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Chevy Silverado and GMC Sierra Active Fuel Management Problems



  • msw007msw007 Posts: 21
    I agree with churchy25. I could see replacing some minor things under 83000 miles but to replace an entire motor??

    This is a GM design flaw and they are hiding behind the warranty issue. I have never argued the fact that $3000 for the motor was not a good deal. I just want GM to admit they have a bad design flaw and they have to take care of it. I'm sure GM is betting on the come that these motors will start failing after 100K miles and then they can say too bad so sad to the consumer.

    The problem is these motors are failing at an alarming rate at 50K miles with 75K-85K being the sweet spot for failure. So cars my age are starting to get to that mileage and pretty soon there are going to be a whole lot of pissed off consumers out there.

    If you have your heart set on a GM vehicle (2007 and newer) with this motor then I strongly urge you to purchase the extended warranty.
  • kmt3kmt3 Posts: 2
    My2011 sierra 5.3 afm gets 16-17mpg around town or has a hard time staying in 4cly mode even at 45mph.several times its run 55+mph and had no problem staying in 4cyl mode also showed very good mpg on instant readout.sometimes aroundtown it will do same, but get it in v8mode it will not return to state of operation as before.been to dealer and had it checked out-everything ok.ive heard rumors of these trucks running 6o+mph on 4cyls and 20+mpg also heard about a lot like starting to think some of these have an inherent problem, with software or whatever. Id like to hear from others about performance/fixes etc.
  • msw007msw007 Posts: 21
    Well we have the new remanufactured motor installed.
    I spoke with the mechanic at the dealership and asked what exactly happened and if this was normal?
    He told me the rings on the piston were worn and caused the leak by which fouled the plug. The cylinder wall were scarred and the other cylinders were starting to look worn.
    He just shrugged his shoulders when I asked him if this was normal (that kind of says it all right there).
    I know Black Bear Performance offers a tune solution to turn the AFM off. I guess they started to offer this due to the rash of complaints and problems that have been associated with this.
    I have sent letters off to GM's upper management pleading my case. I'm not expecting much but it doesn't hurt to try.
  • chuck1chuck1 Posts: 1,405
    There is a company called Range Technology that sells "black boxes". They sell one that will either keep you in 4 cylinder mode longer or one that keeps it in V8 mode only. They plug in to your diagnostic port AND LEAVES NO TRACE ON THE ECM.
  • msw007msw007 Posts: 21
    So I received a phone call from GM Corporate (my letters got through). I have spoke with him several times and as of now GM is holding firm on the 50/50. They say because I accepted the deal there's nothing else they can do? I reminded him I accepted the deal because I had a useless car and it had to be fixed (holding a gun to my head).
    I told him right up front I'm not looking to get off without paying anything. I understand the car was out of warranty but the fact of the matter is the engine failed under 100K miles.
    He said there were a few more upper management people he could plead my case to. So I don't know if he's blowing smoke up my a** or he's being truthful. We'll see.
  • chuck1chuck1 Posts: 1,405
    Be glad you got a motor at 50% off and move on. We have seen your posts just like this one on several other boards.
  • jboehmjboehm Posts: 44
    Reading the boards it looks like I am just starting this process, but thought I would add my story as well. I have a 2009 Silverado with 41k miles on it. I noticed over the winter that my idle had gotten pretty rough (to the point that the check engine light came on a couple of times) so I did some research and found issues with the #1 and #7 plugs becoming fouled. Figured the next time I did an oil change I would mention it and see what the dealership wanted to do. Over this last weekend I was driving home when I heard some major clicking noises coming from the engine. Since I needed an oil change anyway I dropped it off at the dealership and mentioned the rough idle and clicking noises. The end result was that the #1 and #7 plugs were cracked so they replaced that and also put on a redesigned cover. I did buy a GM extended warranty just before the 3/36 expired (glad I did) but have to be concerned about where this may lead me to. Especially when I read that motors are being replaced at 80k - 85k miles.

    I let the oil life monitor tell me when the oil needs to be changed but since I bought the truck new I have done generally 9 months between changes but this last time it was barely 6. When I mentioned that they also want me now to come back every 1k miles to do a consumption test.

