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Thread: 5.7L running too lean (very high NOx), won't pass state emissions

  1. #31
    Fuel Injected!
    Join Date
    Mar 2017
    Hey I am providing an update. I received and installed the 1227747 ECM with the factory ASDU chip. It started right up and after a warm up period I disconnected the distributer connector and set the base timing to exactly 0 degrees TDC. Previously, it was 2 degrees advanced. Then i ran TunerPro and created another log file. There seems to be some significant improvements. First it idles at 750 or so instead of 1150, but much more importantly at part throttle is now seems to be operating much better flipping back and forth every few seconds between Lean and Rich and the O2 sensor output voltage also seems to be alternating above and below .500. Previously, part throttle seemed to stay just Lean most of the time.

    I do have one question though. The vacuum and MAP numbers seem to pretty much remain constant regardless of throttle position. I don't understand this. Shouldn't the vacuum and MAP numbers drop as throttle increases?

    If someone could look at the attached XDL file it would be appreciated.
    Attached Files Attached Files

  2. #32
    Electronic Ignition!
    Join Date
    Jun 2015
    What is your compression ratio and what plugs are you running? I know you've got other things working against you and you're sorting them out, but running plugs that are too hot will also have a huge effect on NOx

  3. #33
    Electronic Ignition! De-stroker's Avatar
    Join Date
    Feb 2017
    Casper wy
    I cant open your file so im just stabbing, that engine is gonna run cold if the air gets under it, my 5 speed trucks' oil got so cold that it lost a rod bearing it was always at 1500-2000 when it was running I don't think you have a computer issue, U will be able to tell if the injectors are firing right. does it spray consistently through the rpm? Not saying that's an easy issue you have.
    Last edited by De-stroker; 2 Weeks Ago at 06:49 AM.

  4. #34
    Fuel Injected!
    Join Date
    Mar 2017
    Good point. I am running Platinum E3's (4-prongs). I will probably go back to standard AC Delco's.

  5. #35
    Fuel Injected!
    Join Date
    Mar 2017
    I don't think this is part of my problem as the engine actually runs on the hot side - probably because it is mounted in a Jeep Wrangler, I live in a warm climate, and don't go 4wheel'n in the snow during the winter months. But I will check the injectors spray pattern across RPMs.

  6. #36
    Carb and Points!
    Join Date
    Dec 2016
    There is a lot more experience in this thread than I have, but I will toss something out I ran into.

    My suburban started running bad and I could see it in the data log it was running extremly lean and it was obviously much worse than yours is. I finally traced it down to one of the injectors being badly clogged and it wasn't flowing enough fuel. It was so bad you could see that one side wasn't like the other side. Both injectors were probably dirty and running lean, just one was really bad! I bought two new units and that fixed mine, if the chip doesn't fix that you might have dirty injector(s).

  7. #37
    Fuel Injected!
    Join Date
    Mar 2017
    Lack of fuel would definitely cause it to run lean. As soon as I get my computer back, I will carefully check the spray pattern. Moates is replacing the 24 pin socket and soldering in a new 28 pin socket. Once I get it back, I will drop in the ARJU (California) chip then check everything out.

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