2011 Silverado, POOR mileage, surging, no check engine light

spaztikhispaztikhi Member Posts: 7
2001 silverado ext cab 4x2 4.8L 1400 miles purchased new 45 days ago.



Round trip, Ocala florida to Orlando area. tripometer- 235 miles used a full tank (26 gallons +)

I had the truck to the dealer twice so far in reguards to mileage and the way it runs ** crusing, accelerate slightly, slight enough that it does not down shift and is bucks, like a miss under load, also noticed this condition when in a parking lot, slow holding steady low speed, it feels like your applying light pressure to brakes and letting off (repeating). And other possible related condition, slowing to a stop, close to stopping the truck surges like accelerator is tapped. Sometimes applying slight brake others just letting off to coast toward light. This has happened 4 to 5 times since bought. **AND YES I AM SURE I WASN'T TOUCHING THE GAS PEDAL**



No check engine light, dealer states it was scanned with no codes present. I noticed these things in the first week of ownership. The service advisor told me there was probbably some water in the fuel, and that I need to find a new place to fuel up ***this was the complementary tank of fuel at purchase*** and I have fueled at 8 different places since and no changes.

I had been purchasing F-150's since the 80's. Fords do not get exactly what the MPG estimates state, but I still get 19 highway, and 14 city with my wifes 04 supercrew (4.6L) with a drive by wire configuration like my Silverado.

I love the way my Silverado looks better that the new Fords, but I'm wondering if I should have stayed with what I know.


I feel as if I have purchased a sick, hungry St. Bernard
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Comments

  • gmbailoutgmbailout Member Posts: 3
    yhea,my window sticker said 15/21,more like 12/16 on my pile of regret, add the clankin and banging of gm 6 speed and wa-la- you have been punked, but dont worry, you have a 100K driveline warranty that will make it until it starts to fall apart.
  • hotrodjimhotrodjim Member Posts: 3
    I have the same problems!!! On sept 2 of this year I was involved in an accident because the surged after I applied the brakes and I hit the back end of the car. These trucks are not safe at all!!!!!!!!!!!!!!!!!
  • string2string2 Member Posts: 71
    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.
  • ceb66ceb66 Member Posts: 70
    String2,

    You are correct about the sales people. I was talked into the 5.3 liter 6 speed. I was told the 5.3 gets better mileage than 4.8 liter due to the AFM.

    I would have never considered the 5.3 had I known how uncomfortable the ride was. To add insult to injury, friends with 4.8s get the same or better mileage than I do.

    I read what the engineer told you regarding the AFM at 70mph. Did he comment on the surging? My truck "surges", lags, growls and sometimes bangs when moving from 4 to 8 cylinders.
  • string2string2 Member Posts: 71
    edited November 2011
    ceb66 - within a month after I bought my 2011 5.3 AFM Silverado, I took it to the dealer to see why I was getting such bad gas mileage. I told him that the salesman had convinced me that some buyers had reported to him that they were getting 23 mpg on the highway because of the AFM. He just laughed and said he didn't know why the sales people keep telling everyone that. He also said he had a 4.8 without AFM and was getting about 17 hwy/city combined, which is better than my 15 MPG that I paid extra for. It's plain to see that the problem is the AFM, you can look at the DIC guage see when its not working. I don't see why GM won't modify their computer program and adjust it to stay in V4 at 70+ MPH highway speed (which is normal for most highway driving). They are costing people a lot of extra money to drive their 5.3 trucks. Why not offer to have a small deductible if repairs become necessary as a result of the modification, if this modification is requested by the owner of the truck. Please Consider this GM! Thats better than paying an average of $65.00 more per month to drive this truck.
  • string2string2 Member Posts: 71
    ceb66 - I just noticed your question at the bottom of your post to me.
    I was not given the privilege of talking to the engineer. Just a report from the dealer service manager. I have seen other posts on here about your same problem, though.
    Good Luck
  • spaztikhispaztikhi Member Posts: 7
    I now have 2600 miles, my last test of the mileage was 18.2 hwy. Its getting better, I knew it would get a little better, I have never started out with such bad mileage. I still have the surges and the sputtering, still no check engine light but I do now have a slight tick comming from the left bank. I'm not sure if it is a lifter, injector or exhaust leak, but it sounds like its again time to get to the dealer. I have lowered my truck 2" front, 4.5" rear, I have short legs lol, I can't wait until I get the "your problems are due to your mods" Ever heard of Magnuson Moss?........................

