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  1. #101

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    This is a great thread, im excited, looking to turn off my AFM in hope to exceed the 16.7 mpg I am getting from my 2011 5.3 z71 with 70% highway miles not hot rodding, I didnt expect the 30 mpg I get in the HHR, But I do expect better than I am getting, I wont pretend to be an expert with the AFM, I am not but I am learning more each day, In the early days when AFM was created for the caddi, they replaced motors at 20k miles regularly, slowly over time the problems have been tweeked, but clearly not resolved, It would really be nice if GM would just step up and say, we fixed this for these model years, and improved this for these model years, we would at least know the weak points to focus on, or what resulting damages over the long run could be,poor milage, oil consumption , carbon fouling, all serious issues to be playing a guessing game with. I agree GM engineers are awesome, now engineer a switch that allows the consumer to simply switch off the AFM at the choosing so we can stop sneaking around with tuners and the likes to get this done and taking the chance of voiding our vehicle coverage. AFM has the potential to be a great thing, it just isnt at the moment, at the moment it seems to be more driven out of competitive mode than out of good service mode. Currently its all about competing with the eco boost system, at any rate this is an awesome thread and I am learning alot here, this place has some really well schooled and skilled people to learn from.
    Life is short compared to history

    Rick (summitwhite11)

  2. #102

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    Quote Originally Posted by summitwhite11 View Post
    This is a great thread, im excited, looking to turn off my AFM in hope to exceed the 16.7 mpg I am getting from my 2011 5.3 z71 with 70% highway miles not hot rodding, I didnt expect the 30 mpg I get in the HHR, But I do expect better than I am getting, I wont pretend to be an expert with the AFM, I am not but I am learning more each day, In the early days when AFM was created for the caddi, they replaced motors at 20k miles regularly, slowly over time the problems have been tweeked, but clearly not resolved, It would really be nice if GM would just step up and say, we fixed this for these model years, and improved this for these model years, we would at least know the weak points to focus on, or what resulting damages over the long run could be,poor milage, oil consumption , carbon fouling, all serious issues to be playing a guessing game with. I agree GM engineers are awesome, now engineer a switch that allows the consumer to simply switch off the AFM at the choosing so we can stop sneaking around with tuners and the likes to get this done and taking the chance of voiding our vehicle coverage. AFM has the potential to be a great thing, it just isnt at the moment, at the moment it seems to be more driven out of competitive mode than out of good service mode. Currently its all about competing with the eco boost system, at any rate this is an awesome thread and I am learning alot here, this place has some really well schooled and skilled people to learn from.
    I have such a hard time thinking that GM did not know about these issues before they went into production. They put these motors through some serous testing (I have family and friends that are the guys that run these tests) before they are even approved for manufacture. I am going to talk to the guys that I know over at power train and see what they can tell me about how the tests went. I know that it is not all the motors with AFM, only a "small" percentage. But, they test enough of them, you would figure that they would have seen the issues in at least a few of them.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #103

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    There is a way GM reports failure and it's the TSB. The nice GM customer care advisor that contacted me here when I told them my dealer could not reproduce the lifter tap that effects 2007 to 2011 and is apparent in my truck. They will send me to another dealer and see if they agree the TSB should be done. If they say no and the valve train is damaged later on, it's on them. I've still got three years on my warranty. The TSB says if the noise is above acceptable vale train noise they replace all 16 lifters. Only the eight AFM lifters are a different part no#, this tells me that GM knows whatever the leak down rate or the lifter design it's self is bad. They also have TSB for oil consumption and a TSB for derivability with the trans and ECM causing a surge forward when the brake was applied. Oil consumption was a different baffle put in the motor and the surging was a firmware update.
    I live down the road from GM powertrain Tonawanda plant and have family that work there. I hear a lot of what goes on and what they know and the sometimes simple fixes. You'll be pleased to know the new family of motors fix a lot of the bugs in the last generation. It seriously didn't take much for them to get the extra hp in the new motors. Cam profile and different ECM profile and bang 40 more horse in the 5.3, they kept the hp rating on the last motor where it was because the reliability on the old motor said to at 315 would produce the greatest longevity not the greatest stoplight to stoplight time. Now with a better injector set up and better valve train the 40 hp bump is no problem.
    I am a American solder, I am a member of the finest fight force on earth, I am the bump in the night. I will defend the United states of American Against all enemies both foreign and domestic. Repent now all those who would do my nation and it's people harm; For when we come it will be too late.



    2011 GMC Sierra SLE, Z71 with 5.3 l and max tow/haul package

  4. #104

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    Quote Originally Posted by Pikey View Post
    I have such a hard time thinking that GM did not know about these issues before they went into production. They put these motors through some serous testing (I have family and friends that are the guys that run these tests) before they are even approved for manufacture. I am going to talk to the guys that I know over at power train and see what they can tell me about how the tests went. I know that it is not all the motors with AFM, only a "small" percentage. But, they test enough of them, you would figure that they would have seen the issues in at least a few of them.
    I am with you, I love my truck, I do not have oil consumption issues, with 9200 low miles on her, just getting broke in, I would like to see better mpg . I cant help but think with all the continued discussion around AFM there are no valid issues, and like you, I dont think it effects all vehicles,which is odd to me. the good news is, each year model there seems to be less of an issue.
    Life is short compared to history

    Rick (summitwhite11)

  5. #105

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    Quote Originally Posted by summitwhite11 View Post
    I am with you, I love my truck, I do not have oil consumption issues, with 9200 low miles on her, just getting broke in, I would like to see better mpg . I cant help but think with all the continued discussion around AFM there are no valid issues, and like you, I dont think it effects all vehicles,which is odd to me. the good news is, each year model there seems to be less of an issue.

    Here you go: http://www.autoserviceprofessional.c...ifters-and-DTC
    I am a American solder, I am a member of the finest fight force on earth, I am the bump in the night. I will defend the United states of American Against all enemies both foreign and domestic. Repent now all those who would do my nation and it's people harm; For when we come it will be too late.



    2011 GMC Sierra SLE, Z71 with 5.3 l and max tow/haul package

  6. #106

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    Quote Originally Posted by stchman View Post
    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.
    .
    I watch the "Trucks" show on "Powerblock TV" this morning. It was a repeat, but this time I remembered to do a followup.

    The show was about installing a supercharger on the LSx. One of the steps was to disable the AFM. they pulled the intake manifold and the valley tray, then the tray gasket. The AFM solinod is attached to the tray gasket and needs to be removed.

    However, before removing the valley tray, the oil pressure sensor connector and the AFM connector needs to be unplugged.

    The instruction manual is here: http://www.edelbrock.com/automotive_.../1000/1578.pdf

    And here are the AFM steps:

    22. Remove the factory valley tray, by unplugging the oil pressure sensor and the Active Fuel Management (AFM)
    system (if applicable). Use a 27mm wrench to remove the
    oil pressure sensor from the valley tray. Unbolt the eleven
    (11) bolts securing the valley tray using a 13mm socket.

    NOTE: Steps 23-31 outline the procedure for disabling the
    Active Fuel Management (AFM) system. If your vehicle is
    not equipped with the AFM system, proceed to Step 32.
    There are two (2) variants of the AFM valley trays:
    - Use Steps 23-27 if your solenoid assembly is secured
    to the valley tray with Torx bolts.
    - Use Steps 28-32 if your solenoid assembly is secured
    to the valley tray with rivets.
    TIP: Valley trays with AFM systems will have solenoids
    attached to the backside of the valley tray as pictured
    below. Valley trays without AFM systems will not.


    So, you can see where I'm going disconnecting the solenoid will probably disconnect AFM.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

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