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Thread: Which tables for air/fuel

  1. #1

    Which tables for air/fuel

    Which table should I be editing when trying to adjust air/fuel? Let's say I dyno 13.5 and want to get to 13.0. Haven't dynoed yet, but just for conversation sake.

  2. #2
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    Re: Which tables for air/fuel

    I like to keep PE at one value across the table, then I adjust the rest VIA IFR. Makes all my graphs flat as a board.

    Rick

  3. #3

    Re: Which tables for air/fuel

    Quote Originally Posted by Synergy
    I like to keep PE at one value across the table, then I adjust the rest VIA IFR. Makes all my graphs flat as a board.

    Rick
    So your PE base values are all the same? What do you have them at?

    And then you use the injector flow rate to get the air/fuel ratio you want. Do you happen to know how the flow rate affects the air/fuel. I just wanted to know how much to vary it by so I don't grossly overdue it. Thanks.

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    Re: Which tables for air/fuel

    For whats its worth:

    SET NEW FUEL INJ DATA: Measure resistance at the poll. A stock LS6 for example is 17ohms. Noting 0 adj at 18v, the amperage is
    18v = 17ohm * amp
    amp ~= 1.05 or so.

    New Fuel Inj, for example Lucas 30lb/hr = 16.4ohm resistance. Zero adjust for amp flow at
    16.4ohm and 1.05mps = 17.36v at no adjustment.
    Multiply the entire inj volt offset table by
    17.36/18. This is the base setting for the injector.

    if 14.682/PEvalue = 13.5(a/f programmed) and your wideband A/F=13.5 (wideband), your IFRs are correct.
    several scenerios:

    SET IDLE FUEL: decrease or increase IFRS until ~0.8% STFT idle.

    SET WOT:
    //air fuel is leaner than expected
    if (wideband > programmed a/f)
    decrease IFRs scaling through 0% change at idle
    45kpa??

    //air fuel req richer than expected
    if (wideband < programmed a/f)
    increase IFRS scaling through 0% at idle.

    You must scale this evenly through idle to maintain the idle mixture and maintain good low end snap.


    //desired tuning achieved when
    wideband = programmed a/f.
    At this point, you can use the PE table to go richer or
    leaner.


    ADJUST PART THROTTLE USE THE PE TABLE:
    I use the o2 voltages, histogram and wideband for this.

    NOTE: At idle, expect around 40-45kpa, this value is close to the center of the IFR table. Therefore, adj seen will be a result of data left of this cell.

  5. #5

    Re: Which tables for air/fuel

    You are too smart for me. That just went over my head.

  6. #6
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    Re: Which tables for air/fuel

    :huh2: Agreed. I love mathematics... My table stock came with a scale in it. small to large over the course. The graph shows it to be flat. When I had mine professionally tuned, they used the same scale and multiplied it by .75

    Don't know... just being observant.
    Because it must be Brent!&&\'05 FORD F-250 Diesel, baby

  7. #7
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    Re: Which tables for air/fuel

    :huh2: I didn't think it was that bad. Let me simplify:

    Increase the flow rates by 1%, expect a 1% lean condition
    Decrease the flow rates by 1%, expect a 1% rich condition.


  8. #8

    Re: Which tables for air/fuel

    Gotcha! 8)

  9. #9
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    Re: Which tables for air/fuel

    I don't understand how decreasing the flow rate of the injectors cause a rich condition and increasing causes a lean condition. Isn't that backwards?
    Eric - 01 Silverado 5.3 ECSB
    ET: [email protected] 1.77 60' 5200 lbs

    Crappy website about my truck

    My Myspace page
    Usually contains explicit material (language, etc..)
    It's Peanut Butter Jelly Time!

  10. #10
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    Re: Which tables for air/fuel

    If you DECREASE the flow rate of the injectors, the car's computer thinks it has smaller injectors installed and will
    command a larger pulsewidth. A good example:

    given lb/hr x 454/3600 = gm/sec

    stock ls6 28lb/hr : 3.53gm/sec
    lucas 30lb/hr inj : 3.78gm/sec

    If you install the lucas injector without any changes to tuning, you will get 3.78gm/sec fuel flow, but the car's computer is doing calcs based on 3.53gm/sec. This will
    cause an enrichment 30/28.





  11. #11
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    Re: Which tables for air/fuel

    Ahh, thanks for the clarification.
    Eric - 01 Silverado 5.3 ECSB
    ET: [email protected] 1.77 60' 5200 lbs

    Crappy website about my truck

    My Myspace page
    Usually contains explicit material (language, etc..)
    It's Peanut Butter Jelly Time!