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Thread: Tuning '94 chev Suburban Big Block

  1. #46
    Super Moderator dave w's Avatar
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    I've done a couple MPFI conversions, admittedly with SBC's, using the Memcal jumper. I also removed the sense resistors inside the PCM and installed solid wire were there resistors used to be installed.

    Maybe the attached .pdf files will help you set up the .bin file for MPFI? I converted the excel spreadsheet I used to modify the .bin files into .pdf files.

    dave w

  2. #47
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    Dave:

    When you converted to MPFI (batch fire) from TBI and installed the jumper of the MEMCAL, how much change, in engine running quality and, did you have to make to the off idle fuel map? The way it happened for me is that the engine ran rough. Did not have an AFR setup so don't know what happened. Will repeat with AFR setup to get clue as to what is happening. Any experience that can be shared would be greatly appreciated. Thanks for your response.

    Rolly

  3. #48
    Super Moderator dave w's Avatar
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    I use an Excel spreadsheet to "Crunch" the data log to correct the AFR's, see attached.

    I went "All In"; I modified the memcal, .bin file, and PCM resistors before I started the engine for the first time. I then went to work on the tune immediately after the initial start up.

    dave w

  4. #49
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    Dave:

    1) Trying to understand the MPFI Definitions v4_0x and how to interpret or make sense of them.
    2) When going from 2nd DRP to 4th DRP with the same VE fuel map, that should yield half the fuel to the engine thus a lean mixture. Or, is there a compensating factor hidden somewhere, wherein VE map fueling remains the same?
    3) Is the MEMCAL almost totally for limp home mode?
    4) When you went from 2nd DRP to 4th DRP on 350 engines, was there something else significant to VE map that changed?

    Please advise. Thanks.

    Rolly

  5. #50
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    Dave:

    When going from 2nd DRP to 4th DRP on the SBC engines, was it necessary to adjust fuel pressure or change injectors to a different size? Still seems like it would try to run very lean if the jumpers to MEMCAL and resistors WERE the only change. VE fuel map change? Any other changes?

    Please advise. Thanks.

    Rolly

  6. #51
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave:

    When going from 2nd DRP to 4th DRP on the SBC engines, was it necessary to adjust fuel pressure or change injectors to a different size? Still seems like it would try to run very lean if the jumpers to MEMCAL and resistors WERE the only change. VE fuel map change? Any other changes?

    Please advise. Thanks.

    Rolly
    I modified the .bin file (CHIP) for MPFI, installed the Memcal Jumper, removed the sense resistors and installed wire were the resistors were.

    Maybe you can post the .bin file you modified for MPFI? I'm wondering if maybe there is something missing / not modified in your .bin file?

    dave w

  7. #52
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    Dave:

    The most important question is, WHAT in the .bin file was changed for MPFI?
    Attached is my binary file for 1995 C1500 350 TBI 7427 0D BJYM. Found the constants for MPFI and TBI lb/hr fueling.
    How is the appropriate on (MPFI) selected? Is this done with the FLAGS section, see attached?

  8. #53
    Super Moderator dave w's Avatar
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    It appears to me the posted .bin file has not been set up for MPFI. Maybe this is not the .bin file you modified for MPFI?

    My previous post, with the .pdf files, outlines which Flags, Constants, and Tables in the .bin file must be modified for MPFI.

    I think you need to do some homework modifying your .bin file.

    dave w

  9. #54
    Fuel Injected! 1BadAction's Avatar
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    Quote Originally Posted by dave w View Post
    I went "All In"; I modified the memcal, .bin file, and PCM resistors before I started the engine for the first time. I then went to work on the tune immediately after the initial start up.

    dave w
    I agree brother, not like you can easily (mechanically) go back to TBI anyways, I don't see why anyone would want to play "just the tip" with this particular conversion. I was going to get a second computer and memcal to do this myself, but then after a few minutes of thinking about it, it hit me... WHY? If I have the kinda time it takes to go back to the TBI intake, then I'll have the truck parked and enough time to convert the ECM back also. Hell the ECM changes are the fastest out of the whole ordeal.

    Watching this thread myself, I have about 90% of what it takes to do the conversion on my Suburban. Just need to find the proper RP/Mercruiser injectors and a few other chicken shit items so I can get this thing back together in a timely manner. I hate letting a vehicle sit an extended period of time.
    2010 Porsche Cayenne GTS - DD
    1991 2500 Suburban - 454ci BBC tow monster
    1979 16' Action Marine/"Johnny Cash" Merc Bridgeport Champ Motor - Metalflake Maniac

  10. #55
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    Dave:

    That attached jpeg file has greatly added to an understanding of the conversion. Kept wondering what that table was keyed to. Now I know. Enlightening stuff. Thanks ever so much.

    Rolly

  11. #56
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    Quote Originally Posted by dave w View Post
    It appears to me the posted .bin file has not been set up for MPFI. Maybe this is not the .bin file you modified for MPFI?

    My previous post, with the .pdf files, outlines which Flags, Constants, and Tables in the .bin file must be modified for MPFI.

    I think you need to do some homework modifying your .bin file.



    dave w
    Dave:

    In your attached JPEG file, there are five changes to the FLAGS. Is this the complete extent of the changes that need to be made? What was the table formed from? Was it from the HP Tuners fellow? Please advise. Thanks.

  12. #57
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    Watching this thread myself, I have about 90% of what it takes to do the conversion on my Suburban. Just need to find the proper RP/Mercruiser injectors and a few other chicken shit items so I can get this thing back together in a timely manner. I hate letting a vehicle sit an extended period of time.
    Not to drag this too far OT, but if you have Keihin injectors I've posted some flow info.

  13. #58
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    Quote Originally Posted by dave w View Post
    It appears to me the posted .bin file has not been set up for MPFI. Maybe this is not the .bin file you modified for MPFI?

    My previous post, with the .pdf files, outlines which Flags, Constants, and Tables in the .bin file must be modified for MPFI.

    I think you need to do some homework modifying your .bin file.

    dave w
    Dave:


    In your attached JPEG file, there are five changes to the FLAGS. Is this the complete extent of the changes that need to be made? What was the table formed from? Was it from the HP Tuners fellow? Please advise. Thanks.

  14. #59
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave:


    In your attached JPEG file, there are five changes to the FLAGS. Is this the complete extent of the changes that need to be made? What was the table formed from? Was it from the HP Tuners fellow? Please advise. Thanks.
    There are three types of parameters; Constants, Flags and Tables.
    You will also need to make changes the Constants and Tables. I've previously posted .pdf files that show what Constants and Tables need to be changed.

    The MPFI conversion information was first posted on a HP Tuners website.

    Do you need help making the MPFI changes to your .bin file (CHIP)? Setting up the .bin file is a good first step. Ultimately, you will need to "Tune" the CHIP using data logs.

    dave w

  15. #60
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    Quote Originally Posted by dave w View Post
    There are three types of parameters; Constants, Flags and Tables.
    You will also need to make changes the Constants and Tables. I've previously posted .pdf files that show what Constants and Tables need to be changed.

    The MPFI conversion information was first posted on a HP Tuners website.

    Do you need help making the MPFI changes to your .bin file (CHIP)? Setting up the .bin file is a good first step. Ultimately, you will need to "Tune" the CHIP using data logs.

    dave w
    Dave:

    Thanks much for the response. Now that it is better understood, I will attempt to change the .bin file using the three posted .pdf tables. Will start with original 454 .bin file and modify from there.

    Rolly

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