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Thread: DFCO setting for more mileage? E38 ECU

  1. #1
    Tuner in Training
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    DFCO setting for more mileage? E38 ECU

    I have been trying to get an understanding on how this system activates as it hardly does turn on and if it does its totally random. For sure running WOT to 6K then letting off, it will show full lean which means it cut fuel. But when I'm driving around on the freeway say 2200 rpm, and let off, it would mostly not activate. And there have been other times that I'm coasting down hill and its not on for a while then all of a sudden it switches on and I feel the slight engine braking and it shows full lean on my wideband.
    I raised the throttle position enable to see if that as the problem but still does not activate. Here are my current settings. Could you help me understand why It does not turn on mostly and rarely does turn on with no pattern that I can figure out?

    Maybe Cylinder Airmass has to be changed/Raised? But is it safe to raise it?

    2013 L99/LS3 with 6L80 in a Nova
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    Last edited by reborn74; 06-16-2019 at 08:54 PM.

  2. #2
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    Anyone?

  3. #3
    Try these DFCO settings.

    Tuned L99 one off camshaft-VVT-DOD-delete-DFCO test.hpt

    You can also look at your airmass while on decel and make sure your DFCO enable settings meet the requirements. If you have decel popping and want to get rid of it, you can start raising the entry & exit spark til it stops.

  4. #4
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    Thank you.
    I played with settings today (Cylair and TPS) and am starting to get it to come on. The settings you provided I will try. But I have one question and would like to understand this a bit better.
    I noticed that the blend time for entry is significantly changed. I would like to know how does this effect the activation? Does it make it come on/activate faster?

    So far when It has come on, no popping happens. Its smooth.

  5. #5
    Senior Tuner
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    blend time i think is crank rotations so the higher the number the longer it takes to transition into or out of fuel cut

  6. #6
    Yes. From what I've seen, blend time is the time it takes to reach your DFCO spark... so the faster it gets to the entry spark the sooner it will cut fuel. You can play around with blend times and see the difference in your logs. Your logs should tell you what you need for enable settings too.

  7. #7
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    Ok now its much better. Thank you for your help. It engages a lot more now and its a bit faster. About 1.5 seconds. One thing I have noticed. When it drops its timing it goes to 10 degrees which I see is the Entry spark. But then to stays there for a tiny bit then drops to -5 degrees which is the Exit spark. Would it be wise to just make the exit the same as the entry at 10 degrees? I don't get any popping. Its smooth. But as it ramps back up when I reengage the throttle, I get knock. Not a lot...just about 1 count.

  8. #8
    Wouldn't be a bad idea to bring up the exit spark closer to the entry spark. I would personally just do stock entry/exit spark. If stock tables introduce exhaust popping you can do stock ZR1 entry/exit spark and will have zero popping and work very well.