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  1. #1

    Default 2010 Chevy Silverado AFM Engine Problems or not??? Fuel mileage? 5.3 engine AFM

    I have recently purchased a 2010 Silverado with a 5.3 with 35xxx miles. When I test drove the vehicle it drove great. Now that I have had it a few weeks I have noticed it seems to make different sounds mainly I think when the active fuel management starts working. I am not getting that good of gas mileage, I was hoping for 18-19, I am however getting 16-17. the truck is bone stock. I have been trying to drive half way decent to see what the highest mileage is I could get. I have started to notice that when you are coming off of cruising thottle to accelerate it makes different noises almost like a skip.

    i know it isnt skipping, otherwise it would log a dtc. My question is, Why kind of mileage is everyone else getting? i never see a light or indicator when the afm is working. Is this normal on this model ? I have read alot of posts where people wanted the afm removed simply because of the different sounds or feeling when it works. i dont mind so much, i would care less if I were getting better mileage.

    Just a little about myself, I am a master tech we lost our gm badge right after obama made gm obama motors. (we were one of the medium dealers that got a pink slip). I do however currently have a tech2 in the truck, we dont have access to tsb's now. But, I have all kinds of toys to play with. . i have been working on gm's for over 10 years mainly medium duty, aka duramax etc. . I can help myself, and have no major complaints with the truck. Since I am a tech by trade and am not familar with the system it's driving me insane when it works and there is no indicator. Just looking to see how the system works for everyone else. Any and all input would be greatly appreciated.
    Last edited by ChevyFan; 01-24-2013 at 11:38 AM.

  2. #2


    Similar experience. Also when it cuts back to v4 I get a vibration that seems to be getting worse. Unfortunately my dealer can not duplicate the feel.
    With 20,000 miles I get an average of 17. I find going downhill the v4 doesn't always kick in.
    This is with meticulous upkeep, air pressure is double checked every Saturday. Oil changes and washes are religiously performed.
    Best MPG in one trip was 18.3.
    2010 Chevy Silverado Z71 ext cab.4x4
    72 Monte Carlo 350-415 hp- sold (June 2011) to pay medical bills
    79 Impala 350 4bbl 375 hp- sold (June 2011)to pay medical bills

    "If He asks you to go a mile go two"

  3. #3


    Thanks for the reply. I seem to be getting the same. I really wanted a full size, but purchased a canyon new instead (price). Now, I am not quite so sure it was a good trade. I love the truck, and have been a chevy guy all my life. having said that, I reset all of the fuel trim data, and learned data and the issues toned down. I'm not saying they are gone, But maybe for a little while anyway.
    Do you have a light that tells you when its going into v-4, i only ask cause I do not. I can however see which cylinders its cutting off. While monotoring the tech two it cuts off different cylinders on decel, cruise, etc. I have noticed that it constantly cuts them off even if you don't feel it.

  4. #4
    Sr. Mechanic 747's Avatar
    Join Date
    Nov 2011
    Jackson, TN


    From what Ive read, 17 average is pretty normal. You should be able to see when the V4 mode is active. Do you see the 4 buttons aligned vertically on the left hand side of your guages (on LS and LT)? Push the top button, and it will give you different kinds of vehicle data.
    2011 Silverado, ext cab, LT, Z71, 4X4, leather interior, color matched mirror caps & bowtie.

  5. #5


    if you have the DIC you can cycle through the buttons and one will show which mode you are in.

  6. #6


    My dic dosent have that. I only have the trip reset type dic. I dont have the buttons to the left of the steering wheel. When I cycle through it shows trip, oil reset, compass, trans temp, and mileage.
    I am going to the dealer to have remote start programmed (since I can no longer program through tech 2), i am going to ask if they can program any extra abilities.

    ---------- Post added at 05:48 PM ---------- Previous post was at 05:46 PM ----------

    Mine is a 2010 lt 5.3 6 speed flex fuel

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