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Thread: Leaner AFR during cruising

  1. #1
    Senior Tuner metroplex's Avatar
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    Leaner AFR during cruising

    I was reading this article https://www.thedrive.com/news/31400/...rolet-corvette

    And was wondering if it was possible to do this on newer Ford's? The Corvette ran as lean as 17:1 at light throttle conditions.

  2. #2
    Advanced Tuner
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    I would say it's engine and fuel dependent. If you are running a detonation resistant blend with ethanol or methanol you can get pretty lean without pinging, lower DCR could possibly get away with it also. You could also change your DFCO settings to cut fuel faster, change your WOT settings to a higher pedal value, lower your throttle sensitivity. Is cranking up afr 2-3 points to save 10-15% fuel under very low loads (a fraction of your driving) worth the risk? I don't know... Not for me, I am not good enough at tuning or detecting problems, engines cost more than gas, and are harder to replace.

  3. #3
    Senior Tuner CCS86's Avatar
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    The biggest hurdles I see:

    - Copperheads don't have a desired equivalence ratio vs load table.

    - At low load you just have the defined stoich ratio, which you could fudge, but widebands will always bring back to stoich.

    - You could put the power enrich pedal at 1% to force a non-stoich Lambda, but the only table governing then, is the CL Lambda table (Lambda vs RPM vs ECT). It would really need to be [Lambda vs RPM vs Load] to work well.

    I really wish I knew of software that would let you hack these aspects of the factory calibration structure (table dimensions, channels referenced for axis values, etc...)

  4. #4
    Tuner in Training
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    That would be a good idea to make the EQ ratio leaner at low loads like in GM. Looked everywhere but couldn't find a way to do that. I wonder why it is not possible ?

  5. #5
    Senior Tuner SultanHassanMasTuning's Avatar
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    as long as you have the o2 feedback working with ford and using lambda sensors targeting 1 it would be impossible

    unless you just tune for OL
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  6. #6
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    You could try to move the ECT scalars for the cold base fuel table to use that 100% of the time. Not sure how well it would work.

  7. #7
    Advanced Tuner
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    With tivct I don?t think there is any advantage. Leaning out at cruise makes the engine more efficient but the mechanism isnt intuitive. By leaning out, you?re still getting the same BTu?s from the same amount of gasoline but it requires more air because that?s what you told it to require. The result is a higher throttle opening, manifold pressure, and less pumping losses. The 1999 vette had fixed cam timing and displacement, so there was no other way to reduce pumping losses. The coyote has tivct so it retards the intake cam at cruise, which results in higher manifold pressure for the same air load, to achieve the same result.

  8. #8
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    You can achieve better mpg with the cam angles using the fuel economy distance tables. O2 sensors will always target stoich.