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Thread: Adjusting Air Fuel mixture '7747 AKDX

  1. #16
    Fuel Injected!
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    Oh, WOW...guess you did find something to do while your wife was in Hawaii Kai...lol. Rather than you dropping it off, I'll come to you so you don't loose your preferred parking. Plan on going to JBPHH abandoned vehicle auction and swing-by around 1100 or so. Thanks, Stew

  2. #17
    Fuel Injected!
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    Normally full limp home mode will stop scan tools and tunerpro from talking to the ecu

  3. #18
    Fuel Injected!
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    Thanks Delco,

    So, when you say "full LHM will stop scan tools and tunerpro from talking to the ECU", I shouldn't be able to do any data logging? I was just hooked up to my 7747 via my APU1 and was able to record some data (attached). But I have no idea if these recordings are good as only a few parameters seemed to be responding to throttle changes. Does this level of data logging indicate the ECM is not running in any level of LHM?

  4. #19
    Fuel Injected!
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    Data logs didn't upload...trying again.
    Attached Files Attached Files

  5. #20
    Fuel Injected!
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    Does it flash out any error codes for checksum failure

  6. #21
    Fuel Injected!
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    Delco, I am new...very new...to tuning and using TunerPro. I did not notice any specific codes for checksum failure. There were NO flashing Codes. I checked by shorting Pins A & B on the ALDL. Would I see that in TunerPro?

  7. #22
    Fuel Injected!
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    Also, when you put the 28 pin ZIF socket in, did you solder pins 1,2, 26-28 together as seen in this picture?

    http://www.gearhead-efi.com/Fuel-Inj...4&d=1404856990
    Last edited by damanx; 1 Week Ago at 12:39 AM.

  8. #23
    Fuel Injected!
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    damanx,

    Yes, those were the pins that I soldered together.

  9. #24
    Super Moderator dave w's Avatar
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    Quote Originally Posted by 57 Handyman View Post
    Update: Received the 24-pin AKDW chip (with EGR deleted) and installed it in my ZIF-modified 7747. Unfortunately, the results were the same--slightly rough idle and too much fuel during restarts. As Dave W indicated earlier, one of the symptoms of running in Limp Home Mode is too much fuel. Since I've tested several 28-pin chips in the ECM and, thereby, eliminated that the problems are with the EEPROMs, the remaining conclusion is I messed up my 7747 while installing the 28-pin ZIF socket.

    Before I toss the ECM out, is there a sure-fire way of determining the ECM is indeed running in Limp Home Mode? Is there software available that will read this via the ALDL? If I removed the LHM chip and leave in only the AKDW, will a "no start" indicate that the ECM was indeed running in LHM?
    One method of troubleshooting is to "Bookend" the problem. It seems we have one "Bookend" established, (if I'm understanding correctly) good chip / good ECM engine runs OK.

    There was a day and time, my soldering skills needed improvement, likely still do for some surface mount components. Thru hole soldering, like the '7747, is about as basic a soldering project gets. I would use my OHM meter on the ZIF modified ECM that was soldered and compare those measurements with a "GOOD" ECM. I would measure resistance from pin 1 / pin 2, then pin 2 / pin 3, then pin 3 / pin 4 .... ending with pin 11 / pin 12. Then repeat the OHM measurements pin 13 / pin 14, then pin 14 / 15, then pin 15 / pin 16 .... ending with pin 23 / pin 24. I would also measure the modified ZIF pins. Ohm measurements should be within 1% from known good ECM to the ZIF modified ECM. Maybe re-solder pins that show a resistance of more than 1%, if there are any. If everything measures within 1%, I would be "STUMPTED" as to what is causing the rough idle and rich fueling.

    dave w

  10. #25
    Fuel Injected!
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    That's some sound advice. I felt a little rushed installing the 28 pin zif and wondered if I may have not clean the contacts good enough. I've done the OHM measurements on another '7747 I have here and can compare with modified ones at the shop. If yours don't check out, the offer still stands that I can try re-solder your '7747. I really need to get one of them magnifying glass with a good light. After staring at it too long, everything gets a little blurry. Based on the IDLE datalog, I'd like to pull some fuel out to see if idle improves, but if none of the initial adjustments are done/verified, I feel it's going to be an uphill battle.

  11. #26
    Fuel Injected!
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    Dave W, thanks for providing a way to test the results of my soldering. I will follow the steps you outline above. Hopefully, any differences in resistance will be minimal.

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