2011 Sierra Erratic Fuel Consumption

Hunter_745 · September 15, 2011

Hi There, I have a 2011 sierra nevada. My 5th Chev/gmc product. I have had nothing but problems with this truck. Has been in shop more in 6 months then all my other vehicles combined. The latest issue may be a deal breaker for me though, unless it can be resolved. From 0 to 15000 km I averaged 450-500km per tank of fuel, no matter how I drove, or whether I was hauling. Over the last 3500 km, I can range anywhere from 325-400 on a tank. It will do this for two or three tanks, then one normal 450-500 tank. The truck also runs like crap. The service guy hooked up to the code reader, seen no codes and said I was good. Didnt I know a full size truck was gonna burn Gas? Not helpful....I asked what could be the issue, He said something about brake drag, transmission slip, and some other bull line.

Some of the issues so far-Broken mount pin on rear shock-front bumper replaced due to rust-has gone out of alignment twice {(less then 18000km) apparently im a bad driver}-computer had to be reprogramed due to windows fogging-service engine light comes on-then goes out in a few days-

Can anyone offer me helpful advice. I'd frefer not to trade in a 6 month old truck and take a loss....

randas · September 15, 2011

Sorry can't help you with your issues but you definitively have something wrong. My 07 NBS easily gets 650-700 kms on a tank and when I fill up its 85-90 liters. (Filled today 670 kms, 86L to fill) And thats with a rough idle that I need to get looked at...

I think there is some kind of lemon law if you have that much trouble with a vehicle but someone more knowledgeable will have to chime in

pm26 · September 15, 2011

This is a tough problem. If no engine codes are thrown, GM will simply say that there is no issue and that the bad fuel economy is due to your driving habits. You may have a bad sensor somewhere, such as the MAF sensor that still works within the required parameters so the code does not show, but feeds false info into your ECU, and your air-fuel mixture is possibly off.

My brother has a similar issue with his '98 Nissan Maxima - the car gradually lost its performance and is utterly gutless and no engine codes show - as if it was purposely leaning itself out due to erroneous feedback by some sensors. The local Nissan dealer gave him some BS about the age of the car, which is irrelevant. The engine and the car are in great shape, the transmission is 5 speed manual and prior to this the car was real fast. It is as if it suddenly lost 1/2 of its horsepower. Still runs and idles smooth, just no power.

dataspng · September 15, 2011

If you have an engine light coming on and off somethings wrong... if they are a good dealer they can put a black box on the truck and let you drive it a few days to try and record the errors that are not logged. Been there done that on a problem a few years back on company truck that only tripped and engine light while towing.. worked great and the found the problem (a sensor in the transmission was out of spec, but not bad).

By chance is it a E85 rig and have you ran different tanks of E85 and Regular unlead through it? I seem to remember a TSB on the "proper way" to mix fuel and if it gets out of wack it can really screw up you gas mileage and power.

ruggedlife · September 16, 2011

computer had to be reprogrammed due to windows fogging??? anyways are you filling up at the same station every time? does this station get gas pumped in often? sounds like maybe poor grade gas, try a different station for a while, and dont fill up if you see the tanker there it can stir up any sediment in the tanks underground that you're about to pump into your vehicle... make sure gas cap is all the way tight etc etc. im assuming you already eliminated operator error by making sure you drive consistently? i for one know that i do not drive consistently at all and that can make a massive difference...

Hunter_745 · September 16, 2011

I try to drive as cosistenly as possible, And have been taking averages. The 2005 sierra I traded in would get 650-800 km to a tank, but it was a reg cab with a larger tank. Dont think lemon laws apply where i live, and it doesnt matter where i fill up, all the gas comes from same distributor ( I live on an Island ). If this is going to be an ongoing problem that is hard to fix, then i'll have to get rid of this truck. 150km drop in a tank is 18-25 bucks a tank.

no e85 available here either.