I disabled AFM as an experiment.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by stchman, Aug 26, 2013.

  1. stchman

    stchman Active Member 2 Years 1000 Posts

    The fuel economy numbers were about the same with AFM enabled. When I filled up I would get anywhere between 16.5 to 18.0 according to the DIC, so this last tankful was slightly better according to the DIC, but one tank is not considered a good sample size.

    I gather that is I drove straight level highway at 65MPH all the time where AFM could stay in V4 mode for alot longer, fuel economy might be better.

    My 2013 Silverado now has ~14K miles and the engine should be nice and broken in now, so I should be getting better MPGs.
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Are you still testing your mpg?
    Has it gotten better or is it still getting between 16-18 mpg?
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    So far-no noticeable difference in FE?
    Pretty sure hyper milers-could show 2 mpg difference in suburban driving
    but they would drive with a eye to getting the 4 cyl mode to kick in
    Does the onboard screen TELL you when it goes 4 cylinder?
    Seems like on another forum-someone mentioned 2 cylinders??-or maybe it was the new 4.3(which gets GREAT MPG by the way and makes about 300 hp). In any case the new 4.3 is now a desirable motor
    It used to be the 4.3 was the motor you bought because you didn't want to pay $4000 more to get the higher trim level truck that the 5.3 came in.
  4. stchman

    stchman Active Member 2 Years 1000 Posts

    I filled up Monday morning and was getting 17.8MPG.

    So far fuel economy has not changed appreciably from when AFM was enabled.
  5. stchman

    stchman Active Member 2 Years 1000 Posts

    I filled up this morning and here is the DIC and hand calculated numbers:

               Miles Driven    Gallons Used        MPG
    DIC          326.1            18.1             18.0
    Hand Cacl    326.1            18.6             17.5
  6. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    17.5 pretty good-about what you said pre disabling MPG was
  7. undertheradar

    undertheradar Rockstar

    you take that thing on a 400 mile trip and you'll get 21 mpg. I get 17-18 depending on the gas I get. Starting and stopping just 5 or 6 times during the trip to work is what kills my mileage. I have 308 gears with 2856518 nittos. I want to regear BAD. Mine wont get out of its own way unless I stomp it.
  8. IronBear

    IronBear New Member

    I also have 308 gears and my truck is a slug as well, but that's the least of my worries. It's still hesitating when warm, and the engine 'ticks' (after sitting over night) when you first start it. I'm bringing it into the dealer tomorrow.
  9. Jeff Dodson

    Jeff Dodson Member 1 Year

    Afm...... ?
  10. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    Active Fuel Management

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