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  1. #1
    Fuel Injected! JeepsAndGuns's Avatar
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    Have you adjusted the injector offset Vs battery voltage? Since you have installed MPFI injectors, this needs to be changed to match the new injectors as it can have a big effect on how it runs. Are you using junkyard injectors or ones from a aftermarket company?
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  2. #2
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    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
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    1992 S-10 434 SBC/Tremec - '7427
    1986 Monte Carlo SS
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 496/700R4
    1979 Corvette 496/700R4
    1977 Olds 98 Regency 403/700R4

  3. #3
    Fuel Injected! JeepsAndGuns's Avatar
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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.
    I didnt even think about that. You did do all the required mods to run MPFI right?
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  4. #4
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    Quote Originally Posted by JeepsAndGuns View Post
    I didnt even think about that. You did do all the required mods to run MPFI right?
    As I explained to TOM, the Edelbrock conversion was done some 8 years ago. Unaware of all this stuff when it was done. Worked fairly well. Used Moates APU1 to make changes about which I knew absolutely NOTHING! Still it worked out after capturing the Edelbrock binary supplied on their chip. Also purchased another programmed chip from which to extract data, although I had little idea about what I was doing. Still puzzled as to what the ECU mods really do. Still have not done them and yet the stock, with exception of the flash chip, ECU and Engine run just fine.

  5. #5
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    Gentlemen: Just to provide some background about myself, I really like working on Internal Combustion Engines especially the Small Block Chevrolet. It is a compact package capable of much horsepower depending on how much a person spends on building up one. I was in Aviation Electronics, known as Avionics, for 38+ years. Electronics is nothing new to me. Yet, getting through TunerPro RT V5.x is somewhat of a challenge. Have read many of the posts here on gearhead-efi. Am very greatfull for this Internet Site as it has been a wealth of knowledge. Many of you fellows have extensive knowledge just through exposure doing your own GM EFI projects. A special thanks to Dave W. as he had been VERY helpful. I have two chevrolet trucks that I work on. One a 1994 BBC Suburban and the other a 1995 Chevrolet C1500 2WD pickup that is in good condition except it leaks and uses engine oil. Am preparing a 350 Vortec and will be using a BBC TBI throttle body on top of a 4 barrel manifold with adapter. Just added a LT-4 Hot Cam to the Vortec and today the stronger Crane Cams valve springs came via UPS. Need to install these and mock up and set the fuel pressure regulator on the BBC throttle body. Then run the Vortec on my home brew run-in stand with a Holley 4 barrel carb. Also have a harness for the 16197427 ECU. Shall see if I can get the harness and BBC throttle body all mocked up on the run-in stand which provides NO dynamic load whatsoever to the Vortec. At least I can check for oil leaks etc. before installing same in the '95 pickup.

    It is nice to have you fellow to consult with.

    Regards,

    Rolly
    Tucson, Arizona

  6. #6
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    if you have a multiport intake and injectors I have no idea why you would want to run them in a tbi fueling mode. ya it'll run but leaves a lot on the table no?

  7. #7
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    Quote Originally Posted by tayto View Post
    if you have a multiport intake and injectors I have no idea why you would want to run them in a tbi fueling mode. ya it'll run but leaves a lot on the table no?
    The calibration from Edelbrock runs the 8 MPFI injectors in a batch fire mode , this setup is not a "true" MPFI setup but rather a small upgrade to get the fuel flow from the factory TBI out of the air stream and directly into the ports. The 16197427 will not support true MPFI.

    As I said in my earlier post , I tried to use the factory Edelbrock calibration on both my original 454 and the replacement 502 (509) in the '7427 , It ran OK , but I believe it left a lot on the table with the PCM in the original TBI mode. I switched to PFI mode in the PCM (Jumper mod only , no sense resistor mods) and it runs and idles much better.

    Just my experience , the OP states his idles just fine the way it is so he should be good to go.

    TOM
    Last edited by Nasty-Z; 01-22-2015 at 05:21 PM.
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    1992 S-10 434 SBC/Tremec - '7427
    1986 Monte Carlo SS
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 496/700R4
    1979 Corvette 496/700R4
    1977 Olds 98 Regency 403/700R4

  8. #8
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    Tom:

    No problems with idle quality after installing Edelbrock TBI to batch injected MPFI via the 16197427 ECU. Did not know about the injector offset vs battery voltage. The conversion was done some 8 years ago. Purchased Craig Moates AutoProm APU1 which was of the initial production run. Talked to Craig and received some advice from him. Unaware about modifying the ECU and Edelbrock said nothing about it. Just did the conversion and it worked out. The Edelbrock kit (chose 502 cu in kit w/29 Lb/Hr injectors) came with new Intake Manifold, new Magnetti Marelli Pico Injectors, new fuel pump, and new programmed memory chip for ECU and other small hardware.

  9. #9
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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

  10. #10
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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.

  11. #11
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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.

  12. #12
    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

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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.

  14. #14
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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.

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