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Chevy Silverado and GMC Sierra Active Fuel Management Problems

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Comments

  • string2string2 Posts: 71
    Hey Chuck,
    Do you know if there is an adjustment for the gas pedal?
    You are also assuming that the truck doesn't have a problem. I have driven both ways on the same stretch of highway (no wind), over inflated the tires, upgraded to higher octane gas and no extra weight or passengers. If Chevrolet didn't show on the dashboard when the AFM is changing from 8 to 4 cylinders you couldn't pinpoint why the gas mileage is so bad because it is not activating a trouble code. Why cover up the fact that it is not working?? On the highway I am getting about one more mile per gallon that city driving 15 MPG). That's probably because of not stopping and accelerating
  • chuck1chuck1 Posts: 1,405
    I don't know if there is an adjustment. I will tell you on a recent trip form Salt Lake City, Utah to the Nevada state line I filled up and it was right at 20mpg. This included three mountain passes at over 6,000 feet in elevation. Then, from the Nevada State Line home to So. Cal the mpg was 18 1/2. (I drove a little faster across the desert).

    I have a 2011-5.3 Crew Cab with 2WD. I also have a tonneau cover which may or may not gain mpg.

    I am not downplaying your problem. All I am am saying at highway speeds the AFM will not come much on unless your going downhill. The truck weighs close to 6,000 pounds and it takes a little to move it along.

    Good luck on your issue.
  • gmcustsvcgmcustsvc Posts: 4,100
    string2,

    Sorry to hear about the problems with your vehicle. Since you have spoken with customer assistance, could you please send us your case number? We would like to look further into your situation.

    Thank you,
    Caron, GM Customer Service
  • string2string2 Posts: 71
    Caron, thank you for responding to my post.
    My service #: 71983951187
    I hope you have better luck than I am having trying to convience someone that I really do have a problem. Since my last post, I took the truck back to
    Ron Craft Chevrolet in Baytown, Texas. Mr Foust was a little more helpful on this visit and I am hopeful he will follow thru and help me. The following is that part of my documentation of the problem:
    10/18/2011 Afternoon - I drove over to Ron Craft Chevrolet and sat down to talk with Paul Foust. I explained that I was still having the same problem. He contacted someone referred to as a 2nd level Tech. at GM. He was referred to a document that he had not seen before (Document ID: 1995547). It describes how the AFM system works and some possible reasons the truck could be having this problem.
    Together, we did a test drive in the truck and used his hand held plug in computer diagnostic tool. He could see that the engine was not dropping back to 4 cylinders at highway speed except when there was a decline in the highway or when removing my foot from the gas pedal. His diagnostic tool also showed there was some sort of problem with the MAP and possibly the acceleration. He was unsure about how to address the problem. He ask me to call him on Friday the 21st.
  • string2string2 Posts: 71
    Caron,
    This is a follow up to my reply back to you yesterday. what I really need is a GM engineer, but it's next to impossible to get that level of service, for some reason?? If nobody knows how to correct the problem, why not????

    10/21/2011 11:15 AM - I called Mr. Foust at Ron Craft and left message. He Called me back about 15 minutes later. He said he had driven another truck on the lot, and it had a similar problem. He hasn’t been able to talk to anyone about how to correct it. Said he would call me back sometime next week. This has been dragging out like this for almost two months now.
  • gmcustsvcgmcustsvc Posts: 4,100
    string2,
    I have looked into your case and they are working on it. Thank you for your patience, I understand this is frustrating. I apologize for the inconvenience. Your dealer is researching this further with Technical Assistance. I recommend continuing to work with your dealer.
    Christina
    GM Customer Service
  • Christina, Thank you very much for your assistance in trying to resolve this problem. I left my truck at the dealer for your GM engineer to check it out. To my disappointment and surprise, he said it was working okay.???? This I do not believe! It defies common sense. Why build and advertise the GM “ Active Fuel Management” system when it doesn’t work at the normal highway speed limit of 70 MPH (changing from 8 to 4 cylinders), at the very time it is most needed to get its highway fuel economy? I don’t think working at 66 MPH or less, for one minute, qualifies for working “okay”! Besides, who would want to take a chance on driving at LESS THAN 66 MPH on the open road and possibly get ran over by a fast moving truck. Also, it only worked for ONE MINUTE, and that was on a slight downhill grade (the rest of the time it wouldn’t be working at all). Please read the paragraph on page 9-40 of the 2011 Chevrolet Silverado Owner’s Manual, explaining the operation of the “Active Fuel Management” Driving and Operation. If this isn't double speak, then I don't know what is?
    Thanks again Christina for your attempt to help, but it looks like I won't be getting any assistance from GM. There really is a problem!
  • Im in the Houston,Tx area. Does anyone know of a GM dealer who knows something about the 6% throttle or pedal setting on 2011 Silverado 5.3 engine, and how it relates to the activation (on/off) of the Active Fuel Management system. The dealers I have spoken with, know very little about it.
  • AT 6% throttle or less the AFM kicks in - what are you trying to do or determine?

