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Thread: 85 IROC TPI 1227730 conversion from 1226870

  1. #61
    RIP EagleMark's Avatar
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    Glad you got it working as planned!

    All writeups to tech issues are always welcome! Pictures help as well.
    This could be the first of many memcal mods that need to be documented, we have a couple on installing chips and zifs, but really need to put together all the jumper and ground changes needed for 6 and 8 cylinder TBI and MPFI all together as one article.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  2. #62
    Fuel Injected! zaut's Avatar
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    Mark. I created a powerpoint on what I did. Please review and post it in the tech articles if you think it is worthy.

    ***** I fixed the typo on the V8 Jumper and added another comment that the MEMCAL mounted Knock Filter needs removed. *****
    Last edited by zaut; 04-27-2012 at 03:28 AM.

  3. #63
    you have the jumper labeled incorrect it's 56 to 62 ground.

  4. #64
    Not sure how this would effect this but a p knock board measure 155k form cal29 to 31 and a R board is 195k

  5. #65
    RIP EagleMark's Avatar
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    Tunedperformance has more experiance at this than I do and would be the one I would ask, so when it is agreed I will make a spot for it with your name as contributor.

    Tunedperformance, whenever you want to put together a Memcal article we would all know what to do, what to get or where to buy! I would not only have it in the write up section but build a permanaent webpage as well. You would be welcome to have contact info to sell your products as well. Like this:
    http://www.gearhead-efi.com/gm-ecm-p...onversion.html

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

  6. #66
    Thank you eaglemark. I think the credit of this would goto zuat. I honestly have only one v6 to v8 memcal for a buddy and just deleted the knock. The v6 to v8 jumper is the same for the 427 to mpfi or a 86-89 tpi maf netress and i/o will operate in a 730 ecm just change the .bin and delete knock from the programing. Mr Rbob knows more on this subject

  7. #67
    Fuel Injected! zaut's Avatar
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    Tunedperformance, Thanks for catching my mistake. I fixed the typo on the V8 jumper slide. My guess is that the resistance from cal29 to CAL31 makes no difference.
    Here is my impression of what is going on:
    GM is cheap, they basically are using the same electronics with the knock mounted filter as the separate ESC module. They cut cost by eliminating the wiring to the ECS and the ESC packaging. CAL31 is the knock module ground, CAL30 is the knock +12V, CAL29 is the KNOCK sensor input, and CAL32 is the Knock filter output to the ECM. They just repackaged the ESC to piggy back on the MEMCAL module to cut out cost. If you compare the CAL29,30,31 and 32 connections, you will see they mirror the connections of a ESC module. And since both the ESC module and the MEMCAL knock filter go to the same node in the ECU, I am sure both modules put out the same signal if they see knock. The signal is just a "o" until the knock is gone. The logic inverter sends a "1" to the CPU saying there is knock present. The software, via the retard attack rate retards timing until the filter outputs a “1”. This is my educated guess on how it works.
    Last edited by zaut; 04-27-2012 at 03:49 AM.

  8. #68
    Fuel Injected! zaut's Avatar
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    Wow, I thought I would get some responses as to the validity of my theory. I have been using the ESC module for a week or so now. I do get occasional knock induced timing retard. The file above has been corrected for the V8 jumper typo. I would recommend it be added to the tech articles.

  9. #69
    Quote Originally Posted by zaut View Post
    Wow, I thought I would get some responses as to the validity of my theory. I have been using the ESC module for a week or so now. I do get occasional knock induced timing retard. The file above has been corrected for the V8 jumper typo. I would recommend it be added to the tech articles.
    this theory ?While poking at an ECM chasing signal paths around, I found aninteresting input/output pin. In the 1227730/1227749 ECMs, harness pinB8 might be the filtered knock sensor signal. It connects via a 10Kresistor to the input of a (digital) inverter. The inverter input isdirectly connected to one of the MEMCAL pins which connects to thehybrid knock sensor filter module. The inverter input is also pulled toground through a 470K resistor, and clipped to 5V via a diode.It appears that if a MEMCAL contains no knock filter, pin B8 could beused to input a signal from an external knock filter. If the MEMCALdoes contain the hybrid module, pin B8 would be an output.If used as an output, it would need to feed a circuit with a highimpedance input (because of the 10K resistor). Someone with a knocksensor equipped 730/749 vehicle should hook a buffer and light to pinB8. It would be interesting to hear when/if the light turns on.-- Ludis Langens http://www.diy-efi.org/gmecm/archive.../msg00712.html

  10. #70
    Fuel Injected! zaut's Avatar
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    Tuned performance, as you point out and I agree that I used information found on several message boards to make a conscious decision to try the ESC module as I describe. What I found lacking everywhere I looked was someone confirming that it worked. In no means do take credit for the discovery. My theory is on GM repackaging the knock filter on the MEMCAL to save packaging and wiring cost. The document I created merely consolidates everything I found online that lead me to believe the ESC module will work in place of the MEMCAL filter. I spent many hours learning this stuff and am very grateful for all the help I got here. I was only trying to give back for everything I was given.

  11. #71
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    Tuned performance, as you point out and I agree that I used information found on several message boards to make a conscious decision to try the ESC module as I describe. What I found lacking everywhere I looked was someone confirming that it worked.
    Which probably explains the lack of discussion on the theory. I don't know anyone who's spent time using the external knock circuitry instead of the memcal circuit. I haven't. I've always been lucky enough to match up a memcal to an application in one way or another. GM is cheap and what you're thinking is right in line with what GM might do. But it may take more time and more people testing this and see if it actually works as intended.

  12. #72
    Im curious to see how the aussie's tunable knock filter on there nvsram would work in a 730.

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