    Does sound like I should be glad I got the 4.8 vs 5.3
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    Hotrodjim,

    I’m sorry to hear about the accident you were involved in, but glad that you’re okay. Can we please learn more? Email us your name/username, contact information, and the last 8 digits of your VIN.

    Thanks in advance,
    Sarah
    GM Customer Service
  • spaztikhispaztikhi Member Posts: 7
    Sarah, Mine is also surging (see the original post on this thread) I was told by my service advisor that its probably due to me hitting accelerator instead of the brake, I assure you it's not. Of course the other concerns were unfounded until I pointed them out to an advisor who would listen, and was then corrected. I have shot across the median cut thru and was unable to stop before my nose was half way in the lane, thank god I was more fortunate than Jim and was able to avoid an accident.

    Any help for one and all sharing this concern would be appreciated.
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    Spatzikhi,

    I apologize for not responding to your post directly – we are more than happy to follow up with your dealership with this surging concern that you’ve experienced with your Silverado. I am glad that you remain safe after the scenario you described in your most recent post!

    Please email us with your name/username, contact info, last 8 digits of your VIN, and involved dealership.

    Best,
    Sarah
    GM Customer Service
  • spaztikhispaztikhi Member Posts: 7
    Thank You Sarah..................
  • jasperthecat37jasperthecat37 Member Posts: 1
    I had the same problem today with my 2010 silverrado. So I put it in park and turned the car off. Restarted the car and it went into engine in low mode so it is at the dealer ship in london, ontario right now.
  • fp2tallfp2tall Member Posts: 2
    I also have complained about the poor fuel mileage to the dealer along with the associated trans problem. I was told that is the way it works with the clutches in the trans, as for the fuel mileage and the dragging feeling, I went from Ft. Pierce to Orlando and returned, 256 miles and used 17.9 gallons of fuel for an average of 14.3. This was at 72 MPH and cruise control most of the way. Far cry from 15/21. It had been averaging 13.9 without cruise control.

    I also found that the caliper on the left font was 60 degrees hotter than the right front after only 3 miles of driving. reported to the dealer and they checked and verified this was so, after tech services call stated that until it is 300 degrees or more, not a concern.

    I also being a multi time GMC truck buyer am very displeased with this model and regret the purchase.
  • string2string2 Member Posts: 71
    edited November 2011
    I thought my gas mileage was bad, yours is worse than mine! The bad thing is, if those dealers can't find a trouble code, you're dead in the water. It's their excuse not to have to deal with the problem. Either they don't have the time to troubleshoot or they don't know where to start to find the problem without a trouble code. In this computer age, I think the mechanics are only taught to respond to a computer pointing at what they need to fix. Otherwise, they think nothing is wrong. GM reads the posts on this site. They may try to help, but all they will do is call the service manager where you had your vehicle looked at and respond back to you with the same thing they have already told you. By the way, did you try driving 10 or 15 miles to get the wheel temp. higher. Do you think the rotor could be warped and barely touching as it turns? Make sure emergency brake cable is adjusted right. Air filter, fuel filter and run injector cleaner thru.? I've heard cleaning the throttle body and the backside of the throttle butterfly can sometimes help. Also, cleaning inside of air tube leading to Throttle body (real good to make it smooth) can help. This may not help, I just thought I would bring it up for your consideration. Some on this site say that we complain too much and we should have known that these trucks won't get the kind of mileage they advertise. But as you read their posts, you see that their mileage is pretty good. What's up with that?
  • ceb66ceb66 Member Posts: 70
    edited November 2011
    My mileage hasn't beat my friends' with the "older" 4.8. The same 4.8 the GMC salesman said gets less mpgs than the 5.3 .

    Those lucky guys have the old-fashioned, proven 4 speed, that doesn't clunk bang slip growl and lag like the clumsy new 5.3 liter six speed with active fuel management AFM !

