New guy with questions

[Brandon32689]

Hey guys, I have a 2014 gmc Sierra with the 5.3, when I bought this truck I was not towing anything. Know I'm towing a 18' trailer and 2 rzr. Well gas mileage is horrrrrrible to say the least. I know it's a pretty heavy load but can't be to bad I'm averaging 8mpg at best. I've only had truck 6 months so I don't want to trade it in just yet. Build sheet says gear ratio is 3.42 it is the 2wd z71 package.

 

My question is what can I do for better gas mileage? Intake and exhaust ? Thanks

[00Silverado4x4]

How many miles are on the truck. When my truck was new my mileage steadily increased for the first 10k miles or so. You may just need to let it get some more miles to get used to your driving habits.

[Brandon32689]

Just hit 12k

 

 

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[beerguy214]

That is not good at all.I would contact a dealer snd tell them what you are towing and your average miles per gallon and see what they say.They will probably tell you to bring it in.Sorry I couldn't help but I have a ram and when I tow are 30' trailer it weighs 7300 lbs dry I usually average 12 to 13

[Sooperdave]

Hey guys, I have a 2014 gmc Sierra with the 5.3, when I bought this truck I was not towing anything. Know I'm towing a 18' trailer and 2 rzr. Well gas mileage is horrrrrrible to say the least. I know it's a pretty heavy load but can't be to bad I'm averaging 8mpg at best. I've only had truck 6 months so I don't want to trade it in just yet. Build sheet says gear ratio is 3.42 it is the 2wd z71 package.

 

My question is what can I do for better gas mileage? Intake and exhaust ? Thanks

How fast were you going? Any kind of windy conditions? How much total weight do you think you were pulling? Enclosed trailer or open? I'm not really sure what "2 rzr" mean.. Give us a few more details so we can see exactly the conditions were.

[Brandon32689]

 

Speed limit 75mph in tow hall

 

 

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[CL8N]

Tow hall prevents from shifting into 6th gear, doesn't it? Does it need to be in tow hall mode when on the freeway?

[Brandon32689]

Tow hall prevents from shifting into 6th gear, doesn't it? Does it need to be in tow hall mode when on the freeway?

Idk man that's why I'm asking you guys, I figured it did with the trailer,

 

If I had to guess weight 1500 pounds each rzr plus trailer

 

 

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[CL8N]

I don't really tow anything, but from my understanding of the Tow/Haul function, you only need it like in town or in the hills when you don't want the truck to shift as often and hold gears longer. Once you're on the freeway, you shouldn't need the Tow/Haul function, as it prevents the truck from shifting to overdrive, which would negatively impact gas mileage.

[Kuff]

With my 4x4 Z71 5.3L crew cab shortbox, I average around 10-11 mpg going 70 mph pulling a 25 foot (28 feet with tongue) travel trailer that weighs around 6500 lbs. That is a mix of flat and moderate hills.

 

Have you increased the air pressure in your tires when towing? As well regular gas or e85? 8-9 mpg does seem a bit low considering you are not pulling a big box through the air like I am.

[Sooperdave]

When you break the 70mph barrier mpg starts to tank pretty quickly. That's not much weight.. website says about 1200 lbs dry weight each plus your trailer. I towed 3500lb's on a 200mile trip and averaged 13mpg running 65-70mph. This is with the 6.2L and 3.73 gear. Gas mileage didn't change whether in 5th or 6th so I doubt that is the issue. I'd say you should have been around 10-11 minimum with heavy foot. What is your typical mpg without trailer? If you get less than 17 then I'd say either an issue or just pedal mashing! LOL

[Jon A]

Tow hall prevents from shifting into 6th gear, doesn't it? Does it need to be in tow hall mode when on the freeway?

 

Tow/Haul will allow 6th gear, you just need to be going over a certain speed at light enough throttle. In many cases you'll never get there if you don't go fast enough or need too much throttle to maintain speed. This can be changed with a tune of course. As mentioned above, the main thing affecting mileage is how much you have your foot in the throttle (hills and speed are the killers) regardless of gear.

 

Tow/Haul also changes your downshifting which you may find useful when you aren't using cruise to activate grade braking--it downshifts sooner, especially when you apply the brakes to help braking.

 

I think speed is your big killer. I towed a 6000 lb trailer about 150 miles last weekend with over 1000 lbs of cargo and was getting 12.5 in moderately hilly terrain, averaging about 65 MPH. That's with a 6.2, 3.42 gears with 34" tires.