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Thread: Working on an E78 ecm lean on idle need some help

  1. #1
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    Working on an E78 ecm lean on idle need some help

    finished swap instale l96 6.0 with 6l90e all runs good however it is lean at idle. I have read and looked all through out the tune and can quite figure out what i need to change to richen the idle this would be in close loop after it get to temp.
    also has any one been able to get the Efans working i have two swaps with the same set up and i would like the fans to work,,
    'thanks in advance.

  2. #2
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    Why do you say it's lean at idle? In closed loop up to temp the fuel trims should be trimming it to stoich. Are the fuel trims + ? Even if they are it should be running at stoich.

  3. #3
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    yes at idle, the fuel trims max out and it still asking for more fuel close loop i get a lean even and odd bank ces light

  4. #4
    Tuning Addict 5FDP's Avatar
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    What's your fuel pressure?
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  5. #5
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    60 lbs im going to check for an air leak tomorrow

  6. #6
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    lean idle

    here is a idle scanne log file check it out let me know what you think
    Attached Files Attached Files

  7. #7
    Tuning Addict 5FDP's Avatar
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    What is the intake setup? Factory MAF sensor in a stock size MAF tube?

    Does it have exhaust after the o2 sensors?
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  8. #8
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    Quote Originally Posted by 5FDP View Post
    What is the intake setup? Factory MAF sensor in a stock size MAF tube?

    Does it have exhaust after the o2 sensors?
    4" pipe all the way i side the cab 3 90?s teo 45s all sealed maf is installed with in a foot or so from throttle body

    2 1/4 exaust after shorty headers flowmaster muffler

  9. #9
    Tuning Addict 5FDP's Avatar
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    The stock MAF housing on the airbox isn't 4 inches round so if you made yours 4in then this is where I see your problem.

    You'll have to re-do the MAF curve to dial things back in.

    As a test you could add 5% to the entire MAF airflow table, then see what happens to your fuel trims.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  10. #10
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    Ill try that a bit and post back here

  11. #11
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    That was it thank you! Runs way better!

  12. #12
    Tuning Addict 5FDP's Avatar
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    Remember that was just a quick test to see what you need to do. Now you will want to take the time to make sure the whole curve is correct. Ideally using a wideband to make sure fueling is correct at not only part throttle by at full throttle where you will have no fuel trims to correct it.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  13. #13
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    Absolutely we add till it was adding and or subtracting fuel now it hangs close to 6%+-
    There is a few areas at 10% or so but way better than what it was. Hes going to drive it some then we will revisit.
    Last edited by Littlepiston; 02-29-2020 at 05:36 PM.