    In fact, this brand new truck with all kinds of computer controls, that according to General Motors, I should be marveled by, GETS VERY SIMILAR MILEAGE TO THE 2004 F-150 WITH 115,000 MILES ON IT THAT I SOLD SO I COULD BUY THIS RATTLE TRAP.
  • hotrodjimhotrodjim Member Posts: 3
    Update!!!
    since my first post back in sept things have all gone downhiill. my truck spent 7 weeks in the shop getting fixed. when i got it back i continued to have the transmission problems and the brake system has failed me 3 times!!! thank god no accidents. and after a week and a half gm says the truck is fine. PLEASE PLEASE PLEASE if you are thinking about buying a gm truck DONT!!! These trucks are not safe and gm does not stand behind them at all.I have no other option but to get a lawyer and fight.
  • hotrodjimhotrodjim Member Posts: 3
    Purchased a new truck on 7/5/11, within the first 7 days of owning the truck the "Service Brakes Soon" light comes on.....pull to the side of the road, call On Star (truck too new, acct. not activated yet). Turn the truck back on....the light goes off, we think "good to go". Fast forward to 9/2/11 - vehicles turns infront of me, I am travelling a safe distance behind, doing the speed limit (I drive truck for a living so I know how to handle a large vehicle and allow ample time for braking). I SHOULD have been able to SLOW/STOP the vehicle....THINK AGAIN! I flipped the vehicle infront of me TOTALLING it and $10K of damage on my truck sending 3 people to the hospital. 7 Wks later I get my repaired sierra....ONLY TO HAVE the "SERVICE BRAKE SOON" light APPEAR. Fix attempt #1 - "O" ring repaired. Brakes squealing...service says "no longer using aspestis in the brakes, ALL brakes squeal" (don't know about you but I don't hear this on every new vehicle on the road). According to GM service the truck is "operating as designed" (great...operating with faulty brakes there is a stellar design concept). Get the truck back...driving on the highway..."service brakes soon" light #3, in for service again....this time the "replaced the sensor" (Attempt #2). Pick the truck back up on Tues. of Thanksgiving, we go away for the holiday (NOT DRIVING THIS NEW TRUCK...take my wife's RELIABLE Honda). Get back on Friday after Turkey day....squealing in the breaks...drive to the dealer. Service guys comes out the listen (as they suggest to bring it in when it is making the noise). Yep, Jeremy in service hears it. Next thing you know....."Service Brakes Soon" light #4....in to the dealer we go....OH this time we have significant amts. of air in the brake lines....booster replaced. Fast forward through the HORRID customer service experiences with GM (not the dealer). All kinds of claim files opened because of the accident, we tell them we want a new truck....even willing to settle for a replacement (reconsidered that now I have done more research). GM Claim tells us today....Accident is NOT due to faulty product! Zone Manager reviews and says "truck is fixed now they them to come pick up their truck"!!!!!! ARE YOU SERIOUS GM? Apparently someone has to be SERIOUSLY injured by their FAULTY vehicle for them to pay attention??!! STAY TUNED...BBB arbitration filed, consulting an atty. because we will NOT risk our lives or anyone elses to drive around in this vehicle! BUYER BEWARE if you are considering GM, they do NOT STAND BEHIND their product or care about the future sales that they are "driving" away! MAN do I MISS MY FORD!
  • spaztikhispaztikhi Member Posts: 7
    edited December 2011
    I was wondering if you had heard anything from GM since you were asked to send the Customer service rep your info (vin ect.) I was instructed to do the same, NO REPLIES for me. How many weeks ago was this? I am cringing, I was raised in a bowtie family, I have 1 8 4 3 6 5 7 2 burnt into my brain (smallblock fireing order) never to be removed. I have only bought Ford trucks before because of all of the Ford dealers I have worked for, otherwise they too would have been bowtie. I feel sickened by the thought of being trapped in this truck for a long time. I cannot just trade the truck off and go back to the F-150 thanks to the economy.

    I have had WAY less than desireable experiences with my Chevy deealers service Dept. since buying this truck. I feel like this may be the normal, and wow I bought an extended warranty. I sure hope I don't need to used it. I would much rather waste my money that way, than need it and be facing this kind of service.

    Thank God I have not had any more surges, but it is still sputtering, and once again the pulsation in the brakes is comming back (3200 miles) and I am noticing a lower speed wobble (tire or rim problem) I'm wondering what will be the response I get this time?

