Leave AFM Off or On? Really any difference in MPG?

Discussion in 'Performance' started by Tylus, Jul 11, 2019.

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  1. Tylus

    Tylus Full Access Member

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    Jeremiah
    Edge Evolution CS2 on Level 3
    AFM turned off
    Tire correction factor for my larger than factory tires


    My around town MPG appears better and highway a tad worse. I'm about to drive 1600 miles round trip. Will turning AFM back on gain me anything WHILE keeping the tune? Looking for input from those who've driven long distances tuned with AFM ON vs. OFF.
     
  2. iamdub

    iamdub Hold on... Lemme overthink this for a bit...

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    I've only had one long trip with AFM on and one with it off. Straight highway, I lost 2 MPG with it off. With my 195K-mile '08 with a lifter that ticks for a few seconds at startup, I keep it turned off. If your trip will be steady cruising on mostly flat land at speeds no more than 70-75, then you should benefit some from AFM.
     
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  3. BigBlueLB756

    BigBlueLB756 Full Access Member

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    I just recently traveled from MS up to Indy area and back. 1521 miles. 22.1 mpg. Tuned w/ AFM off. Catch can working. Very satisfied with Tahoe performance. Caught this snot:
    100_0778.jpg
     
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  4. Tylus

    Tylus Full Access Member

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    Well just drove to Savannah today and back. About 300 miles round trip at 73mph

    20 mpg with wicked headwinds and rain

    AFM was on. But it never went into V-4 mode. Guess I’ll just turn AFM back off in the programming.



    For reference my 2015 Tahoe averaged 23 mpg in 2016 when I drove across country from LA to NYC. 20+ mpg tuned is decent in my eyes
     
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  5. swathdiver

    swathdiver Full Access Member

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    Not bad, I've lost 2-3 mpg just driving on wet roads at highway speeds before!
     
  6. pt1965

    pt1965 Member

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    wow, i have the lc9 with afm, but the best i have done on extended trip is 18mpg! doesnt matter if i go 70 or 80. most of the time its 16-17 mpg.
    whats the secret??
     
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  7. Tylus

    Tylus Full Access Member

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    Suburban
    2.5” leveling kit
    33” tires (e-rated)
    Level 3 programming (street tune) with AFM on

    CRUISE CONTROL!!!!

    Lol. Drove 524 miles at 71 mph. Got 20.3 MPG hand calculated. Lie-o-meter said 20.9 mpg. That was 1 tank of gas for 524 miles

    Drove another 180 miles at 62 mph and got 23.9 mpg.


    The biggest influence is consistency. Put cruise control on and just cruise. Resist using right pedal
     
  8. BG1988

    BG1988 Full Access Member

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    have you verified the speed via GPS

    try 59MPH? I get 25 to 28mpg..


    36MPG-e-assisted seem pretty average in the city.. by manipulating the hybrid module and AFM .. and manipulating the acceleration ...


    0 to 30 in EV mode (electric motors) then 30 to 41 on the ICE

    41= 40-43MPG instant... =36-38MPG IRL



    Then if I see a stop slight ahead i drop it to 29mph so it will switch back to EV mode...


    this is basically the most fuel efficient possible way to drive the SUV....


    basically the engine is just sitting there idling at 1050-1150rpm in v4 mode
    using tiny amounts of gas..



    I really Wish i could enter auto stop at higher speeds on downhill
    other hybrids can do it but not this suv... this would save a ton of gas :)
     
    Last edited: Jul 16, 2019
  9. swathdiver

    swathdiver Full Access Member

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    PT, Jeremiah's secret is his Direct Injection motor, he's not driving a GMT900, he's got a K2!
     
  10. swathdiver

    swathdiver Full Access Member

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    HP Tuners or EFI Live!?
     

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