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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 Steve; 01-24-2013 at 11:38 AM.

  2. #2

    Default

    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
    oldfart2413@gmail.com

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

  3. #3

    Default

    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
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    Nov 2011
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    Default

    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

    Default

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

  6. #6

    Default

    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

  7. #7

    Default

    Welcome to the club. I would buy one of the Diablo tuners and turn the afm off. People that I know that did this saw no drop in fuel mileage.
    :cool:

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
    4.10 PercisionGears w/factory locker, T/A Performance rear-end cover
    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
    B&M aluminum deep transmission pan
    Warn brush guard w/Warn 9.5 XP winch, PIAA bulbs, Line-X bedliner, AWS Black tool chest, Extang tonneau cover
    Weather Tech floor mats
    Cover-Craft seat covers
    Dash mat cover
    Formula One window tint
    One black Lab in rear seat.
    :glasses:

  8. #8

    Default

    my 2011 5.3 gets 15 to 16 city and on highway 20 and if your on a long flat road with cruse you can get 22. (3:42 rear end)

  9. #9

    Default

    I've only had my 2011 Silverado a week and have 370 miles on it but one thing I noticed right away was a sort of lag when changing throttle positions, where I noticed it a lot is when coasting in V4 and giving more throttle it tends to lag like a small hiccup then accelerates and changes to V8 mode.
    Other 5.3's with AFM I test drove had this same hiccup so I assume it's normal, I have 18" wheels on mine and did notice a truck I test drove with 20" wheels had more of a lag to it. Hadnt noticed any noises associated with the different modes.

  10. #10

    Default

    I got 18.5 last week, This week i got 13.5 Not real sure what thats about. Filled up tonight, if I get that horrible again will have to back up and punt.

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