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Thread: Tuning '94 chev Suburban Big Block

  1. #61
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    Dave:

    Have you used this process in the past? Has it worked sucessfully other than having to tune the VE fuel map? Please advise. Thanks.

  2. #62
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave:

    Have you used this process in the past? Has it worked sucessfully other than having to tune the VE fuel map? Please advise. Thanks.
    Yes, I've successfully used this process in the past. Tuning can include changing some of the injector values seen in the spreadsheet.

    Overall, this process can extremely challenging for a beginner!

    dave w

  3. #63
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    Quote Originally Posted by dave w View Post
    Yes, I've successfully used this process in the past. Tuning can include changing some of the injector values seen in the spreadsheet.

    Overall, this process can extremely challenging for a beginner!

    dave w
    Dave:

    Thanks much for the reply. At first blush, changing constants, flags does not appear to be that difficult. The aspect that is not understood is "...Tuning can include changing some of the injector values seen in the spreadsheet..." Hard to relate to that statement. Please expand on same.

    Regards,

    Rolly

  4. #64
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    Dave:

    Please expand on "Tuning can include changing some of the injector values seen in the spreadsheet". Which injector values may have to be changed?

  5. #65
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave:

    Please expand on "Tuning can include changing some of the injector values seen in the spreadsheet". Which injector values may have to be changed?
    Injector Flows: See attached screen shot of the previously posted spreadsheet / .pdf files.

    dave w

  6. #66
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    Quote Originally Posted by dave w View Post
    Injector Flows: See attached screen shot of the previously posted spreadsheet / .pdf files.

    dave w
    Dave:

    After looking at your .PDF files and looking at binaries in TunerPro RT, the PDF files have a Constant column, whereas TunerPro has Scalars, Flags and Tables. Don't understand the PDF file with the table labeled with Constants. At present, my 7.4L big block 16197427 is running the Edelbrock TBI to MPFI binary from their conversion chip. Attached us the Edelbrock binary. Is there a better association tables?

    Rolly

  7. #67
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    Quote Originally Posted by dave w View Post
    Injector Flows: See attached screen shot of the previously posted spreadsheet / .pdf files.

    dave w
    Dave:


    After looking at your .PDF files and looking at binaries in TunerPro RT, the PDF files have a Constant column, whereas TunerPro has Scalars, Flags and Tables. Don't understand the PDF file with the table labeled with Constants. At present, my 7.4L big block 16197427 is running the Edelbrock TBI to MPFI binary from their conversion chip. Attached us the Edelbrock binary. Is there a better association tables?


    Rolly, Ooops forgot the attachment.

  8. #68
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    Quote Originally Posted by Nasty-Z View Post
    How is the idle quality with your setup ? I wasn't able to stabilize the idle and have it be respectable with my 502 setup until I went to PFI mode with the '7427. You didn't mention camshaft so that might be a difference.

    Your setup is very similar to mine before I went with the 502 , my original 454 was also bored and stroked to 489 , although it wore first a set of Vortec heads then a set of AFR heads and a few different cams .

    TOM
    TOM: Do you have a binary file for 489 or 502 big block that works in a 16197427 ECU? Did you do the upgrades to Edelbrock TBI to MPFI injection? Please advise. Thanks.

    Rolly

  9. #69
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    Don't understand the PDF file with the table labeled with Constants.
    Rolly... You're over thinking this!

    There are three types of parameters; Constants, Flags and Tables.
    TunerPro has Scalars, Flags and Tables.
    A scalar, by any other name, still does the same job.

  10. #70
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    Quote Originally Posted by 1project2many View Post
    Rolly... You're over thinking this!




    A scalar, by any other name, still does the same job.
    Understand. The description in the LH column is different than what is presented in TunerPro for the four letter code in the 16197427 ECU. It is really difficult to get the confidence that performing the change in the binary will yield the appropriate binary for the MPFI (batch fire mode) in the 489 Big Block. There must be significant variable(s) for selecting going from TBI to MPFI. Have not yet seen these significant variables. There is one variable that describes CID for one cylinder. When multiplying by 8 cylinders, the total displacement does not work out. Hard to build confidence.

  11. #71
    Super Moderator dave w's Avatar
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    I think the Edelbrock binary (.bin) file is not for the 16197427 computer, it's only 32K in size? The 16197427 .bin file is 64K in size. Can you post the definition file (.xdf) you are using with the Edelbrock .bin file?

    The MPFI conversion is not easy for a beginner. Generally, the MPFI conversion is not the first ever experience someone starts off with. Generally, a beginner will start off with a completely stock or nearly stock engine with a completely stock binary (.bin) to learn TunerPro and learn the parameters of the .bin file. The learning curve you have set out for yourself, by choosing to do a MPFI conversion as your first .bin has put you on an extremely steep or nearly vertical uphill learning curve.

    Myself and other members here at gearhead-efi.com can provide compen$ated help if you would like to go that route? Maybe it would be a good plan for you to get the help of a "hired gun" to get you up to speed and help you build confidence?

    dave w

  12. #72
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    Understand. The description in the LH column is different than what is presented in TunerPro for the four letter code in the 16197427 ECU. It is really difficult to get the confidence that performing the change in the binary will yield the appropriate binary for the MPFI (batch fire mode) in the 489 Big Block.
    I get that. GM never released the 7427 with PFI. Even the Edelbrock calibrations I've seen are not configured exactly the same as GM typically did with PFI swaps. What we talk about here is a combination of information from several sources that attempts to make the swap in the way we think GM would do it. This is not a road frequently travelled and over the years the path has varied as well as the results. Unlike Avionics, there is no program here to ensure you are not taking a risk before you are allowed out into the world. It's ok, though. If something goes wrong with the car you can pull it over and figure out what happened. ;)

    There must be significant variable(s) for selecting going from TBI to MPFI. Have not yet seen these significant variables.
    I'm not sure what you're looking for. There is no single value that makes the switch work. A successful conversion involves changing multiple values that work together to provide correct fuel in all driving conditions. The information Dave provided gives you the best starting point you will get.