    Remeber what I said about the love of the bowtie? Think if I can do this, (check you links below)"> I might know what I'm talking about when I say "THERES SOMETHING WRONG WITH MY NEW TRUCK!"

    ">https://www.facebook.com/#!/photo.php?fbid=1031619467511&set=a.1031618627490.550- - 2.1136120156&type=3&theater
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  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    I am so very sorry for the delay, spaztikhi. There may have been a few glitches in communication on our end, as I am not the only Customer Service Representative responding to the emails that come in from Edmunds. We've solved that problem now, but again I want to apologize that your message was part of the miscommunication. Please, if you're willing, resend your email and we'll be sure to get things moving.

    Thank you for your patience,
    Sarah
    GM Customer Service
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    edited December 2011
    All,

    If you have sent an email to us and have not heard back, there was some miscommunication between myself and another member of our department (as I am not the only person handling the emails coming in from Edmunds). This glitch has been resolved, but some messages may have been lost in that transition. I apologize for the length of the delay, as I do realize that we rely so heavily upon our vehicles for our day to day lives and that vehicle concerns can have huge ramifications.

    I would like to invite you to please re-send your email if you have not heard back from us, and extend my sincere and humble apologies for the delay.

    Sarah
    GM Customer Service
  • string2string2 Member Posts: 71
    I too have had noting but trouble with the service from GM dealers, a gm engineer and all the way up to gm's main office.
    If the dealer can't find a trouble code, then you just think there is a problem when there really is not a problem, in their opinion. The trouble code gives them a justifiable way to keep from spending time troubleshooting the problem. I really don't think they know how to do it otherwise. Good luck with ALL the GM service assistants. They are really just pacifying you and trying to make you feel like they are trying to help with YOUR problem. When all is said and done, all they do is call the dealer where you had your truck looked at, and report back to you that the dealer was right. My problem was with the Active Fuel Management system not working at normal highway speed. It shows on the DIC gauge that it is not working, but they insist that it is working normally. If I don't want to void my warranty, i'm stuck with waiting until it expires before I can have an after market computer program installed to correct the problem. My 2011 Silverado now has 4600 miles. 93,400 miles to go at 16 MPG on level highway..
  • chuck1chuck1 Member Posts: 1,405
    "My 2011 Silverado now has 4600 miles. 93,400 miles to go at 16 MPG on level highway.. "

    How fast are you going?
  • string2string2 Member Posts: 71
    edited December 2011
    "My 2011 Silverado now has 4600 miles. 93,400 miles to go at 16 MPG on level highway.. "

    How fast are you going?

    Between 60 & 70 mph - actually, slower than normal open highway speed. On level ground, not pulling or hauling, plenty air in tires and not windy. Seems like thay wouldn't build them with those restrictions? Well, its only money.... lots of it!
  • chuck1chuck1 Member Posts: 1,405
    Your AFM should be coming on at least part of the time under those conditions. It will not come on much once you hit 75.
  • string2string2 Member Posts: 71
    edited December 2011
    Your AFM should be coming on at least part of the time under those conditions. It will not come on much once you hit 75.

    I think so too! But GM tells me it is working normal, dispite what other drivers and the specs say.

    It will work for short distances at around 62-63 MPH, but under those same ideal conditions and I don't have the air conditioner on. With the air on, it quits working around 58 - 60 MPH. I'm hoping it will get better, but it seems like it should be broke in by now with 4,600 miles.
  • spaztikhispaztikhi Member Posts: 7
    My issues started with my first visit to the service dept with about 5 minor concerns (mileage, sputtering and brakes included) One of the concerns was a cut in the dash (trim over the top of insturments) and I asked the service writer to, 1- replace it if is a seperate part, or 2 DO NOT replace if it is only serviced with dash assy. I told it was part of dash. Another concern was the radio. The aux port on the front of the radio was loose (plugged ipod in and got terrible static and feedback when touching brakes) among a few other things.

    I sat in the service drive with the writer and demonstrated all items on my list at the time of drop off, made a detailed list and gave it to the writer (just to help) I was told a week earlier that a loaner would be waiting for me at drop off. Well nope I couldn't get one unless they were sure it would be there over night. Ok could have told me this a week earlier and I would be fine with it. I asked to please notify me asap if they had to keep the truck so I could get a way to the dealer after work (5pm quitting time) no calls no nothing, I called and was told "oh yeah ummmm we will not be done today (5:05 pm) come and get your loaner" Hmmmm how am I to get there?

