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Chevy Silverado and GMC Sierra Active Fuel Management Problems

cadillac5cadillac5 Posts: 1
edited June 2015 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.

See Also: GM's Active Fuel Management and Oil Consumption 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: 8,054
    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.

  • ponch1ponch1 Posts: 1
    Hey everyone! Im new to this post, and let me share my experince with my 2008 VortecMax with everybody...I bought this truck 4 month's ago, and like some people on here I thought that this "rough shaky" idle I am experiencing would go away after a few hundres miles, I too thought it was the computer going through a "learning mode". After 1000 miles I took my truck back to the dealer, and had them try and diagnose this problem. They ended up doing a computer upgrade (crankshaft position sensor relearn). I got my truck back and it ran absolutely the same as before, I would have turned right around and gave it back to them, but I needed my truck that day, and didnt have time. I took it back a few days later, and told them to not call me until this problem was fixed correctly.... so I get a call from the dealer, and they inform me that they called general motors, and that GM is saying "this is a normal characteristic of this engine". I was dissatisfied, so I looked in my owners manual for the 1-800 number to GM customer service, and wanted some answers as to why this is normal. Let me tell you people that this was a COMPLETE waste of time for me. They wont get on technical terms with you, or connect you with someone from an engineering dept, instead they give you a mailing address to write to in detroit. I went that route, and sent a letter to them 2 MONTH'S AGO, and never received a call from them. The only thing they did for me was send out an area rep from GM to look at my truck's problem at the dealership. This clown cared more about getting home because he was tired, and told me more about his personal life etc...bla..bla., and didn't care one bit that I was dissatissfied. They tried to keep me happy by extending my warranty for free, but that does NOT fix the problem. I then wanted my money back, and was gonna hand them the keys, but I was told that I cant do that, and that I have to go through a long drown out process of contacting a lemon lawyer, and other things. I also learned that you should NEVER sign an arbitration agreement, when buying a vehicle, (which I signed accidently). All in all, I am DONE with general motors...mainly because of their terrible customer service,...I will continue to tell as many people as I possibly can to buy from someone else. I dont even care about the gm discount which I qualify for anymore, I am done!! I have been a loyal gm owner ofr years, but they really pissed me off now.... Good luck everybody.
  • natesmsnatesms Posts: 20

    Do you have the 4.10 gears in yours? I know there is a package that has the 6.0 with the 3.73's. The Max package puts in the 4.10's. I turn about 2300 RPM at 70mph. The 5.3 with 3.73s I test drove turned 1900 - 2000 at 70mph.

    I must say that aside from feeling the AFM kick on and off (my passengers don't notice it like I do, I think it has a lot to do with how closely I am paying attention to everything in my new truck), I really do like driving it around. I think if you want to tow an 8,000 pound boat comfortably you just have to accept paying the price at the pump, or pay the price on the sticker and get the diesel.

  • mule4mule4 Posts: 36
    ponch1 I was a die hard gm, ford & dodge owner. Wouldn"t look at anything different.I had all kinds of problems with a new gm car & new truck.All they would say was all the problems were normal. knowing they were lieing.I own a truck now that gets 18.5 to 19.5 on freeway 70 mpg with cruise set & depends how strong wind is.It doesn"t have AFM.It has 381 hp 6 spd. trans.It will pull a 9500# trailer like a 3/4 ton but my tk. is 1/2 ton.I had one problem with it They fixed it with no problen at all.Great service dept.Good luck with your new truck.I have had with mine
  • sknabtsknabt Posts: 14
    "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." - 1offroader

    I agree 100%.

    Don't own a 6L but I do own an '08 5.3L Sierra. Overall city/highway I'm up to 17.2 mpg. To get there I have to liberally use the cruise control. Don't do 70. Tend to set it to 65 and forget it. I even use cruise control around town when I know I'll be able to tool down the road a couple of miles.

    Even mild acceleration sets it to V8 mode. I find my foot on the petal isn't as efficient as the cruise control going up inclines and maintaining speed. On flats cruise control spends the majority of the time in V4 mode. Naturally, when going down even gentle grades cruise or no cruise you'll get great mpg in V4.

    I haven't reset the command control to see how much I get just on the highway but looking at the instant fuel economy display I'd estimate 19-21 mpg.

    The downside is around town going stoplight to stoplight it's hard to get decent gas mileage. I tend to press the petal briefly to maintain speed then drift a bit, etc. But it depends on traffic.
  • Good Lord: all these probs with the afm in these new mod has convinced me jus to put a new block in mine when she's done. I have the 99 new body z\71 4x4 and have loved every minute behind the wheel,with almost 300 thou she has been without a doubt the best truck I have ever owned.3 foot of mud or flat out like a lizzard she performs like a dream,and at a mer $2,3000.yep a new 5.3 block is in my future. :shades:
  • natesms
    I have the 3.73 gears, and 6.0L. I am not towing a huge trailer or boat and don't need the 4.10s. Yes, the Max Trailering package has the 4.10s.
  • chainlink
    Chevy has sold perhaps 100,000 Silverados with AFM and there are what, 27 posts about problems??? And several of those posts have been by the same person. Do you consider that a sign of a major problem?

    I'm sure you've got a fine truck but I don't think 27 posts is excessive considering the tiny fraction of 1% with problems, do you? If there was a vehicle out there that sold 100,000 units and there were 100 problems (0.1 %) would you not buy it?

  • I agree with 1offroader. Given the volume sold and the small number of posts I think overall most poeple are happy with their purchase. Even with all the talk about how great the Toyota's are, if you look through that forum there is gripping going on there as well. I was amazed to see there were multiple people reporting getting the motors replaced due to "loud knocking engine noise".

    I'm getting used to the AFM "kick" and don't really notice it that much anymore. I'm also averaging 12.5 in the city now, which given rounding and factoring in that is very cold and remote start has made my list of top 5 best things ever, is excatly what the window says.

    I have a 550 mile trip this weekend. I'll reset the average and let you all know what I get at highway speeds. I don't believe I have the will power to not do at least 5 over the speed limit so I expect it to be pretty crappy at 75 mph.

    Another question pertaining to fuel mileage. Does anyone know if you get worse milage when you have the 4X4 set to auto (assuming it isn't engaged all the time)? I can hear something moving when you switch it to that mode, so I'm assuming that you are turning more "stuff" and hence decreased milage.
  • mule4mule4 Posts: 36
    About the small number of posts about the problems don't mean anything. The larger number of people don't post on these forums. lots of people that have trouble with their trucks have been told it's normal & they believe it .
  • I doubt 100,000 owners are even aware of this forum. Just my .02. But I do hope its not as bad as you said.
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