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Thread: WOO HOO...got the programmer, not so happy results of ACHT bin findings....

  1. #1
    Fuel Injected!
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    WOO HOO...got the programmer, not so happy results of ACHT bin findings....

    Got my eprom programmer today and did not think to get an eraser......

    Ripped the ACHT bin I am running and found that the "Initial Advance" is 10 degrees.

    I was kind of hoping that it would be 0 degrees because that would have explained the seemingly large amount of pinging during the 3-4 gear area of acceleration when I had the distributor timing at 10 degrees.

    I backed the timing down to 6 degrees and still have very light pinging in that area and now am not sure why since I now know what the Initial Advance is set to in the eprom.

    hmmmmmmm....

    What to do next?

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    Well you have a ACHT chip for a 2.8L engine in a 3.4L engine... so maybe look for a 3.4L bin and see how far off the timing is?

    3.4L came with 16149396 ECM
    http://www.gearhead-efi.com/Fuel-Inj...Information-DF

    Change injector size, change engine displacement and start to tune it.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  3. #3
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    Using the $4e.xdf, it appears that the constant I have to tweak is the "BPW constant for EGR off" parameter. I've set the minimum temp for egr to "FF" in the table and have set the EGR failure bit to 0.

    I did find this thread and based on the formula in that thread, as well as another thread I found from a different board:

    BPC=1461.5*(.567/5.796 gm/sec) -- where .567 is the cylinder size of one cylinder in the 3.4l engine and 5.796 grams per second is the flow rate of the 4.3l injectors I am using. The resulting value is based on 13psi fuel pressure I believe.

    My math shows 142.97
    Last edited by damanx; 03-29-2013 at 05:19 PM.

  4. #4
    EFI GearHead ! EagleMark's Avatar
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    Well close but I think you calculated cylinder liter based off 8 cylinders? For 6 cylinders I get 0.4186930249/5.669904625 = BPC 143.899



    TBI
    Val = 1461.5 * (VOL/RATE)
    VOL = Vol of 1 Cylinder in liters,
    RATE = Injector flow in gms/sec

    Did you use the calculator I made?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  5. #5
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    I don't have any software currently to run that.

    Currently installing openoffice......

    If I did it correctly, that is showing the new BPC at

    138.1397605227

    In that spread sheet, it appears the engine size is not matching up.
    Last edited by damanx; 03-29-2013 at 06:21 PM.

  6. #6
    EFI GearHead ! EagleMark's Avatar
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    It's Open Office and FREE! Does everything Microsoft Office does... including opens all MS Office files... Oh and it will save in MS Office format... I think MS Office is out of business...

    Wow three times the file size for all the MS encryption not needed...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  7. #7
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by damanx View Post
    I don't have any software currently to run that.

    Currently installing openoffice......

    If I did it correctly, that is showing the new BPC at

    138.1397605227

    In that spread sheet, it appears the engine size is not matching up.
    Have to have correct Bore and Stroke for it to be accurate, I just entered one for one of the 3.4L engines...

    There is also a Old fuel pressure table and New Fuel Pressure table

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  8. #8
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    Hmmmmm....don't know why but I've always thought the 3.4l was a 207ci.....

  9. #9
    EFI GearHead ! EagleMark's Avatar
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    Find true bore and stroke, only change white cells.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  10. #10
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    The bore and stroke in that spreadsheet is correct.

    I also don't have old fuel pressure value either.

    Will start with the value of 138 and go from there.

  11. #11
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    The detonation is from the lack of EGR.

  12. #12
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    Quote Originally Posted by Fast355 View Post
    The detonation is from the lack of EGR.
    hmmmm......Ugh...I don't want to have to use the stock intake and egr system....

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by damanx View Post
    Hmmmmm....don't know why but I've always thought the 3.4l was a 207ci.....
    1993 Firebird 3.4L engine Bore 3.62, Stroke 3.31 = 204.4 Cubic inches and 3.34L

    Quote Originally Posted by damanx View Post
    The bore and stroke in that spreadsheet is correct.

    I also don't have old fuel pressure value either.

    Will start with the value of 138 and go from there.
    There's nothing in the BPC calculation that needs fuel pressure. The first Value of Val = 1461.5 is AFR of 14.61. If your using E fuel it should be Val = 1413.5 or whatever your fuel E content tests to.

    You could start with 138 or any number, but 143.9 is correct.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  14. #14
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    Now I am confused.

    My first calculation that included the flow of the injectors gave me a value of 142.

    Using your table, I got 138.

  15. #15
    EFI GearHead ! EagleMark's Avatar
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    Me too

    I did find a mistake in calculation of cylinder liters in the spreadsheet because of 6 cylinder, it was originally made for V8 only. But it did not effect BPC because it uses engine liters divided by cylinders entered.
    Attached Files Attached Files

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

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