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Chevy Silverado and GMC Sierra Active Fuel Management Problems

cadillac5cadillac5 Posts: 1
edited December 2013 in Chevrolet
There is a problem with the active fuel management systems on ALL 2007-2008 Sierras that have the 5.3L or 6.0. The 4.8L model does not have active fuel management. For the old timers out there, it is the same issue as the Cadillac V8-6-4 engine. Make no mistake, If your vehicle has active fuel management, you have a problem! GM is aware and do not have a fix for this issue.


  • What is the problem, exactly? You need to be a little more specific. I have 11,000 miles on my 6.0L Silverado and the only problem so far has been excellent fuel mileage and seamless operation.

    It IS NOT the same system as the old 8-6-4 Cadillac. They are COMPLETELY DIFFERENT in design and operation.

    Get your facts straight, then post when you have something more to say.

  • I have a problem? Thanks!!! I'll rush right down to my dealer right away and tell them: "Hey, I have a problem with my AFM", he'll say: "What's the problem"? I'll say: "I have no idea, but some dude on said everyone with AFM has a problem with their AFM".

    Whew, glad I found this thread, cuz till now, my 6.0 has been running flawlessly.
  • My 07 Has NO PROBLEMS. Which comes back to the accuser to provide viable proof instead of mindless jargon.

    I cant help but think back to the writing style which is similar to one I haven't seen till now.

    Time to get back to reading issues that are reality based from Chevy owners.
  • obyoneobyone Posts: 8,065
    Attributing intent to trolls is a very difficult issue since by its very nature to call someone a troll is to already assume an intent, that they are posting only to cause problems. So once a person is called a troll they have already been categorized by the speaker as someone with a certain intention.
  • My 2007 Vortec Max has only one problem It Runs Great and my wife thinks I love my truck more than her :)
  • What kind of fuel economy do you get with a 6.0 with active fuel management
  • yeah i second that..whats everyone gettin in terms of milage..
  • Hey I'll stand right there with you and agree with there being a problem. My 2007 New Body Silverado 6.0 liter with max trailering has been running like crap since day one. Thought it would break in and the issues would go away...not! Its been to dealer and they told me it needs more time to have the fuel cells trimmed because it is a "smart" truck...I HAVE 3000 MILES NOW and it still runs like crap. It stutters and tugs going up hills and doesnt know when to shift. Plus it has a distinctive rough idle. It has a subtle noticeable pop when AFM kicks in and it sucks to drive it. It is going back to dealer again soon but they are saying that it might take 5000-7000 miles before the brain learns my driving habits. HEY!!!!!!!!!!!!!!! I shoudlnt have to wait for that long to have a truck run correctly! THERE ARE PROBLEMS OUT THERE WITH THESE TRUCKS CAUSE I HAVE ONE ONE OF THEM! If I drive in third gear and AFM doesnt kick in then the problem is gone...rough idle still exist I say that the AFM is the culprit. GM needs to address this issue and notify dealers how to correct it. I will continue to take mine back til its fixed or lemon lawed! When you spend this kind of money you should receive a solid good running vehicle! 2 dealers are now telling me that there is nothing they can do! BULLCRAP! I have owned many chevys and this is the worst running one I have ever had! For those of you who are lucky to have a good running one, realize there are many of us out there that have bad ones! as the forums will show! :mad:
  • Just purchased 2008 Z71 Siverado 1500 5.3L 3300 miles both sensor causing engine hot error and fuel sensor back ordered, problem seems to be wide spead and cold related accordin to local dealer in Anchorage :(
  • tafidtafid Posts: 12
    I agree that something is not right. This my experience.
    When easing to a stop or after stopping and slowly rolling (by easing off brake, no throttle apply) into my garage, the engine speed will increase surging the vehicle forward. It does not matter if the engine is cold or warm, nor driving for one minute or one hour. The engine speed will increase up to ~1000 rpm or more. The engine speed will surge and slowly come down to ~600 rpm in less than 15 seconds. This problem does not occur all the time, but I can bet on it happening each time I drive.
    This condition is known and called normal (by GM) with Silverados with AFM. I tried to get someone at Chevy to see that a vehicle accelerating on its own is not right. No luck. They don't talk to you, they send customer service to deal with you instead.
    So I will need to live with the condition and hope the sudden accel does not get someone hurt.
  • tafid
    I have AFM on my 2007 Silv. w/6.0. It doesn't do anything like you describe. In fact, AFM 4 cyl. mode does not even engage at speeds less than about 15 mph. I think it is WAY premature to blame your problem on the AFM system. It could be a malfunctioning engine control module, a sticky throttle body, etc. There are many things it could be besides the AFM. I am in no way downplaying your problem, just pointing out it very well may be unrelated to AFM. Good luck solving the problem, please post when you do. So far at 13K no problems, I like my Silverado. It's not perfect, but what is? It's the best 1/2 ton truck out there now, for a while anyway, at least until the Ford and Dodge re-design in a couple years.

  • tafidtafid Posts: 12
    Thanks for the comment. I am not the one who said my sudden accel issues was caused by the active fuel management system. The company (Chevy) told me that the reaction I am getting is normal with all Silverados with AFM. I agree that there seems to be another issue, but no one will listen or acknowledge it. As I was verbally told in the beginning of my attempt to get his resolved, there is no calibration for this issue 'at this time'. So I am stuck with a vehicle not functioning properly. There are no safety concerns and therefore no urgency on their part.