    When I went in to pick up the next day, I asked if I got a copy of the work order (what they found, what was done ect.) No it will be mailed to me. I got in my truck to leave, Now my radio does not play out of lt speakers, went back and asked whats up with that? I was told that there was no prob found with radio.

    The brakes still pulsated, radio didnt work, dash wasn't repaired, Oh yeah Did I mention that I an ASE certified and I-CAR certified? I have been not only a heavy collision repair tech. but I am also an A/C, Suspension & brake, Electrical specialist. I now am a service writter / estimator at a large Independant body shop, Oh by the waythe dash part WAS a seperate part, I pointed this out to the writer and he ordered the part, I called to check on the part (is it in yet?) after 2 weeks I was told the part was not in yet 8/11/11, I called parts dept for work related orders and I was asked if I was ever going to have part installed because if not they would have to send it back (only able to keep warranty part for so long)

    Theres FAR more than these issues, I could go on and on. But this final note..... After 4 weeks of this I HAND DELIVERED my reply to the "Are you satisfied with our service letter" explaining why My answer would be no, Which includes all the above and the derogitory comments the writer had made when he didn't know I was behind him, to the Service director (9 pages) I still have not gotten so much as a BITE ME from anyone. Why? the Directors son, Is the service writer. I'm getting mad all over again!

    Yes Sarah I will resend my info to you when I return to work on 12/19. but as you will see in the letter I sent (the reply to your first reply) I am not so sure I want to deal with the same dealership.

    Thank You
    Dennis L Steinhart
  • shack4tomshack4tom Member Posts: 10
    Hi, I was considering a Silverado for my next purchase, what size motor and do you think the crew cab cuts the miles per gallon a lot?
  • chuck1919chuck1919 Member Posts: 176
    I have the 5.3-2011 crew cab and get between 13 and 14 stop and go city. I have also achieved between 18 and 20 mpg highway depending on speed. It gets best mpg at no greater than 70mph.

    Remember these things weigh 5,000 pounds and are shaped like a refrigerator, not the best for mpg.
  • string2string2 Member Posts: 71
    I'd be satisfied with that! That sure is a lot better than 16 MPG at 70 MPH.
  • chuck1919chuck1919 Member Posts: 176
    String,
    We are all aware that your truck is an exception and having issues. Thank you for once again reminding us of the terrible mpg you are getting with your truck. Your truck is an exception of not hitting the "high teens" on the highway.

    Shack - these trucks are great values right now and there are deals to be had.
    Good luck!
  • string2string2 Member Posts: 71
    String,
    We are all aware that your truck is an exception and having issues. Thank you for once again reminding us of the terrible mpg you are getting with your truck. Your truck is an exception of not hitting the "high teens" on the highway.
    Chuck
    ====================================================
    I'm glad to see that you and the other regulars here have been throughly saturated with my complaints about my poor gas mileage and "Active Fuel Management" problems that can't be corrected. I guess most people do feel like, problems are not really problems, as long as they are not their problems.

    But i'm really wanting to let the new readers know how GM takes care of their customers when there is a problem they can't identify.
    According to GM, my gas & AFM troubles are not issues. They say it's operating normal if there is no trouble code (no matter what). You bought it! get use to it! sell it, if you can...leave us alone!
    String
  • shack4tomshack4tom Member Posts: 10
    But i'm really wanting to let the new readers know how GM takes care of their customers when there is a problem they can't identify.-quote.

    Ok, it is a help to be reminded. My cousin and his brother both big wheels in GM but gave me no help with my 04 Saturn issue neither can they help me find a job. They have no time for the little people. I still am going to buy American. They don't help me with any discounts either. I know of a certain person with a Yukon Suburban 374,000 miles and still running strong so that says a lot. I am seriously considering the Silverado with the 5.3 or 5.8 and I know that I will never return to the dealer except to trade it in after 20 years. I lke to read of all these issues and put it all together, I don't care for big advertisements but would rather sit in the complaint dept and take notes. Thanks for your venting and give me more.
  • shack4tomshack4tom Member Posts: 10
    In your own opinion what would be in store for me, if to purchase a brand new Silverado 5.3L with reg cab? MPG, odometer reading when I drop off at the junkyard and how many years of service? I change oil (Mobil 1) every 3000 miles, good maint and I don't tow any thing, driving on good roads (not Michigan). Spaztikhi, Chuck1919, and String2, Servicetech and anybody else-all of your comments I value.
  • string2string2 Member Posts: 71
    In your own opinion what would be in store for me, if to purchase a brand new Silverado 5.3L with reg cab? MPG, odometer reading when I drop off at the junkyard and how many years of service? I change oil (Mobil 1) every 3000 miles, good maint and I don't tow any thing, driving on good roads (not Michigan).
    ====================================================
    Shack4tom,
    Sorry, I can't give you any first hand advice on the 5.3 engines, other than what I've read. My opinion (guess) is that you should get 250 - 300,000 miles out of it. If the one you buy has a properly operating " Active Fuel Management " system, you probably wil get good service out of the truck. If you won't be pulling anything with it though, you might want to check on one with the 3.08 rear end. It might get you a little better gas mileage. These trucks pull strong and seem to be built solid. I would be very satisified with mine if the Active Fuel Management system would work properly. Because of that, I only get about 16 MPH on the road, and they tell me it can't be fixed. Others posting on this site say they get close to 20 MPG. Good luck!
    String
  • fp2tallfp2tall Member Posts: 2
    The truck only has 3000 miles on it. I was told that if I wanted to bypass the AFM system to shift into manual mode and select the 5th gear and see the mileage that way. I tried this and found that 5th was too low and the RPM's stayed too high. I tried 6th in manual mode and the mileage was just as bad (13.4 hwy). I guess with the way it shifts so badly, terrible mileage and fluctuating idle, I need to paint it like a lemon and put sunkist stickers all over it. In the back window warn other potential buyers of the problems that GM will not correct.
  • chuck1chuck1 Member Posts: 1,405
    edited January 2012
    Here is another post that yet needs clarification. First off, 3,000 miles is way too early to start measuring mpg. When I got my truck the first 5,000 miles the city mpg was really bad, and then got better.

    The truck DOES NOT REV much higher in 5th than 6th. I keep mine in 5th in city driving. NO reason to have the truck shift to V4 for a very short distance. In addition, the trucks transmission needs to "learn" your driving style.

    The truck does not have the smoothest transmission on the market, but you have a 100,000 mile power train warranty should the transmission go out.

    The Toyota has bed bounce, the Dodge Hemi sucks gas, and there has been a few blown turbos on the Ford Eco boost. Take your pick which one you should have bought.
  • string2string2 Member Posts: 71
    edited January 2012
    Hi fp2tall
    I'm glad to see i'm not the only one with this problem. Maybe if more people with "Active fuel Management" problems would post their problems on this site, GM might actually start believing their really is a problem! Mine has over 5000 miles and it's not any better at all.
    Thanks for your input.
    String
  • smurf57smurf57 Member Posts: 1
    Purchased a new 2011 Silverado 02/03/2012 now have 66xx miles have had to dealer twice this week for poor mileage, (has always been bad but read posts and gave it time to break in). I averaged 14.6 mpg on the truck on a trip from Marble Hill, Mo to Corpus Cristi, TX and return.The service manager has done 2 "fuel Efficiency tests" (@70 mph) first one was 15.2 mpg second one was 15.0 . The truck is throwing no codes so GM says nothing is wrong, GM suggested I take off bug shield, which I did today (which according to GM the bug shield is changing the aerodynamics of the truck causing the bad mileage), I am supposed to take truck back to dealer Monday 04/02/2012. I just wish GM would man up and fix the problem.
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    I'm sorry to read that you are not 100% satisfied with your Silverado at the moment, smurv57. Looking forward to hearing how your visit to the dealership goes today.

    All the best,
    Sarah
    GM Customer Service
  • string2string2 Member Posts: 71
    I've had the same problem as you since day one on my 2011 Crew Cab Silverado 5.3 six speed trans. My advise to you is, try not let one of GM's engineers look at your vehicle. He will only confirm that there are no detectable trouble codes. That info will then be tagged to your VIN number. Once that happens, none of the dealerships will check your truck without getting GM approval. GM will then deny there is a problem and refuse to do anything related to that problem because there is no trouble code. This lets everybody off the hook, except you, holding the bag! Effectively, that voids your warranty as far as anything related to that problem, sneaky huh!. If you look at your Inst. fuel economy (DIC gauge) , most likely you will see that your engine's "Active Fuel Management" is not working at normal highway driving speed (around 70 MPH, when most needed). That is where you can see when the engine changes from v8 to v4 mode (that does not trip a trouble code when not working correctly). I have read that ithis is mostly a problem with the 5.3 Vortec engines with the six speed transmissions. I think if GM wanted to fix the problem, they would recalibrate the vehicle computers for that model truck. Good luck! Just wait till you hear all the ridiculous excuses they give you.
  • chuck1chuck1 Member Posts: 1,405
    HALF TRUTH ALERT!

    String the AFM isn't working IN YOUR TRUCK. It's working in the other half million units on the road. My truck included. I can consistently get 20mpg at 70ish with the AFM activated on the highway.
  • string2string2 Member Posts: 71
    Okay Lucky! Go ahead and rub it in! We know yours works like it's suppose to. The only way you could be getting 20 mpg is for your AFM to be working in v4 as it should at hwy speed. But I would like to know how you came up with those conclusive facts that every GM truck, but mine, works like yours and is averaging 20+ MPG.
    There are many, many GM truck owners who have never visited any website. There are at least 14 reported posts on this website that say they are also having problems, not to mention complaints on other websites or those that didn't post their complaints at all. I know how they are supposed to work (like yours). All these trucks should get that kind of gas mileage. However, I think you have to agree, these complaints should represent a considerable number of problem GM trucks on on the road.
    You have helped to make the point for me and the other problem GM truck owners though. As you have just acknowledged, yours is operating normal!

    GM tells me mine is working normal at 16 MPG on flat highway @ 65 70 MPH without the AFM working at all. AND, they won't try to fix it.

    By the way Chuck, does your truck have 6 speed transmission or 4 speed automatic trans.
  • chuck1chuck1 Member Posts: 1,405
    "By the way Chuck, does your truck have 6 speed transmission or 4 speed automatic trans"

    The "clunky" six speed. (Yea, mine clunks too!)
  • daninrapidandaninrapidan Member Posts: 5
    edited October 2012
    Purchased my 2011 Silverado 1500 LTZ Crew Cab October of 2011. The first 7000 miles were at 17.7 miles to the gallon. AFM worked perfectly. About 7500 miles the voltage guage started doing the dip below 14v on the guage, and I noticed the trucks mileage started dropping. Then the misshifts, hesitations, coughing, started. I also noticed how HOT my garage was getting after parking the truck in it, you could hear the tinging of the metal cooling down from the exhaust system. I had mentioned the poor running condition to the dealer and was told it was probably bad fuel. I choked on this for a while, and then the soot on the tail pipe started as the mileage dropped. Complained, to no avail, normal normal. .... Labor Day 2012, I bring the truck in and say no more, something is wrong. No codes, but they noticed that the Alchohol content is reading 0% all the time, and the fuel in the truck is 15% Alchohol. They re-learn the Alchohol content, and the truck is normal until the very next tank, which happens to be Ethanol free fuel. Im back to the poor running condition again.
    Fast forward to 14k miles. Im down to 13.3 MPG, clunking all the time, and its surging like Im being rear ended. This truck does not like to coast at all, resuming any acceleration causes it to hesitate.
    Service department says that they see what my complaint is, but cant fix anything because corporate says its working as designed and wont let them do anything. This "anomale" only happens to be on the 2011 1500 AFM product line. Thing is, they say the delay they put in the accelerator is normal, and its to save all the torque from being dumped on the transmission. Obviously with it the hesitation getting worse, the torque placed on the trans (the clunking), the worse the trans gets.. how is this delay or hesitation helping my transmission again GM ???? 46,000 dollar Mistake is all I keep saying to myself, should have kept the 2006 Ford that got a consistant 15 MPG towing or solo. This is the Last GM product I will ever buy with this kind of lack of integrity from Corporate. Obviously reading here, there are alot of other people that are having the same exact issue with their trucks ...... if anyone is watching, I would love to know what gear ratio the trucks with this issue are equipped with.... Mine has the 3.42's ???????????
  • chuck1chuck1 Member Posts: 1,405
    About 7500 miles the voltage guage started doing the dip below 14v on the guage, and I noticed the trucks mileage started dropping.