    The truck is drive by wire - so the trucks computer would in all likelihood control that function.
  • String2,

    Some dealerships I located in the Houston area include:

    David Taylor Cadillac Buick GMC (Phone 713.777.7151)
    Beck & Masten Buick-GMC Truck Gulf Freeway (Phone 713.947.4111)
    Demontrond Automotive Group, Inc. (Phone 281.872.7200)
    West Point Buick GMC (Phone 281.579.4300)

    If these aren't able to assist, the following link should help you find more dealerships in your area: http://www.gm.com/vehicles/dealerLocator.html#

    Hope this helps,
    Sarah
    GM Customer Service
  • My AFM 2011 5.3 Silverado (8 to 4 cylinders) acts as though it's right at the verge of going into 4 cylinder mode at steady highway speed, but will only go there for maybe a second or two (infrequently) on level ground. Its like it just needs a small adjustment (somewhere) to make it stay in 4 cylinder mode. I know it won't work at 70+ MPH, but this is at 55-60 MPH. I've taken it to the dealers, but they can't find any trouble codes to tell them what to do. The dealers I have spoken with don't seem to know much about the AFM. If it doesn't show a trouble code, they don't know how (or have the time) to trace the problem. I'm just grasping at straws, the throttle may or may not even be the problem. If anyone is familiar with this problem, please let me know.
  • Thank you Sarah, for the phone numbers from the dealer phone book. What I really need is a dealer, that you know for a fact, has delt with this particular problem and knows how to troubleshoot it without a trouble code. The ones that I have spoken with tell me to "bring it in" but without a trouble code, it's not likely they will be able to find the problem.
  • String2,

    I apologize for a poor response on my part – thank you for clarifying what you need. If you would be so kind as to send us an email that contains this information, as well as your vehicle’s VIN, we can ask our Technical Assistance Center for more information in regards to the AFM question you are posing.

    Again, I apologize for my earlier poor response and look forward to hearing from you.

    Best,
    Sarah
    GM Customer Service
  • Purchased: 7/21/11 new at Ron Craft Chevrolet-Cadillac Dealer 4114 Hwy 10east Baytown, Texas 77521 Ph: (281) 421-3800 Service Mgr. Paul Foust email: paul.foust@roncraftautos.com

    This Truck is a 2011 Chevrolet Silverado Crew Cab, Engine: Vortec 5.3L V8 w/Active Fuel Management (AFM), Rear Axle 3.42 ratio, VIN# 3GCPCSEO3BG252186 (EPA Tested these vehicles) Their Average estimated fuel economy average was:
    CITY 15 mpg HIGHWAY 21 mpg (city is correct- Hwy 16 MPG, AFM has problem not going to 4 cylinder mode at hwy. speed, about 70 MPH (please see my prior posts)
    This fuel economy is advertised and touted openly by all the sales people at the different dealerships I contacted, including Ron Craft Chevrolet before I bought the truck.

    9/6/2011 - Called Chevrolet manufacturer 1 866 790-5700 x 21162 BECKY . She gave me a service #: 71983951187 -

    11/2/2011 Gm engineer finally looked at my truck this, as I previously posted.

