spd (0411/2156)
    01 Silverado 2500HD - stock Vortec 8.1 / ZF6 6spd (0411/8322)
    https://www.youtube.com/c/GEARHEADdezign

  6. #6
    Super Moderator Six_Shooter's Avatar
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    The table you want is "Base Pulse Constant vs Desired % EGR" location $761.

    I don't know of a formula to set it. I just play with it until I get a good idle and then fine tune from there. I'm not usually using an EGR so I only usually need to modify the 0% EGR cell, if you are using EGR changing the rest by the same amount that you changed the 0% cell would likely keep you in good driveability and fueling.
    The man who says something is impossible, is usually interrupted by the man doing it.

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