Adjusting Air Fuel mixture '7747 AKDX

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11-20-2017
57 Handyman

1 Attachment(s)

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.
11-20-2017
dave w

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
11-20-2017
57 Handyman

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?
11-20-2017
dave w

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
11-21-2017
wanderingturtle

Is the Idle Air Control valve allowing air to be pulled in?
11-21-2017
57 Handyman

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?
11-21-2017
wanderingturtle

Quote:

Originally Posted by 57 Handyman

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.
11-25-2017
57 Handyman

OK...will check that method out tomorrow. Thanks
11-25-2017
stew86MCSS396

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!!!
11-26-2017
57 Handyman

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."
12-01-2017
57 Handyman

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!
12-02-2017
57 Handyman

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?
12-02-2017
delcowizzid

If you can talk to the ecu it's probably not in limp home mode
12-02-2017
57 Handyman

delco, what do you mean by "talk to the ECM"?
12-02-2017
stew86MCSS396

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!
12-02-2017
57 Handyman

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
12-03-2017
delcowizzid

Normally full limp home mode will stop scan tools and tunerpro from talking to the ecu
12-03-2017
57 Handyman

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?
12-03-2017
57 Handyman

2 Attachment(s)

Data logs didn't upload...trying again.
12-03-2017
delcowizzid

Does it flash out any error codes for checksum failure
12-03-2017
57 Handyman

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?
12-03-2017
damanx

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
12-03-2017
57 Handyman

damanx,

Yes, those were the pins that I soldered together.
12-04-2017
dave w

Quote:

Originally Posted by 57 Handyman

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
12-04-2017
stew86MCSS396

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.
12-05-2017
57 Handyman

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.