    11/2/2011 Mr. Foust called for me to bring my truck to let the engineer look at it. I left it at Ron Craft about 9:30 and picked it up about 3:00 PM. Mr. Foust said the engineer checked the truck and they took it for a test drive. Mr. Foust said they could not get the AFM to change from 8 to 4 cylinders at the normal “open road speed limit” of 70 MPH, but they did get it to stay in 4 cylinder mode once, for one minute at 66 MPH . And the location where they were able to achieve that was on a very long and slight decline of the Hwy. on I 10 east near FM 146, close to Mt. Belview. To my disappointment and surprise, he said it was working okay.???? This I do not believe! It defies common sense. Why would GM build and advertise their “ Active Fuel Management” system when it doesn’t work at the normal highway speed limit of 70 MPH, at the very time it is most needed to get its highway fuel economy? I don’t think working at 66 MPH or less, for one minute, qualifies for working “okay”! Besides, who would want to take a chance on driving at LESS THAN 66 MPH on the open road and possibly get ran over by a fast moving truck. Also, it only worked for ONE MINUTE, and that was on a slight downhill grade (most of the time it wouldn’t be working at all). Please read the brief paragraph from the 2011 Chevrolet Silverado Owner’s Manual, p. 9-40, explaining the operation of the “Active Fuel Management” Driving and Operation. Is this not doublespeak, or what?
  • Purchased: 7/21/11 new at Ron Craft Chevrolet-Cadillac Dealer 4114 Hwy 10east Baytown, Texas 77521 Ph: (281) 421-3800 Service Mgr. Paul Foust email: paul.foust@roncraftautos.com

    This Truck is a 2011 Chevrolet Silverado Crew Cab, Engine: Vortec 5.3L V8 w/Active Fuel Management (AFM), Rear Axle 3.42 ratio, VIN# 3GCPCSEO3BG252186 (EPA Tested these vehicles) Their Average estimated fuel economy average was:
    CITY 15 mpg HIGHWAY 21 mpg (city is correct- Hwy 16 MPG, AFM has problem not going to 4 cylinder mode at hwy. speed, about 70 MPH (please see my prior posts)
    The AFM and its fuel economy are advertised and touted openly by all the sales people at the different dealerships I contacted, including Ron Craft Chevrolet before I bought the truck.

    9/6/2011 - Called Chevrolet manufacturer 1 866 790-5700 x 21162 BECKY . She gave me a service #: 71983951187 -

    11/2/2011 Gm engineer finally looked at my truck this, as I previously posted.

    11/2/2011 Mr. Foust called for me to bring my truck to let the engineer look at it. I left it at Ron Craft about 9:30 and picked it up about 3:00 PM. Mr. Foust said the engineer checked the truck and they took it for a test drive. Mr. Foust said they could not get the AFM to change from 8 to 4 cylinders at the normal “open road speed limit” of 70 MPH, but they did get it to stay in 4 cylinder mode once, for one minute at 66 MPH . And the location where they were able to achieve that was on a very long and slight decline of the Hwy. on I 10 east near FM 146, close to Mt. Belview. To my disappointment and surprise, he said it was working okay.???? This I do not believe! It defies common sense. Why would GM build and advertise their “ Active Fuel Management” system when it doesn’t work at the normal highway speed limit of 70 MPH, at the very time it is most needed to get its highway fuel economy? I don’t think working at 66 MPH or less, for one minute, qualifies for working “okay”! Besides, who would want to take a chance on driving at LESS THAN 66 MPH on the open road and possibly get ran over by a fast moving truck. Also, it only worked for ONE MINUTE, and that was on a slight downhill grade (most of the time it wouldn’t be working at all). Please read the brief paragraph from the 2011 Chevrolet Silverado Owner’s Manual, p. 9-40, explaining the operation of the “Active Fuel Management” Driving and Operation. Is this not doublespeak, or what?

    I have read that if the accelerator/throttle is more than 6%, the engine will not drop back to 4 cylinder mode.
    My AFM 2011 5.3 Silverado (8 to 4 cylinders) acts as though it's right at the verge of going into 4 cylinder mode at steady highway speed, but will only go there for maybe a second or two (infrequently) on level ground. Its like it just needs a small adjustment (somewhere) to make it stay in 4 cylinder mode. I know it won't work at 70+ MPH, but this is at 55-60 MPH. I've taken it to the dealers, but they can't find any trouble codes to tell them what to do. The dealers I have spoken with don't seem to know much about the AFM. If it doesn't show a trouble code, they don't know how (or have the time) to trace the problem. I'm just grasping at straws, the throttle may or may not even be the problem. If anyone is familiar with this problem, please let me know
  • chuck1chuck1 Posts: 1,405
    edited November 2011
    The salespeople at the dealership oversell this feature. My AFM will not come on at 65 to 70mph. On slight downhill it does come on.

