2014 Sierra 5.3L HORRIBLE MPG...HELP!

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.

Ok, I tested on the drive to work, all highway driving for the most part. Turns out the phone app had me at a constant 6mph over my dash displays. So, it looks like this could be the problem. That seems like a large number to be off though. I'm not sure I totally trust the phone app yet but I definitely feel like this could be one of my issues....

freshstart12 · February 23, 2016

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.

Yeah I'm sure it does little to nothing...I was just joking trying to justify a leveling kit loss in MPG haha.

However there are articles like this all over the internet...so its going on!

http://www.realtruck.com/tonneau-covers/tonneau-covers-improve-gas-mileage/

zmnypit · February 23, 2016

Ok, I tested on the drive to work, all highway driving for the most part. Turns out the phone app had me at a constant 6mph over my dash displays. So, it looks like this could be the problem. That seems like a large number to be off though. I'm not sure I totally trust the phone app yet but I definitely feel like this could be one of my issues....

That's what mine showed with 285/65/20's. I bought the hypertech, plugged in the new tire size then rechecked with the app and its spot on.

edit: I just realized you had stock tires. Speedo shouldn't be off then???

Bowtie619 · February 23, 2016

That's what mine showed with 285/65/20's. I bought the hypertech, plugged in the new tire size then rechecked with the app and its spot on.

edit: I just realized you had stock tires. Speedo shouldn't be off then???

So you never had issues until you put on the new tires? I have the stock tires but I just recently bought the truck. Only halfway through my first tank. But I am definitely seeing the speedo off by 6 mph. That with the issue of my mpg hovering around 10-11 doesnt seem right...I think I am going to buy the hypertech tuner...There is a sale going right now and I can get it for 300$. It looks like the tuner does the speedo correction as well.

Bowtie619 · February 23, 2016

That's what mine showed with 285/65/20's. I bought the hypertech, plugged in the new tire size then rechecked with the app and its spot on.

edit: I just realized you had stock tires. Speedo shouldn't be off then???

Is it possible that stock would be considered just the 18 inch rims? Maybe my truck wasn't tuned for the 20 inch premium wheels?

zmnypit · February 23, 2016

Is it possible that stock would be considered just the 18 inch rims? Maybe my truck wasn't tuned for the 20 inch premium wheels?

Its possible I guess. Open the drivers side door and it should show the oem tire size in the door jam.

Bowtie619 · February 23, 2016

Its possible I guess. Open the drivers side door and it should show the oem tire size in the door jam.

Good call, it has the correct rims and tires listed so that doesn't explain why I would be off so much. I'm going to test on another phone. Either way I ordered the Hypertech tuner so hopefully I can get this squared away...

ShotgunZ71 · February 23, 2016

If the tires (not just rims) are stock size, the 17, 18 and 20" tires are all the same diameter, so the speed would be the same for all of them. Once you get up to the special 22" rims, I believe their is a slight difference.

When I had my 2014, I sold the 18" set and bought a 20" set and was good to go with no changes.

beerguy214 · February 23, 2016

just a bit of information but if you thought you would see a lot of gain in mpg you should of bought a Malibu.These trucks are over 5,000 lbs and unless you reduce the weight by a significant amount it is not going to get a lot better.1-2 mpg better by buying a new truck is your call but even a 2017 will see 1-2 or maybe 3 mpg gain.It is a truck so don't expect much improvement

07Softail · February 24, 2016

Hey Guys,

Just bought a 2014 Sierra 5.3L w/ 24,000 Miles on it.

When I went to buy it the MPG said 12.3....I contributed that to the previous owner having a lead foot.

So I reset the meter. I have put about 50 miles on the truck so far....I'm averaging 13.5mpg...Not anywhere close to what I was expecting..

It does have aftermarket tires on it from the dealership but that's it...I mean, I was expecting 17+ MPG!

I'm really concerned about this since I do a lot of driving for work. I'm considering going back to the dealership tomorrow and demanding my 2013 Silverado back..

Any suggestions? I'm freaking out over here..

LMFAO!!!!! Run a full tank and gauge your mileage from that. But Winter gas will kill efficiency.

HondaHawkGT · February 24, 2016

Yup. The if the truck sat idling for 5 minutes, it makes a huge impact on the rolling average.

TJay74 · February 25, 2016

Actually all of the stock tire sizes are the same rolling circumference for the 17, 18, 20, and 22 inch wheel/tires. They all use the same values in the ECM for the tire size.

royalkangaroo · February 26, 2016

I just purchased a 2015 Sierra Z71, 5.3 with 3.42 gears last month. My 2010 averaged about 16.5 all around. Winter/summer, long trips, short trips. It probably varied from 14-20.

My '15 thus far has averaged 11.5mpg around town (30-40mph stop and go). And about 16.3mpg in the last 500. I agree with the previous posts, I use the remote starter a lot up here in the VT winters and I think it throws your mileage numbers off a lot. Cold weather, winter gas, etc all don't help either.

I took a 50 mi trip up along the lake two weeks ago, 50-55mph consistently, averaged 23.5mpg. All in all this truck seems to vary more than my last.

hotrodz37 · February 26, 2016

Same here, mine is bad, but like the poster above me, I am 30-40 mph stop and go and I by no means have a heavy foot. My air dam is removed, truck leveled and have 33" tires. I'm averaging 11.5-12.5 give and take the day. But I only drive 4 miles to work, and with gas prices so cheap it doesn't really bother me, but I can see if you are getting that with no mods etc I would be a little upset.

jamesonjc · February 26, 2016

I just purchased a 2015 Sierra Z71, 5.3 with 3.42 gears last month. My 2010 averaged about 16.5 all around. Winter/summer, long trips, short trips. It probably varied from 14-20.

My '15 thus far has averaged 11.5mpg around town (30-40mph stop and go). And about 16.3mpg in the last 500. I agree with the previous posts, I use the remote starter a lot up here in the VT winters and I think it throws your mileage numbers off a lot. Cold weather, winter gas, etc all don't help either.

I took a 50 mi trip up along the lake two weeks ago, 50-55mph consistently, averaged 23.5mpg. All in all this truck seems to vary more than my last.

This is basically what I am seeing with similar driving patterns.

If I drive with a light foot to work and home - my mileage in 2-4 mpg better. Otherwise, I am getting 12 on avg.