    Love the truck, have a warranty to cover issues but have to deal with the hassles (and the possibility of a engine replacement right after the extended expires).
  • jswain2jswain2 Posts: 16
    I traded my truck in tonight. Won't say what brand, it doesn't matter. It's not gm.

    I kept hearing lifter tick and spark knock which had gotten a little worse and I was tired of worrying about the lifters and hoping it wouldn't start burning oil. I'd had enough. I hope I have good luck with this one, and I hope all the 5.3 owners have good luck. I, personally, would not recommend buying a gm vehicle with afm. Too many reports of issues, too much worry. But if you do get one or have one, I wish the best for you. Here's to all of us staying out of the service department for a long time. Other than maybe a free oil change.
  • I personally think you made a wise decision. Best of luck with your new ride.
  • mr_pinkmr_pink Posts: 3
    I bought an 07' GMC Vortecmax 6.0 SLE a year and a half ago with 60,000 miles on it. I pulled out of my driveway this winter, and you know "what" hit the fan. To make a very long and depressing story short. I have a misfire on cylinder #1 which shut off my stabilitrak and traction control, also my oil manifold needs replaced. I took it to a dealership, they quoted me 2100$ for just the left bank repair, and 3400$ for both banks, all gaskets,bolts,manifold etc.... I still owe 15k on it and am sort of stuck paying for a rolling paperweight. I have no warranty since it now has 112k miles on it and its 6 years old. God bless GM for making vehicles last just over a 100k so the unexpected blue collar worker has a hard time finding a ride to and from work, my next vehicle will not be a GM made product. :lemon: My GMC
  • mr_pinkmr_pink Posts: 3
    To all the Idiots on the first thread that were saying " My 6.0 max runs flawlessly." and " My wife thinks I love my truck more than her." I bet now that there has been time on you're trucks it isn't running so well. My 07 max has 112k and the AFM failed all the way across the board.
  • jswain2jswain2 Posts: 16
    Thanks, bro. I gotta say it was quite a relief getting shed of the afm. I'm loving the new truck right now, but I have less than 1k miles. I hope it gives me good service. It's all 8, all the time. And I like it that way. I owe $12,500 after trade in and rebates and some dealer wrangling. But, for now, I'm under warranty and don't have that sickening feeling of impending mechanical failure. Again, good luck to all with afm issues. I have been there. Geez I hope I never have to talk to another service manager.
  • dmm8dmm8 Posts: 1
    I really wish someone had warned me about the AFM engine before we bought our 2010 Silverado. That truck has been amazing up until the past few months. We are currently on our 3rd oil consumption test and they still haven't officially diagnosed what the issue is. I've been reading a lot lately about the AFM engines burning through oil or the oil pumps going out, which would make sense. Had I known about these problems before we bought it....we would have gotten a different engine. The whole point to having a new vehicle, is to have a reliable vehicle. Now I'm afraid of my truck dying every time I stop because the oil pressure drops so low. :(
  • gmcustsvcgmcustsvc Posts: 4,055

    Please keep us updated on your oil consumption test and diagnosis. If there is anything we can do please let us know.


    Amber N.
    GM Customer Care
  • chuck1chuck1 Posts: 1,405
    These motors (good or bad) run with very little oil pressure. IT'S NOT ONLY YOUR TRUCK. THEY ARE ALL THIS WAY.

    If you wish to turn off the AFM-invest $200.00

    I know you shouldn't have to spend to do this, but the dealer will not turn off the AFM for you.
  • cmezumcmezum Posts: 1
    junked the afm!
    installed mild street cam, texas speed push rods, new lifters, mild ported the heads, valve job, and dual springs installed, ls7 valley tray, long tubes and y pipe, intake, and tune. 260whp stock
    estimating 70-90 whp increase. going to strap it to the dyno today for the tune and final numbers.
    Would still be stock if GM had designed it better.
  • chuck1chuck1 Posts: 1,405
    With the range device owners are reporting oil consumpion issues being much less with the V8 only range device.
  • chuck1chuck1 Posts: 1,405
    How does rebuilding the motor to different specs affect the emissions?
  • jframejframe Posts: 5
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