    There is one variable that describes CID for one cylinder. When multiplying by 8 cylinders, the total displacement does not work out.
    Huh??? Stock BBC cal value is 56.66. 56.66 * 8 is 453.28. Actual displacement is 453.96. How much closer does the value need to be? Maybe you are expecting a level of precision from the tune and the ecm that really aren't there??

    As far as changes related to injector strategy you will find that individual cell-by-cell tuning may be required after switching to "PFI Mode." Although the ecm calculates the correct amount of fuel to deliver based on calculated airflow and the number of injection pulses per revolution, it is not able to account for changes that occur because the manifold is not fuel soaked, because fuel is delivered at the valve, because response time during acceleration and deceleration change with the location of the injectors. When moving from four or two pulses to one, you might find that incorrect voltage compensation values meant to adjust desired "on" time affect driveablility in a dramatic way. This is another value the ecm cannot fix on its own. Additionally, you may need to do a "sanity check" on the values Dave W has posted to ensure they will work for your engine configuration. Watching the scan tool, looking at IPW and other related values is critical to help diagnose what happened.

    FWIW, one of the best and most talented "ecm hacker" type guys I knew was in Avionics. Although he spent many, many hours teaching himself code he also had an advantage over all of us trying to decipher GM code back then. Because he had access to Motorola documentation, he found that many of the tech sheets for Motorola chips and circuits designed for automotive use came with example computer code. Quite often that code and the circuit matched GM equipment very closely. Where many of us had to work with dealership repair technician service literature and do our best to RE the circuits and the code, this individual had access to insider notes from the guys who designed and often built the parts GM was using. Maybe none of that information is available today but if I had access to that library I'd be searching for anything related to GM ecm's.

  13. #73
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    Quote Originally Posted by dave w View Post
    I think the Edelbrock binary (.bin) file is not for the 16197427 computer, it's only 32K in size? The 16197427 .bin file is 64K in size. Can you post the definition file (.xdf) you are using with the Edelbrock .bin file?

    The MPFI conversion is not easy for a beginner. Generally, the MPFI conversion is not the first ever experience someone starts off with. Generally, a beginner will start off with a completely stock or nearly stock engine with a completely stock binary (.bin) to learn TunerPro and learn the parameters of the .bin file. The learning curve you have set out for yourself, by choosing to do a MPFI conversion as your first .bin has put you on an extremely steep or nearly vertical uphill learning curve.

    Myself and other members here at gearhead-efi.com can provide compen$ated help if you would like to go that route? Maybe it would be a good plan for you to get the help of a "hired gun" to get you up to speed and help you build confidence?

    dave w
    Yes I have limited experience. Right now a converted 350 Vortec with 454 TBI, adapter, modified 4 barrel manifold on an engine stand with somewhat tuned 7427 ECU. Using early build APU1 and 27SF512 Flash Memory Chips and Moates G1 adapter. Second, tuned 1995 350 C1500 pickup. Smoothed the VE fuel map and it runs near stoic most of the time. Also at the earliest, modified a 454 big block to 489 cuin and installed Edelbrock Intake (batch fire MPFI) and fuel pump. Have had some exposure at tuning TBI/MPFI systems. Would like to learn more about tuning with TunerPro. In post number 65, you provided a sample from the Constants variables.

    What is really of concern is, from what is seen in TunerPro with either the 1994-1995 0D or 0E broadcast codes, the sample injector FLOW RATES in the PDF file(s) are not included in the Scalers, Flags or Tables. In the scalars portion, under engine constants, there are listings for CPI, TBI and MPFI. Yet how is MPFI Selected?

    I understand that I could pay you to come up with a binary file. How much would it cost? Yet I would like to learn how to do same. It is becoming obvious that TunerPro is a high level front end wherein changes to one variable will change an associated Byte or Word in the Binary file. To me, it is a matter of interpretation of the terms of reference being used when speaking of variables in TunerPro.

    I just received a breakout board for the purpose of bench testing the ECU to see what happenes when changing certain variables in TunerPro. Already have the ECU connectors, with pig tails, for the 7427. Now it is a matter of connecting the pigtails to the breakout. Already have purchased MegaSquirt Stimulator Kit which should be here next week. Then assemble same. Then connect the breakout to the Stimulator and ECU. Am experienced in electronics (38+ years in Aviation Electronics) and this should not be that hard to do.

  14. #74
    Super Moderator dave w's Avatar
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    I think the attached .bin file will be EXTREMELY HELPFUL. The attached .bin has been tested, and is in use somewhere in North America.

    The original .bin file I modified for MPFI is from a very well known aftermarket EFI company. The attached .bin file requires the Memcal Jumper Modification, and the solid wire modification to the sense resistors inside the PCM!!!

    Standard Disclaimer; Use at your own risk.

    dave w

  15. #75
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    Quote Originally Posted by dave w View Post
    I think the attached .bin file will be EXTREMELY HELPFUL. The attached .bin has been tested, and is in use somewhere in North America.

    The original .bin file I modified for MPFI is from a very well known aftermarket EFI company. The attached .bin file requires the Memcal Jumper Modification, and the solid wire modification to the sense resistors inside the PCM!!!

    Standard Disclaimer; Use at your own risk.

    dave w
    Dave: Thanks very much for the reply. I will try that .bin file. Not sure what the attached .JPEG file is to represent. The attached image file is what was gleaned from the MPFI Modified $31 Aftermarket 454 Chip.BIN. Don't understand the vast differences between the two.

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