Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 1 of 2 12 LastLast
Results 1 to 15 of 26

Thread: Adjusting Air Fuel mixture '7747 AKDX

  1. #1
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99

    Adjusting Air Fuel mixture '7747 AKDX

    Need assistance in modifying the bin to address the following condition:

    I have a modified '7747 ECM with a 28-pin ZIF socket installed in my '92 4.3L S-10. I burned the attached AKDX.bin file onto a 28-pin EEPROM which is now running in the truck. Yesterday, after running for a few minutes, the engine died and would not restart. While attempting to restart, I noticed a heavy spray of fuel flowing into the throttle and observed liquid fuel collecting on the rear edge of the throttle plates. I opened the throttle wide-open, hit the remote starter button and the engine struggled to restart but did eventually restart. I had to manually control (open and close) the throttle in order to keep the engine running; if I let it go completely the engine would die.

    Because of the heavy fuel spray, on the next restart attempt, I disconnected the driver injector wire and cranked the engine with throttle partially open. The engine started a little easier but continued to ran rough. Once I reconnected the injector wire, the engine struggled again to stay running and I had to manually open and close the throttle in order to keep the engine running. Again, if I let go of the throttle completely, the engine would die.

    Is this flooding condition due to the ECM holding the injector pulses open too long? Can it be adjusted in the .bin? What specifically do I need to do and is the needed adjustment only required in one place within the bin file?

    Thank you in advance.
    Attached Files Attached Files

  2. #2
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
    Posts
    3,411
    What Offsets did you use to burn the 28 pin chip? I'm thinking you are using a 27SF512 Chip, which is 64K. The posted ,bin file is only 4K.

    http://support.moates.net/programmin...using-offsets/

    dave w

  3. #3
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    Hi Dave,

    Thank you for looking at my dilemma.

    I believe the offset was what is required for a 4K bin file. I used Flash & Burn with an APU1 to burn the chip. If I remember correctly, I entered the necessary information on chip type and verified the offset and buffer values were correct. Once I completed the burn and installed the chip, I assumed I had done the burn correctly because the engine started and ran. Am I mistaken?

    So, are you saying that if I burned the chip with an incorrect offset that that is causing my problem of too much fuel spray? Or, is the ECM running in limp home mode?

  4. #4
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
    Posts
    3,411
    A stock 24 pin chip can be installed into the 28 pin ZIF socket, once the stock chip is removed from the original holder. I would try a stock chip in the 28 pin socket and see if it makes any difference in the way the engine will run. When installing a 24 pin chip into a 28 pin socket, PINS 1,2 27, & 28 are open. It's also possible to install a chip backwards into a 28 pin socket, VERIFY PIN 1.

    If a chip is incorrectly programmed, the engine will run in a limp home mode (too much fuel).

    We are assuming the 28 pin ZIF socket was correctly modified for the EEPROM and correctly installed into the '7747?

    dave w

  5. #5
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    37
    Posts
    66
    Is the Idle Air Control valve allowing air to be pulled in?
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  6. #6
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    Thanks Dave for the info that I can insert the original 24-pin chip in a 28-pin socket. I did not know that was possible. I just hope I correctly modified the socket and installed it properly without damaging the ECM. Just to ensure I used a correct buffer setting, I will re-burn the chip.

    wanderingturtle, I had installed a new IAC but have no way of knowing air is being pulled in. How do I check that it is functioning properly?

  7. #7
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    37
    Posts
    66
    Quote Originally Posted by 57 Handyman View Post
    wanderingturtle, I had installed a new IAC but have no way of knowing air is being pulled in. How do I check that it is functioning properly?
    Well, with the air cleaner and throttle body sleeve (part name?) removed, you can put your finger in the IAC passageway hole and feel and listen for if air is sucking by when cranking.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  8. #8
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    OK...will check that method out tomorrow. Thanks

  9. #9
    Fuel Injected!
    Join Date
    Jan 2017
    Posts
    33
    When initially started the engine, Stuck my finger down into that hole and could feel the air bypassing. At the time, we had the key "on" engine "off," the scanner was reading 145 which is the "park" position set in the ECM. At this point, we could have jumpered pin A to pin B on the ALDL and watch the IAC close to 0 on the scanner. 2nd time running, scanner was hovering around 39. I think it's working fine, time to move onto bigger things!!!

  10. #10
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    OK, thanks Stew. I didn't know you had already gone thru that process to verify/validate proper operation of the IAC. With that done, I agree with "time to move onto bigger things."

  11. #11
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    Dave W: I did a re-burn of the chip and verified the settings for buffering and addressing were correct per the MOATES notes for a 4K bin file. I installed it into my ZIF-modified 7747 and it appears the initial issue of too much fuel at restart remain. If I depress pedal to the floor, I can get the engine to start and run. Once started, it idles okay. BUT, that still doesn't indicate whether my modifications to the 7747 have not damaged the ECM.

    With Stew's assistance, I borrowed and ran his stock 7747 AKDW. Motor start up was good and idled smoothly. I wasn't able to run a 24-pin AKDW since they are in holders and I don't want to mess them up. Stew will burn me a 24-pin AKDW tonight which I will then test in the 28-pin ZIF (per Dave W's advice) to see if my ZIF-modified 7747 is functioning properly.

    Thanks for helping!

  12. #12
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    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?

  13. #13
    Fuel Injected!
    Join Date
    Jul 2013
    Location
    Newzealand
    Posts
    440
    If you can talk to the ecu it's probably not in limp home mode

  14. #14
    Fuel Injected!
    Join Date
    Jan 2013
    Age
    71
    Posts
    99
    delco, what do you mean by "talk to the ECM"?

  15. #15
    Fuel Injected!
    Join Date
    Jan 2017
    Posts
    33
    Between Kalama Valley runs, managed to install 28 pin zif into ‘747. You’re welcome to try it out. Gonna hafta be around lunch time and only drop off. Gotta go back work!

Similar Threads

  1. 7747 fuel relay and diverter valvet on key up
    By 74L19 in forum GM EFI Systems
    Replies: 2
    Last Post: 08-16-2017, 10:09 AM
  2. 7747 - higher fuel consumption with VSS installed
    By Dr_Grip in forum GM EFI Systems
    Replies: 7
    Last Post: 12-28-2015, 05:59 AM
  3. fuel curves for 7747 running stock vortec shortblock
    By ODDDOYLERULES in forum GM EFI Systems
    Replies: 30
    Last Post: 11-30-2013, 03:11 PM
  4. First time start up, too much fuel. 350 chev 7747,
    By live2wheel in forum GM EFI Systems
    Replies: 19
    Last Post: 07-02-2013, 04:58 PM
  5. Adjusting BLM
    By ggenovez in forum TunerPro Tuning Talk
    Replies: 26
    Last Post: 04-26-2012, 03:52 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •