GM Truck Club
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Page 1 of 3 123 Last Post byLast Post by
Results 1 to 10 of 106

Hybrid View

  1. #1

    Default I disabled AFM as an experiment.

    I used my Hypertech to disable AFM on my truck as an experiment. SO many folks are constantly talking about oil consumption, AFM makes for WORSE MPGs, etc., that I thought I would give it a try.

    With AFM I get between 17.8-18.3 MPG Monday through Friday back and forth to work.

    I disabled AFM last night and topped off the tank this morning for the drive.

    I got 20.1 MPG driving to work, which is surprisingly slightly better than what I get with AFM on. Now I know weather, fuel blends, etc., have an impact on fuel economy as well, my driving back and forth to work at least takes the terrain out of the equation.

    I will keep the forum posted.

    At the very least, I don't have to hear the AFM turn on and off and hear it on my exhaust.

    2013 Silverado LTZ White Diamond Crew Cab

    Advent OGM1 Navigation
    Husky Liners GearBox Underseat Storage
    Airaid MIT
    EGR Rail Caps
    K&N Air Filter
    Flowsound 40 Muffler
    Hypertech Max Energy Tune (only top end limiter removed and AFM disabled)
    Chrome Tailgate Handle Cover
    TonnoPro HF-155 Tonneau Cover
    WeatherTech Front and Rear Splash Guards
    Husky Liners X-Act Contour Floor Liners
    WeatherTech Side Window Deflectors

  2. Thanks ChevyFan thanked for this post
  3. #2


    So were we right?

    2009 Chevrolet Silverado 1500 LT Z71 Crew Cab "All-Star Edition"

    Line-X'd Bed
    Line-X'd Custom Brush Guard(Heavy Duty)
    5.3L Flex Fuel
    275/65R18 Toyo Open Country AT2's
    2" Rough Country Leveling Kit(want to get the 2.5 RC kit)
    EGR In-Channel Vent Visors
    Exterior PLUS Package
    Interior PLUS Package
    K&N Drop-In Air Filter
    Cat-Back Dual Exhaust
    Black Bowties
    Diablo Sport Predator(AFM Disabled)
    Towing Mirrors
    Next Planned Mods
    Blacked out Tail Lights
    Aftermarket Rims

  4. #3


    Quote Originally Posted by ChevyBoy2009 View Post
    So were we right?
    I'm not going to declare anything after only 25 miles. So far it looks promising.

  5. #4


    something to bear in mind is the fact that the ECM relearns things as you drive, so as you get more miles on it should only get better.

    at least for me, the sweet spot if running 60-65 with the cruise on. flat ground the truck returns 23 on the instant econ display, and lots of interstate driving seems to support that.


    2011 GMC Sierra SLE 5.3 Z71 4X4 Stealth Gray Metallic / 2004 Chevy Impala LS 3.8 Cappuccino

    Tow mirrors - Diablew Tuned - Flowmaster Regular 40 - Ready Lift 2.5' lift - BFG LT A/T K/Os - Carr Light Wing - TruckLite LED lights - Optima Red Top - 50% Front Window Tint - Line-X bedliner - Airaid MIT - Tekonsha P2 - ARS Billet Grill - Fia custom fit seat covers

  6. Likes mfleetwood liked this post
  7. #5


    The absolute best I ever got on my route to work for the week was 18.8MPG. Not bad for a heavy truck, but if it can do better with disabling AFM, then I'll do it.

  8. #6


    I cant wait to get my Diablo and see what kind of numbers my truck will get

  9. #7


    Stchman are your figures all from the DIC or are you doing them with pen and paper?
    The reason I ask is Ive found from experience numbers on the DIC are unreliable as they swing both high and low but never end with a true number.

  10. #8


    Mine are all from the DIC...but to be honest those numbers i have giving are higher than ive always seen taking that same looks promisng...i just love the way it handles with AFM off...feels like a "normal" truck now!

  11. #9

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    TBPLUS has a good point
    Our Prius onboard mpg-always is 2-3mpg TOO OPTIMIMISTIC
    Claims 44mpg for the tank-when filling it and dividing gives 41mpg
    Ours -Toyota -ALWAYS lies in the same direction-making our MPG look better than it really is
    That can't be a coincidence-good mpg-but a 5% lie every time.

    In any case your mpg seems about the same right Chevyboy??
    The wiki article said the AFM IMPROVES MPG 5-7% about 1-1.5 mpg-might be hard to measure any difference even if it does drop-.

    and 1 mpg-choice between excess oil consumption-and 1 mpg-if it actually works-shutting off AFM-and the oil consumption stops-well 1 mpg not too much
    But you haven't really tested your truck for oil consumption after that fix,right?
    So if consumption is less it could be GM's fix?
    Maybe do 3 tanks AFM off- 3 tanks AFM on?
    Maybe 1000 miles both ways??
    1998 suburban-
    1/2 ton

    199500 miles

  12. #10


    Sorry for highjacking your thread with the Dodge stuff Stchman, Ive created a new thread for that discussion in the coffee shop.

Page 1 of 3 123 Last Post byLast Post by

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts