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

77 messages,  Last post on Nov 01, 2012 at 5:57 PM

You are in the Chevrolet Silverado & GMC Sierra Forum.

What is this discussion about? Chevrolet Silverado 1500, GMC Sierra 1500, Chevrolet Silverado 2500, Fuel Efficiency (MPG), Truck

Messages Page 1 of 8

#1 of 77 2011 Silverado, POOR mileage, surging, no check engine light by spaztikhi

Sep 14, 2011 (4:33 am)

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

#2 of 77 poor milage,2011 silverado by gmbailout

Oct 10, 2011 (3:04 pm)

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.

#3 of 77 Re: 2011 Silverado, POOR mileage, surging, no check engine light [spaztikhi] by hotrodjim

Nov 04, 2011 (5:10 pm)

Replying to: spaztikhi (Sep 14, 2011 4:33 am)
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!!!!!!!!!!!!!!!!!

#4 of 77 2011 Silverado 5.3 Active Fuel Management notice by string2

Nov 04, 2011 (8:25 pm)

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.

#5 of 77 Re: 2011 Silverado 5.3 Active Fuel Management notice [string2] by ceb66

Nov 05, 2011 (10:20 am)

Replying to: string2 (Nov 04, 2011 8:25 pm)
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.

#6 of 77 GM- PLEASE CONSIDER THIS! 2011 Silverado 5.3 Active Fuel Management by string2

Nov 05, 2011 (3:13 pm)

Replying to: ceb66 (Nov 05, 2011 10:20 am)
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.

#7 of 77 Re: 2011 Silverado 5.3 Active Fuel Management notice [ceb66] by string2

Nov 05, 2011 (4:06 pm)

Replying to: ceb66 (Nov 05, 2011 10:20 am)
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

#8 of 77 Re: poor milage,2011 silverado [gmbailout] by spaztikhi

Nov 05, 2011 (7:16 pm)

Replying to: gmbailout (Oct 10, 2011 3:04 pm)
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

#9 of 77 Re: 2011 Silverado, POOR mileage, surging, no check engine light [hotrodjim] by gmcustsvcsarah

Nov 07, 2011 (9:49 am)

Replying to: hotrodjim (Nov 04, 2011 5:10 pm)
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

#10 of 77 Re: 2011 Silverado, POOR mileage, surging, no check engine light [gmcustsvcsarah] by spaztikhi

Nov 07, 2011 (7:16 pm)

Replying to: gmcustsvcsarah (Nov 07, 2011 9:49 am)
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.

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