2014 Sierra 5.3L HORRIBLE MPG...HELP!

TJay74 · February 22, 2016

Winter blend fuel and colder temps will kill the MPG, even without remote start and idle time. Just the cold temps alone will kill the MPG. I have noticed a 2mpg swing going from weeks where the temps were in the 20-40's to weeks where the temps were 50-70's.

Showtime417 · February 22, 2016

Previous owner could have been Running E85 which will dramatically lower MPG. Also it has 24k miles of what ever the previous owners habbits were. I average 20MPG almost always. And we have rolling hills in every directions.

HondaHawkGT · February 22, 2016

Tire size that isn't addressed in the computer will affect the calculated mpg. Idle time HAMMERS the mpg. Short trips HAMMERS the mpg. 87 vs 89+ octane has an effect on mpg. A cold transmission and engine HAMMERS mpg. Bigger, heavier tires has an affect on mpg. Driving style had an effect on mpg. It all adds up.

If i only short trip my truck for a week, my average over 25 or 50 miles is 10-15 mpg during the winter. Once i get up to twmp, my truck is averaging between 20 and 22 mpg on the highway on the winter.

Smoothbassman · February 22, 2016

Winter fuel blend as well as cold temps drop my MPG down to 15-17. It's like clockwork. I have a 26 mile commute that I usually get 19-22 in the summer. Down to 16 now.

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freshstart12 · February 22, 2016

Welp on my 20 mile commute to work I pulled in about 17mpg. That was probably 30/70 highway/city.

I hope it continues to stay up around there. With such a small sample size it's hard to tell.

tnchevy · February 22, 2016

If you are so concerned about MPG's why are you planning on putting a leveling kit on it? That will knock off 1 mpg or so and most who put on a leveling kit will put on bigger and heavier LT tires so there goes another 1 to 2 mpg. After 18 months and 10k miles my truck has averaged 19 mpg calculated by hand, truck says 19.8. I have been getting low 17's in the winter an upper 20's in the summer. Took the air dam off in Nov. so I will know how that effects me after 1 year. The mpgs on these trucks are good but for terrain I drive in the mpg's on my 2014 are about the same as they were on my 2002 (It averaged 18 mpg and had bigger and heavier tires on it).

zmnypit · February 22, 2016

Speedo been re-calibrated? My 14 was getting 14.2 with 285/65/20's with the speedo being about 5mph off. I bought the hypertech and calibrated it, now it stays between 16.5-17mpg.

Bowtie619 · February 22, 2016

Speedo been re-calibrated? My 14 was getting 14.2 with 285/65/20's with the speedo being about 5mph off. I bought the hypertech and calibrated it, now it stays between 16.5-17mpg.

Just came across this thread and new owner of 2014 SIlverado LTZ with stock P275/55R20 all-season, blackwall. I'm halfway through my first tank and only getting about 10-11 MPG. Full tank I was estimated to get UNDER 300 miles for the tank. That was pretty surprising to me as I was expecting upwards of 15-20. I live in San Diego so lot's of highway driving. I know it's too early to tell since I haven't even gone through a tank but I was curious about your comment. I looked up the hypertech really quick, is this a similar product tot he diablosport intune? I'm new to the tuning and calibrating though. I will definitely do some more reading on them...

zmnypit · February 22, 2016

Just came across this thread and new owner of 2014 SIlverado LTZ with stock P275/55R20 all-season, blackwall. I'm halfway through my first tank and only getting about 10-11 MPG. Full tank I was estimated to get UNDER 300 miles for the tank. That was pretty surprising to me as I was expecting upwards of 15-20. I live in San Diego so lot's of highway driving. I know it's too early to tell since I haven't even gone through a tank but I was curious about your comment. I looked up the hypertech really quick, is this a similar product tot he diablosport intune? I'm new to the tuning and calibrating though. I will definitely do some more reading on them...

Its a speedo only calibration. Hypertech 732501 is the part #. Is your speedo off? You can check it with speedview in the app store.

ewbldavis · February 22, 2016

Alot of it is winter. I'm averaging 13-15 now with a light foot.

I was pushing 18 thru the summer. I expect to break 19 this summer since she'll be good and broke in.

freshstart12 · February 22, 2016

Alright guys. Well here's an update.

I drove it today for work. Put about 70 miles on it. 50/50 city/highway. Based on that I'm averaging 17.5mpg. MUCH better.

It was skyrocketing on the highway.

I'll put the leveling kit and removing the air dam on for looks even though I'm aware it'll knock off 1-2 mpg or so. That's nothing a tonneau and cold air intake and summer gas can't remedy right

jamesonjc · February 22, 2016

I am averaging 12.1 mpg on winter fuel in NY. I have a little over 1,800 miles. Eighteen hundred. I am not disappointed because I am full throttle almost everywhere I drive.

About 600 miles of that is four wheel drive hi - another couple hundred in auto.

If I am in 2wd I am doing between 14 an 15 by my calculations.

JC

Bowtie619 · February 23, 2016

Its a speedo only calibration. Hypertech 732501 is the part #. Is your speedo off? You can check it with speedview in the app store.

Thanks for the tip, i just downloaded the app and I'll test it out tomorrow. I'm now at about 100 miles on this tank and still sitting at 10 mpg. Just doesn't seem right...

CH15GMC · February 23, 2016

I'll put the leveling kit and removing the air dam on for looks even though I'm aware it'll knock off 1-2 mpg or so. That's nothing a tonneau and cold air intake and summer gas can't remedy right

Does a tonneau cover really help mpg's? I have a low profile truck box in currently and thought about a tonneau cover but like the box. It it really helps mpg I might lean towards a cover more.