    MY average mpg (5.3-Crewcab) city is no more than 15 - usually less. The truck does get close to 20mpg highway if you keep it at 65mph and below and no head wind. 6% throttle is not very much - it takes more than that to move a 5,500 pound truck down the freeway.

    The AFM is highly misunderstood by both salespeople and the owners.

    I suggest renting another truck. It will probably be the same way. It's one thing to say it doesn't work correctly, do you have anything to compare it to?
  • string2string2 Posts: 71
    edited November 2011
    No I don't have anything to compare it to, other than what other owners of this type truck have told me when I'm at the gas stations. Some say they get 22-23 MPG. Also, the 2011 Silverado Owner's Manual explaination on page 9-40. And of course, what the new vehicle sticker showed when I bought it - average 15 City 21 Highway. What's really bad is, my nephew has a 2005 Silverado 5.3 crewcab WITHOUT (he says) Active Fuel Management. He swears he gets 22 miles per gallon. All the other trucks weigh the same as ours. It may be, you and I have a couple of lemons. I hope that's it. If not, we're all being deceived.
    It seems like GM could come up with an (approved) slightly modified ECM computer program that could be used in cases like ours. When they can't find a way to make them work the way the Owner's Manual describes. Most people drive faster than 45 - 55 MPH. (mine will only stay in V4 mode for short distances at 40 MPH) I don't understand the restriction? It's like punishing you for buying one of them.
  • chuck1chuck1 Posts: 1,405
    edited November 2011
    String,
    Honestly -I do not work for GM. There is a lot of misunderstanding regarding these trucks. There is NO WAY anyone is getting 22-23mpg with these trucks. These things weigh 5,500 pounds - it ain't gonna happen. Do a google search on the Ford F150s with the ECOTEC, even they are not getting that type of mpg.

    If your AFM is coming on going down hills - it's working. If it's not, then there is something wrong.

    I averaged 20mpg from Salt Lake City, UT to Mesquite, NV recently, and that was over three different 6,000 foot mountain passes. That's the best one can hope for.

    It always amazes me at the mpg claims made on the Internet. FYI-it happens on all forums for all makes. I don't know it must give some guys a rush to "stretch" the truth about the mpg.

    Please, if this concerns you and makes you unhappy, rent another truck and prove it to yourself. It's a truck and it isn't going to get stellar mpg regardless of what the dealers salesman told you, what others SAY they are getting, OR EVEN what the owner's manual says.

    If you driving a truck and not using it for towing, hauling - if it's just a grocery getter and your concerned about mpg, I am sorry you bought the wrong vehicle.

    Good luck - I wish you well.
  • string2string2 Posts: 71
    edited November 2011
    Maybe you do know more about these trucks than anyone else, including the writers of the 2011 Silverado Owners Manual and the EPA miles per gallon estimators. It's hard for me, though, to let the dealer sales people off the hook that easy. They represent GM. If you can't believe them, what do you do? Order direct from the factory? I don't need a truck all the time. Sometimes I need to pull an RV a couple hundred miles or haul some building material short distances. I bought the truck because it was advertised to get good gas mileage and would serve my needs to haul when necessary and use for transportation. I would then get rid of my old car. It would then serve both purposes. I'm sorry I bought the wrong vehicle too. You should be very satisfied with your truck if you are getting 20 MPG in the mountains, wow!. You must have one that works as it's should. You might not like it as much if your were getting 15.5 - 16 MPG on flat hwy (empty). With all your propaganda, are you sure you don't work for Chevrolet?
  • chuck1chuck1 Posts: 1,405
    edited November 2011
    "I don't need a truck all the time."

    15mpg is about right at 75 mph.

    If per your own words your using it for family transportation and not towing and hauling on a regular basis-you indeed bought the wrong vehicle.

    You would have been better off buying a Malibu and renting a truck for your occasional utility needs.
  • Thanks for all your, really knowlegable, advice.

    I'm glad you got one of the trucks with the AFM working correctly and gets good gas mileage. Consider yourself lucky!

