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Comments
I would offer to establish a Service Request, but see that you used kilometers as your unit of measure; I'm guessing you're in Canada? If so, you could contact GM of Canada at 800-263-3777 (Hours: M-F 7:30am - 11:30pm, Sat 7:30am - 6:00 EST). I am not sure what the outcome of getting connected with them would be, but I do know that it would at least continue to document your concern with the AFM performance.
Regards,
Sarah
GM Customer Service
I'm sorry to see that you are having this noise concern with your new GMC. If we can follow up with your dealership on this for you, please send the following information to socialmedia@gm.com: your name/Edmunds username, phone and address, the last 8 of your VIN and current mileage, and the name of your involved dealership along with any recent/upcoming appointment details.
Kind regards,
Sarah
GM Customer Service
I understand that you're frustrated, and hadn't realized you've already spoken with customer service. Do you have a case number (71-**********)?
Best,
Sarah
GM Customer Service
Do you feel that the noise has progressed since your case was closed (I have it being closed in August of last year)?
Best,
Sarah
GM Customer Service
Well, was I in for a surprise- I took two 300 mile round trips (all highway at 70-73 mph) in the first couple weeks I owned the truck and got exactly the same each time- 14.6 mpg (hand calculated). To say I am disappointed isn't even close to how I feel. I spent $35,000 on a truck (for the next 6 years) that gets poorer gas mileage than the 10 year old truck that I traded in (and was paid for for the last 5 years).
I have done a lot of reading/research, and I too am convinced that these AFMs are all over the board on these trucks. Mine only goes into 4cyl. mode if I am going downhill or decelerating- never at speed on the highway. Or I should say, not until the other day. I towed my '55 Chevy to a shop and dropped it off, and I took the backroads to get home. I had it in tow/haul mode both ways, as the car trailer probably weighs 1800 lbs. I was traveling a somewhat hilly road at 45 mph, and low and behold the AFM is going into 4 cyl. mode! I slowly gave it some throttle, and it stayed in 4cyl. mode! For longer and farther than it has ever been before! Why didn't I think of that sooner? I should just tow an empty 1800 lb. trailer behind me to get maximum fuel economy! Or drive around in 4-wheel drive like alstairs. What a joke.
I complained to the dealer about the poor gas mileage (previous to the AFM episode) and in a nutshell they won't even look at the truck until the 1st oil change at 6000 miles. So at this rate, I'm thinking that if things don't improve much I'll sell the truck at the end of 3yrs./36,000 miles, and meanwhile pay the extra $800-1000 a year more than if I was getting 18 or 19 miles per gallon like I thought/hoped I would.
Unhappy Silverado owner.
Your problems and mine are exactly the same. I had an old 95 Silverado that ran good with the 5.7 engine. It got 16 1/2 MPG average and had been paid for years ago. I now get about 15 in town 16 (pure flat highway) 5.3 w/3.42 rear end. It won't go into v4 mode above about 62 MPH unless going downhill or slowing to stop. Have you read the owner's manual that explains how the AFM engine is supposed to work? I wonder how long it took to make that up? In all fairness though, I have heard that some of them do work right!
I have only found a few posts where guys have said that their mpg actually improved wth added miles, and none of those increases have been very dramatic. I can't hardly believe, new or not, that this truck can't even get on the highway what they say the low end city mpg should be. Pathetic.
The reason your owners manual says nothing about a "break in" period is that it needs no special treatment when you drive it off the lot. Though anybody is a fool to drive a new motor hard.
BTW-22 to 27 mpg is beyond the capability of the truck. I got 12 mpg around town in my new Silverado. After about 10,000 miles that improved to 14 mpg.
I am curious as to why you bought your truck. Do you have towing or hauling to do?
Sorry Chuck, but that is a blanket statement that is just plain false. Maybe it's true for you, but the last two Chevy trucks I had, a 2002 and a 1998, never changed much since day one. Same can be said for all of the Fords I had before that. In fact, my 2002 got 16.25 mpg the first year or two I had it, and never got better than 15.75 any of the 8 years after that.
The point of my 22-27 mpg statement was, how do you explain the 18-20.5 mpg a lot of trucks are getting being driven off the lot if they have to be "broken in"? How much room for improvement is there to be had if what you say is true? I maintain that there is no way in hell I'll ever see 20 mpg in this truck if it's only getting 14.6 now.
I am a building contractor and I bought the truck because my 2002 had too many miles on it and would need some repairs done if I were to keep it. The claims of the great mpg prompted me to buy a new 2012 instead of looking at used 2007 and 2008 models where the owners were telling me they were getting 17-18 mpg. I figured I would get better than that with a new truck. So much for that theory. I never would have spent $35,000 on a new truck when I would have to pay more each month for gas than I was with my 10 year old truck. I would have just paid $17,000 for the 2008 I was looking at that got 17 mpg and been satisfied, had I seen this coming.