  • tafid
    I don't care what the Chevy dealer is telling you, it isn't true. I don't experience any of those symptoms. Nor do most other Silverado owners. The dealer may just be trying to get out of fixing it. Don't allow that to happen, stand your ground and get it fixed.

    A vehicle surging forward unexpectedly, such as you described in your earlier post, is most certainly a safety issue and you should present it as such.

  • natesmsnatesms Posts: 20
    I recently bought a 2008 Max with the 6.0 and I have the same concerns that you posted here. I have a rough idle (it seams low to me to, 450 - 500 rpm when in gear and stopped). The RPM's bounce around a little when you are sitting at a stop light.

    I also have the same tugging issue when you go up hills. That one really bugs me, you have to give it some gas to get it to downshit to make it stop. There is also no question when AFM is kicking from 4 to 8. You feel it, even at highway speeds.

    I just got this vehicle so I'm hoping the computer learns over time, but I'm not convinced. I test drove a 5.3 version for 3 days and loved it. Didn't have any of these issues at all. Everything was smooth as could be. When my 6.0 got to the dealer, I hoped in, ran around up the highway and back and bought it because of my fantastic experience with the 5.3. Now that I have it at home I'm really starting to get concerned. Does anyone else have some insight on their experiences? I'm not jumping to conclusions yet as it only has 200 miles on it, but these things have jumped out at me compared to the 120 miles I put on that 5.3.

    Also, fuel mileage. Anyone able to get anything close to the sticker on the window? I ran 35 miles on flat road at about 60 - 70 mph and averaged 13.4...holy crap!
  • tafidtafid Posts: 12
    Thanks for the support.
    I even tried going through BBB Autoline to get help. Thought they could help mediate. But the BBB Autoline is funded via the auto industry. They say they are impartial, but.... I am trying other approaches, like this forum. Someone knows there is an issue, or that this is not NORMAL.
    BBB Autoline makes you prove there is a problem. So it is you against the auto company.
    I am a customer who is not satisfied, though GM says customer satisfaction is important to them. I'm sure.

  • natesms
    Your mileage is horrible, there is something wrong. Doing 70 mph on flat fwy. I expect 18 mpg. I have gotten as high as 18.5. No foolin, done it many times. Of course thats assuming you are not hitting the throttle hard getting on the fwy. etc. Even so, in bumper to bumper commuting traffic I get 15. The weird surging and the bad mpg may be related. Don't accept what the dealer is saying.

    As to idle, mine fluctuates a little but that doesn't bother me, it's a truck not a Benz. As long as it doesn't make me spill my beer it's not excessive. :surprise:

  • natesmsnatesms Posts: 20

    Thanks for the comments. I went out this weekend and put another 250 miles on it to bring my total up to 500. I did another 15 mile run at 65 - 70 mph and my mileage was up to 15.5. I think I'll give it another 500 miles and see where I am at, it might really just need to break in some more.

    The idle doesn't bother me, I just noticed it because my old F150 never so much as shuddered. If it was shuttering it meant yet another coil pack went out (stupid, stupid design, first thing I did with this truck is pop the hood and make sure something similar didn't exist. Looking forward to being able to park this truck in a rain storm without fear).

    I must say I do not like the AFM very much though. It is noticeable when it turns on and off. After some more research this seems to be normal and a common complaint among owners. From other things I have read it seems to be more prominent with the 6.0 than the 5.3. On one website, out of 6 reviews it was listed 6 times under the cons section, but often with a note that you get used to it. The thing that is weird to me is that I get a "surge" (acceleration) when it goes into v4 mode, the switch back into V8 mode is smoother. I would think it would be the other way around.

    I'll post my mileage again once I hit 1000 miles, and any other developments along the way. It'll probably be 2-3 weeks unless I decide to take a road trip next weekend.

  • natesmsnatesms Posts: 20

    In my limited experience with this truck I have yet to experience anything like what you are describing. I agree with 1offroader about sticking with this until you get it resolved. I'm amazed that they don't see it as a safety issue. Have your buddy call them after he gets pancaked between the bumper and a trailer as he is guiding you back...

    Keep us posted.

  • canwcanw Posts: 3
    Santaman: Yep, I've got an '08 Silverado VortecMax 6L that I bought in Aug. 07 with the same issue. Dealer says everything runs up to the computer spec so it is "just the nature of the beast." When I got nowhere with the dealer, I went to GM and their tech people say the same thing; "the rough idle I experience is normal for that vehicle." Like you, I didn't notice this issue until about 200 miles on the odometer and my name was already on the bank loan. Too bad for me I guess. And yes, the AFM delivers about 13.5 mpg on my truck too. I'm sure that doesn't help GM's fleet average.
  • All
    I do not understand where all the lousy mpg is coming from. I get an honest 18 on the fwy. at 70 mph, in cruise control. Maybe that is the key, having it on cruise control.

    As to the afm, I have had a friend try to tell me when he thinks it goes from v8 to v4 while riding in the passenger seat, he can't do it. I can tell, just barely, if I am driving because I have a foot on the throttle and it is just barely noticeable if I am concentrating on it. Otherwise not.

    Genuinely sorry for your problems, but do not let the dealer tell you that surging is not a safety issue, it most assuredly is a safety issue. Get it fixed before someone gets hurt.

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