    Take Care
  • Some 2011 Silverado 5.3 engine owners don't know it, but you can see if your Active Fuel Management is working while you are driving. It's on your Instant Fuel economy gauge. You will see it switch back and forth from V8 to V4. It will always go into V4 when the road grade is declining or you are slowing to stop. You aren't using much gas then anyway. It is supposed to be in V4 when cruising at a normal steady highway speed (unless you put it under more load like going uphill). The explaination is on page 9-40 of your owners manual.
    Apparently, some owners don't realize that their poor gas mileage, at normal highway speed (around 70 MPH) is because the AFM system is not working as advertised by GM and their sales people. If you are not getting the gas mileage you expected, that's probably the reason. The hidden surprise is, THERE IS NO FIX, according to the GM engineer who looked at my problem. When you test drive one of these, be sure and check to see if it's working properly. Apparently some do, and some do not. And most of the sales people don't really understand how and when it works. They will tell you anything to get you to buy it. BE CAREFUL and verify what you are told. Talk to the mechanics, if you can.
  • donl1donl1 Posts: 109
    I have a 2009 Crew Cab LTZ 4X4 with the 5.3 and AFM. You can use the DIC to watch it go from 8 to 4 cylinders and I can guarantee it doesn't spend much time in the 4 cylinder mode. That being said I'm satisfied with the overall mileage. In the summer it's usually in the 18 mpg area. The best ever was an even 21 driving 65-70 on flat ground with no AC. A two and a half ton vehicle with the aerodynamics of a refrigerator is never going to be a mileage queen...I don't care whose logo is on the tailgate. I see the 4 cylinder mode going down hill or feathering the throttle on the level around the 60 mph range. If it only needed a 4 cylinder motor for everyday driving that's what they would have put in it. But in the real world it needs a real motor.
  • chuck1chuck1 Posts: 1,405
    edited November 2011
    I run very short trips in mine-mostly 2 1/2 miles. I get between 13 and 14. On a 80 miles round trip the other night I got 17.5mpg. The mpg is right where I would expect it. The 22 0r 23mpg some people SAY they are getting is a fairy tale.

    You don't buy these for mpg. You buy them for utility. If you don't need the utility, stick with a crossover or sedan, there are many excellent choices in both types.

    I tow a travel trailer with mine-that's why I bought the truck.

    Once you drive over 70mph-you are NOT GOING to see the 4cylinder mode come on.

    I think some on this board were "SOLD" the truck rather than buying it by choice and regret the less than stellar gas mpg once the "ownership experience" set in. Now, they are putting the blame on GM instead of squarely on themselves.
  • Their sales pitch is that they do serve the purpose of two motors. The "real motor", eight cylinders when you want or need it, and four cylinders when cruising on level highway. If the 4 cylinder mode of the engine was never to be useful for this truck, why go to the trouble of building it? Besides, if you don't need or want 4 cylinders, why spend the extra money to buy it?
  • chuck1chuck1 Posts: 1,405
    String,
    Obviously, you had some major twisting or misrepresentation of what the truck is designed to do. You were sold something you shouldn't have purchased. It's not GM's fault.
  • The dealers and their sales people DO represent General Motors!

    If you bought a computer from an HP dealer and it was represented to have 7 GHz. When you fired it up and saw it only had 5 GHz. Don't you think HP or their representatives should make it right. Or, should you just say, it's all my fault, I shouldn't have bought it anyway, that's way too much capacity for me. OH, and by the way, I want you to keep the extra money you charged me for it! I should have known better. Thanks for the time you took to sell it to me.
  • chuck1chuck1 Posts: 1,405
    First of all, the dealers that sell GM cars are independent businessmen. I really don't think it's realistic to expect GM to be accountable for everything a sales person says in the sales process. If you would have come on this board before your purchase, I would have been the first one to tell you about the REAL WORLD fuel consumption. ALL OF US on this board would have helped you.

    As it stands you have one of the worst case of buyer's remorse/regret I have seen.

    GM is not going to write a separate software program (even if it's possible) just for you because you bought too much vehicle for your needs.

    Move on...I know I am.
  • Thanks for all your GM biased advice.

    I see you have posted here over 1500 times.

    I am moving on....I'm glad to see you will be too.
  • chuck1chuck1 Posts: 1,405
    I see you have posted here over 1500 times.

    Been a member many, many years.
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