All motors and transmissions are identical when produced. (5.3/6 speed transmission-2WD).
If you haven't looked at your instant fuel economy guage when AFM kicks into v4, the miles per gal. jumps 6 to 10 mpg. The problem is getting it to kick in at normal hwy driving speed. By the way, if the AFM doesn't kick in at hwy driving speed, it is not designed to trip a trouble code unless there is something else also wrong with it. Because there is no trouble code is the reason the mechanics keep telling us that "it is working normal". They only know to fix what the computer shows them is wrong.
I drive the truck like an old lady. But the engine started burning oil like nobody's business after the first 50,000 miles. I have not been able to use it properly for the past 12 months as it has been back and forth to the dealer
I was allowed to speak to one of their engineers who was a specialist concerning this problem. He said he could see that there was a drag on the motor. He questioned the computer program designer to see if an engine Calibration change would help with this problem. What he explained to me was this: If the engine is calibrated to operate in V4 at the normal highway speed limit of 70 MPH, the catalytic converter would not stay hot enough to maintain the correct exhaust emissions to satisfy EPA. Question: How are they allowed to get away with advertising their AFM as a fuel saving feature if it is not designed to work on flat highway with cruise control on and driving the normal 70 MPH speed limit. If they all have the same drag on the engine and all work just like mine, then it seems like the average EPA sticker on the window should read 15 City and 16 Highway / AC on (about the same in cold weather).
Seems still to be some conflicting information. After numerous 600 mile road trips, my AFM works at 70mph and nets me 20mpg on the highway. HOWEVER, it will not work ABOVE 70mph.
I have not had any check engine lights or anything to come on to suggest this isn't normal.
Apparently, good or bad, not all trucks operate like yours.
I have taken numerous (5 to 6) trips from So. Cal to Salt Lake City, UT. documenting this fact.
I have not had any check engine lights or anything to come on to suggest this isn't normal.
Apparently, good or bad, not all trucks operate like yours.
=====================================================
Hi Chuck,
Without a doubt, i'm stuck with a bad truck or engine. I'll be trying to sell it soon. It's a shame because it's a nice looking truck and handles well. Chuck, the GM engineer said they checked the computer programming on several trucks like mine, and they were all identical to mine. I told the engineer that this website and others have posts from Silverado owners stating they get 20+ miles per gallon. He disputed that and said if my truck did go into v4 under the conditions I've stated, it wouldn't be operating as designed, the catalytic converter would cool down and be out of compliance with EPA emission guidelines. This information came from the engineer in charge of designing the calibration for all the GM light duty trucks. By the way Chuck, this problem does not trip a trouble code. Otherwise, it would be tripping all the time. The computer will stay in V8 if you are going uphill or pulling an extra load or driving into a strong headwind. It's not designed to trip a code because of extra load on the engine. Mine probably has a minor problem somewhere that is creating just enough drag to keep the V4 from working under those conditions and they don't know where to look for it.
The Silverado's new 6 speed transmission isn't the greatest. I bought my Chevrolet for literally thousands less than a Ford, and even bigger difference on the Tundra. I considered a Tundra because I had a 4Runner that was basically flawless for 80,000 miles. The weird frame under the bed of the Tundra scared me away. If you do a google search, you will see numerous transmission complaints with the new Ford F150 as well.
Good luck to you.
Please keep us updated on the progress of your investigation with the dealership; if you want for us to check into it further we can set up a Service Request and do so. Please email us at socialmedia@gm.com with more details (including your name and Edmunds username, phone and address, the last 8 digits of your VIN and current mileage, and the name of your dealership).
Sarah, GM Customer Service
GM considers a quart every 1,000 miles as normal. If the truck had 2,000 or so miles on it since your last oil change it would be considered "normal".
You need to check the oil every other fuel stop. And coach your wife not to stop at an Autozone where apparently they don't know how to add a proper amount of oil.
Luckily, he owned a Device that read codes he got from Napa. It showed the number 6 cylinder was bad and an O2 sensor.
He put in all new plugs, new plug wires and one O2 sensor. He took it for a test drive and within two miles it was it was doing the same thing. The Stablizer and traction control light came on and also the check engine light as it had for me when it started running very very rough. In my case, it was the number 6 plug. Three different GM mechanics at three different dealerships told me that it mostly affects the plugs on the right bank, and can affect any of those plugs, one told me that he had seen it on the number 7 plug twice.