    The alternator has a energy saving feature that turns it down when the system is not needed.
  • daninrapidandaninrapidan Member Posts: 5
    edited October 2012
    Not needed ??? when has 9V been the same as 12V ??? If you have ever wrenched before, and changed an alternator, battery or starter, you will see that the manufacturer or re-manufacturer states Voltage must be 12.7 for them to guarantee their parts. Starter manufacturers would prefer you replace the battery at the same time as the starter....

    Of course its normal, Im well aware of the alternator doing this, we have a 2007 and 2008 3500 Duramax, 2010 1500 LTZ, 2011 1500 LTZ ( this one ) and a 2012 1500 LT, so Im well aware of the issues of these trucks, Im saying that my PCM has probably more issues since this voltage drop, and trust me as much as that needle drops, it also pegs max out to the top of the line they drew so that they dont have to explain this "feature" , they can point and say "NORMAL" just like everything else is "normal"
    GM tends to take a great idea and over complicate it. What possible mileage gain can be seen thru turning off an alternator ??? That same gain gets lost when it has to work twice as hard to pump up a weakened battery. Also, my power inverter HATES this voltage drop and will not power up my laptop on trips as the voltage is too low, as it sees that as a battery drain .. Dealer says ... so what, its not our power convertor and wasnt sold as a chevy option......
    As a computer technician, I can tell you how many PC power supplies in both desktop and laptop computers I replaced due to faulty power supplies. Problems disappeared once the computer got "clean" stable power. Computers that are underpowered get unpredictable, and you cant tell me an automotive PCM is not the same as a regular computer, its more of a specific task oriented device... but they are pretty much the same animal running on the same 12V DC platform.
    What amazes me is, Our $46k cars are not our own anymore, the corporation still owns them and will tell you how they are supposed to run and deny any claim if they can pin it on something else....... In this case, the delay they say should be there is .006 sec upon stepping back on the throttle, and Im saying its a full 3.0 seconds, thats a HUGE difference, one that can be felt most of all about 20- 35 MPH ( school zones, traffic conditions, curvy roads ) and YES, the dealer READ verbatim the blurb from GM about the .006 second delay ...... his response was to stop "tromping" on the gas pedal, well you cant tromp on the pedal in bumper to bumper traffic !!!!!!!!!!!

    OH !!!!!!!! yes, I was also told the heavy soot on the tailpipe was caused by a non GM chrome tip on the exhaust, to my reply of - its part of the Z71 chrome package shipped out from the factory with it on.... stopped him dead in his tracks on that, but he said he would check for a "bulletin"
  • chuck1919chuck1919 Member Posts: 176
    You should be driving a 1960s model. That way you could change you plugs condenser and points every 12000 miles. Your frustration is you need to buy 100k worth of computerized equipment to work on your truck.
  • daninrapidandaninrapidan Member Posts: 5
    We have a G30 old church van, 355,000 miles with a 350, and the old TBI system. 1000 lbs of tools in it, and on regular unleaded its getting 15 consistantly.

    The 600$ programmer that will fix the issues, I should not have to spend, as well as violating my warranty. Not for a sticker price on THIS truck of over $46k. To be by the service department and the mechanic that GM has built these hesitations into the sub routine in the computer to "save" the transmission, and the EPA wont allow them to fix it is utter bull ****. Why is my GM vehicle running worse than the first 7500 miles ??

    I would appreciate only useful comments on the issue, what or who fixes the problem permanently. At this point, my brother is right, find a decent older truck, and dump 46k into repairs and upgrades and have a real vehicle.
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    daninrapidan,

    If you're not already working with Customer Assistance and wanted for us to check into this further with you and your dealership, please email us at [email protected] (include your name and contact information, a summary of the situation, the last 8 digits of your VIN and mileage, and the name of your dealership).

    Sarah, GM Customer Service
  • chuck1chuck1 Member Posts: 1,405
    Here is a useful comment for you. Do a search on the internet and find out exactly what the characteristics of these transmissions are. Then, you can make make an informed decision on how to proceed.

    1) You can see if others are having the same issues.
    2) You can see if they have been able to have them fixed.

    It will lessen your frustrations.

    I already know the answers to these questions.
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