GM is well aware, as well as their service depts since GM has issued bulletins to the dealers regarding this issue. These bulletins are not for the public.
What happens is the fuel mgt system shuts off the fuel to the right bank and the lifters won't lift the valves for lubrication. Then, the lifter fails, the roller for example breaks off, the lifter slides inside itself, etc. as a consequence it wears the lobe off the camshaft, then destroys the camshaft. Replacing the bad lifter and camshaft will not solve the problem, maybe temporially, but not for the long term.
In my case, my pickup went out of warranty, GM refused to fix the problem. If you are having any issue with oil consumption, bad fuel mileage, running rough; RUN DON'T WALK TO YOUR NEAREST GM DEALER ESPECIALLY IF YOU ARE UNDER THE 100,000 MILES AND DEMAND A NEW ENGINE.
Repairing the engine does not work. I was told by one mechanic he saw an engine repaired with a new lifter, etc. and a few thousand miles later, he had the same problem and ended up buying a new engine.
The only thing to do is get a new engine. Guess what? GM now has their fuel mgt. system on the 2013 2500's and as I understand it on the 3500's also.
It looks like I'll be buying a ford sooner than later. We can thank California and the EPA for all this crap the manufacturers have to put on vehicles these days.
However, it really pisses me off with service managers and a district manager lies to me about the problem.
WHATEVER YOU DO, DO NOT LET GM REPAIR THE ENGINE. I BELIEVE, IT WILL COME BACK TO HAUNT YOU.
S0-he did work that really wasn't going to cure the problem and misdiagnosed what the issue(s) were?
How many miles exactly did you have on the truck?
Your truck is out of warranty.
How long do you think any manufacturer should be responsible for your vehicle?
The problem definitely was occuring prior to 100,000.
Apparently, you are a GM employee, your tone certainly indicates it.
How long should manufacturers be liable for mechanical issues? 100K? 200K? 300K?
It's easy to get on the Internet to complain. Harder to get some real facts on this forum sometimes as to what the real circumstances are.
====================================================
Hey rem308
It's obvious that Chuck1 is being paid well by GM. It looks like he's been posting on this site for years and always very quickly degrades anyone's compaint and sides with GM. NOBODY would waste that much time making himself available to respond in the defence of any giant corporation without being paid unless.........., well I can't think of any other reason??
I DON'T SIGN ON TO EDMUNDS JUST TO COMPLAIN.
The thing that gets me agitated is when someone comes on here and says my truck isn't working right because the alternator is discharging. IT'S SUPPOSED TO WORK THIS WAY!
This isn't fair to people who are looking at these vehicles.
Then they try to justify what they are saying because they work on computers.
OK-I guess some know more than the engineers who designed the Silverados.
I agree with you 100% How do we get the word out about these AFM engines? I share your pain too. I didn't realize these were defectively engineered engines until now.
I have a 2008 4x4 Z71 with 5.3L AFM. Primarily highway driven miles with weekend hunting trips, but no heavy duty offroading. Oil changes at recommeded intervals; minimal oil loss between.
At 145,000 miles, the lifters & camshaft went out. I think AFM shortens engine life. I've owned GM trucks(and Fords and Dodges) for three decades & normally get 300K miles from a motor. Of course, GM won't even share in the cost of repair - which is several thousand dollars - as the mileage is out of warranty. Even though I like the styling, handling & performance in muddy conditions, I'll be swapping for a Ford or Dodge or try a Toyota asap.
Like you, if you own one of these engines, be sure to trade if off before the warranty expires, or even better, buy something else to begin with!
How long do you think a manufacturer should be responsible?
100K-200K-300K?
You have a valid question. My answer is "it depends". I purchased my first chevy truck from this dealer in 1985 and several more since then. Have not had internal engine trouble in the past. Have rigorously followed maintenance schedule for safety reasons and to avoid costly repairs such as this. Have paid premium cost at the dealer for such service and expected more from them. Our government also used some of my tax dollars to bail out General Motors during the fiscal crisis. I personally purchased the 2008 Silverado, also helping out GM in their time of need. I could have bought a Dodge, Ford or Toyota. I've had excellent experiences with all three brands.
AFM technology was first used in the 2007 truck. I wasn't aware of premature lifter failure until my truck broke. This was a surprise and not a good one. There is a design flaw in this system. Lifters need lubrication to perform properly over the long term. There should at least be a disclaimer that lifters and camshaft will need replacement after the initial warranty so that as consumers, we can include these costs in our buying decisions. After all, purchasing and maintaining a vehicle for most people is our largest investment after our home.
I wanted GM to at least cover the cost of the parts and for the dealer to discount the labor. Denied by both.
I hope these forums inform others in their purchasing decisions, both for used vehicles equipped with AFM engines and for buyers of new vehicles that intend on keeping them past warranty.
Now, back to your original question. Warranty of 100,000 miles is excellent. Most folks don't drive the high highway miles that I do so probably will never reach that level. For individuals like me that drive a lot, allow the dealer to perform all service work and properly maintain their vehicle, mileage should be extended on engines possibly for lifetime of ownership. They should at least cover longer timeframe for new, untested technology.
If you were planning on working with a GM dealership to get this checked into, we're available to check in on this with them. Please contact us via email at socialmedia@gm.com with more information (including your name and contact information, a brief summary of the situation, the last 8 of your VIN and mileage, and the name of your dealership).
Sarah, GM Customer Service
I knew I had real trouble when I put 87 octane in it. The truck started to spark knock pretty bad at light throttle. Assuming I might have gotten bad gas (bought it at Shell), I put some Heet in the tank. This did nothing. I ran that tank of gas and put two bottles of Techron in at next fill up, and I filled up with 89 octane (Pilot). Slight improvement. The next tank was 87 Pilot octane with 2 bottles of Techron. The truck will spark knock like mad at light throttle at about 45 mph. It seems to me that it's spark knocking the entire time it's in V4 mode. Salesman at Serra told me to "put some Techron in it". I told him I already did and that it didn't help, but no check engine light had come on and would I be wasting my time taking it in for service. He said he'd ask and call me back. I never heard from him again. I took it to a local dealer and complained and left it with them. The tech that drove it heard nothing, and the service manager said that some AFM noise was normal. I tried to believe him because I like the truck, but the spark knock is annoying and is most likely damaging the engine. So, I return to the dealership and drive it with the same tech inside. I keep him in there until it spark knocks like hell and ask if he hears that. He says he didn't hear anything other than exhaust noise. Whatever, everyone else that rides with me in the truck can hear it, and no exhaust noise sounds like spark knock. If it was exhaust noise, it would be more rythmic than it is. Finally, to prove it was spark knock, I filled up with 93 octane. Spark knock almost completely gone. If it was exhaust noise, it would remain the same. I went to the dealership and asked about trading it in on a new 2012 model, and they had one left. I test drove it, and it sounded nearly as bad as mine. I'm certain it is spark knock, and I'm certain the reason it is happening is because the timing is a little off due to weak opening / closing AFM valves during V4. The dealership was nice enough, and sort of eventually admitted to hearing something, but said half of the vehicles with AFM do it and it wasn't worth tearing down the engine and replacing valves, because GM wouldn't pay for it anyway if the offending valves and lifters weren't too far out of spec.
So after a little research and thought, I'm convinced it is indeed spark knock, being cause by bad valves or lifters (which there is a TSB about). I'm also convinced the dealerships have to say they don't hear it or it isn't a problem because GM isn't going to reimburse them for any work unless it's really bad. GM, in order to save money, doesn't believe in repairing something to prevent catastrophic disaster, only repairing the disaster after it happens. So I've got $24k or so in a "certified" (yeah, right) used vehicle that I hate to drive now. I suppose I can put some more 93 octane in it and run it for a while. That'll eat up whatever cost savings I might've gotten with AFM. I considered having the AFM shut off. But, what I'm most inclined to do is fill it with 93 octane and trade it in on a Ford. I know all vehicles have their problems, but I had a 98 Dodge that I loved and always heard the rumors of weak transmissions. I babied that truck and changed trans fluid every 50k miles, only to have it fail twice at 130k and 170k. I sold it with 190k because it still didn't shift gears right. I don't want to try and put Mobil 1 every 3k miles in this truck and run 93 octane to try to avoid the innevitable AFM valve failure. I guess if there's enough rumors of problems with a particular vehicle, they're probably true to some extent. And the AFM rumors are pretty rampant. I know all AFM engines aren't bad, but why would I want to gamble on another?
Sorry for the rant. Not 100 percent sure what my best course of action is to be honest. To sum up, 53k miles now, and I've had it for a month. 10k miles or 11 months on the warranty. It spark knocks like hell on 87 octane, especially in V4 (shouldn't do that if it'll supposedly run on E85), and GM dealer says they can't hear anything abnormal. No CEL....yet. Any advice appreciated. Or I will sell it to you at a great discount if you live in the area.
One thing we can do is document that you're having this concern and follow up with your dealership on this for you. Please email us at socialmedia@gm.com with more information (including your name and contact information, the last 8 digits of your VIN and mileage, the name of your dealership, and a brief summary of the situation).
Regards,
Sarah
GM Customer Service