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15MPG normal for 2014 5.3 Denali?


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I recently bought a 2014 Denali with the 5.3 4WD. 

 

Is 15MPG normal for this truck? No matter what I do it’s 15MPG. Which seems very low for a 5.3L truck. I had a 2010 Sierra with the 5.3 and I would get 18MPG mix and 22ish in the freeway. And the 5.3 feels way underpowered.

 

The truck does have a leveling kit and 33” Falken Wild peaks. Would that kill the mpg that much? 

 

Ive had a 2019 Ram 5.7 Hemi rental for the past few weeks. I am averaging 18 mix and over 20 freeway and this truck has WAY more power than my 5.3. 

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My 14 got 23 highway on the way home from the dealer. But I get 14 now with a level and the front airdam removes. Mostly city driving


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Jack it up and put on big mud tires and your fuel mileage goes to hell.  These things never get as good as fuel mileage as the window sticker says, anyway.  Especially after you have to turn AFM off.  And usually the fuel mileage is even worse if you hand calculate it, as the instant or avg fuel economy shown in the Driver Info Center display is usually programmed to be over-optimistic.  

 

Another thought is, maybe the truck was tuned and you don't know it, and if you're not running premium fuel, it's running like a dog.  

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Welcome to the Site and club Mike.

My '14 Sierra 5.3 can range anywhere from 15-19 mpg average.

I have found through the years that the slightest change in temperature, tire pressure and even gas from different stations affects my overall MPG.

Winter months can bring 12-14mpgs. Gearing is also a big factor. Do you have 3.42 , 3.23 or 3.08 ?

My truck is happiest running on E85. Shifts are smoother and not as much minor drone in V4. I do not mind the minor hit to MPGs. Trade off is well worth it for 25 more Hp/Torque.

In the winter months I run 89 as that seems to be the preferred octane for my truck.

If you have a lead foot and like to get on it now and then ( who can resist right?)  look for the average to stay closer to the 14-15 range.

Right now my average is about 17.1 in summer on E85. 

Try running a few tanks of E85 thru it if you are flex capable and have a station not far from you.

Some of These DI engines can be affected by carbon buildup and running rich with higher mileage. The Ethanol keeps exhaust soot at bay as well.

One last thought to mention..... idling often can drop the average quickly and it takes some time to build back up better average MPGs as a result.

 

 

Edited by Sierra Dan
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23 minutes ago, MaverickZ71 said:

Jack it up and put on big mud tires and your fuel mileage goes to hell.  These things never get as good as fuel mileage as the window sticker says, anyway.  Especially after you have to turn AFM off.  And usually the fuel mileage is even worse if you hand calculate it, as the instant or avg fuel economy shown in the Driver Info Center display is usually programmed to be over-optimistic.  

 

Another thought is, maybe the truck was tuned and you don't know it, and if you're not running premium fuel, it's running like a dog.  

Huh? That just isn't true...

 

Tyler

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The lift increases air resistance.

The larger tires increase both rolling resistance due to friction of the tire, and increased inertia due to weight of the tire.

Due to the larger tire, your mileage is being under-reported, so BOTH the computer's fuel economy gauge AND hand calculations are off by a few percent.

 

Use a GPS to log mileage over a tank to get a more accurate view of fuel mileage.

 

But to answer your question, no, your mileage isn't unheard of, especially with any mods.  I'm averaging 15.5 on E85 mostly around town with my '16 CCSB 4x4, my '17 DCSB Z71 with 3.42 did 22 mpg NY-FL and back, and my '14 Ram CC with the 5.7 and a 3.92 rear did the same drive at 21.  All stock trucks, doing 70-75 on the highway.  The highest my F150 FX4 Screw 5.4 could do was 16 highway, 11 around town... but that was leveled with oversized tires.

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I recently bought a 2014 Denali with the 5.3 4WD. 
 
Is 15MPG normal for this truck? No matter what I do it’s 15MPG. Which seems very low for a 5.3L truck. I had a 2010 Sierra with the 5.3 and I would get 18MPG mix and 22ish in the freeway. And the 5.3 feels way underpowered.
 
The truck does have a leveling kit and 33” Falken Wild peaks. Would that kill the mpg that much? 
 
Ive had a 2019 Ram 5.7 Hemi rental for the past few weeks. I am averaging 18 mix and over 20 freeway and this truck has WAY more power than my 5.3. 


The 33” if wider will add rolling resistance, swap them out for skinnier tires and you’ll definitely get a plus on your mpg’s. Your level won’t make that much of a difference.


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2 hours ago, Z06_Mike said:

I recently bought a 2014 Denali with the 5.3 4WD. 

 

Is 15MPG normal for this truck? No matter what I do it’s 15MPG. Which seems very low for a 5.3L truck. I had a 2010 Sierra with the 5.3 and I would get 18MPG mix and 22ish in the freeway. And the 5.3 feels way underpowered.

 

The truck does have a leveling kit and 33” Falken Wild peaks. Would that kill the mpg that much? 

 

Ive had a 2019 Ram 5.7 Hemi rental for the past few weeks. I am averaging 18 mix and over 20 freeway and this truck has WAY more power than my 5.3. 

I get the same mileage with my 16 5.3 i have my AFM disabled and 35" tires . Really depends on what transmission you have 6 or 8 speed and what rear end ratio . Also that new RAM you are driving is probably a 10 speed and has the new Hybrid system and p rated slick tires not a apples to apples comparison . 

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2 hours ago, Z06_Mike said:

I recently bought a 2014 Denali with the 5.3 4WD. 

 

Is 15MPG normal for this truck? No matter what I do it’s 15MPG. Which seems very low for a 5.3L truck. I had a 2010 Sierra with the 5.3 and I would get 18MPG mix and 22ish in the freeway. And the 5.3 feels way underpowered.

 

The truck does have a leveling kit and 33” Falken Wild peaks. Would that kill the mpg that much? 

 

Ive had a 2019 Ram 5.7 Hemi rental for the past few weeks. I am averaging 18 mix and over 20 freeway and this truck has WAY more power than my 5.3. 

Are you correcting for tire size in the mileage calcs?

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How many miles?

I recently did new plugs wires and coils chasing multiple misfires. I think what fixed my issue was the Techron Fuel injector cleaner i used.

But since i have new plugs and all, i have been getting way better MPG. Im leveled and on 33" in V8 mode only and i got 18mpg on my last tank.

Before changing all this i was getting 14-15mpg per tank. (same gas station and 87)

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Fuel mileage for my 14 Z-71 with the 5.3 is averaged at 14.5.  Thats a 20 miles commute one way to work with a combination of highway and city driving.  I have a 2" level with 275/60/R20 BFG KO2s (roughly 33" tall).  I removed my front air dam as well.  As stated previously, the larger and heavier tire will bring the mileage down quite a bit.  I run Premium fuel in that truck also.  Makes a huge difference in performance in my opinion.  

 

I believe these trucks from factory require no less than 87 octane.  So, if you're running regular unleaded (86 octane where I live, higher elevations will be less) they'll run pretty crappy.  

 

 

 

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For me with a stock 2015 DC Z71 back and forth to work I get 15-16mpg depending on the time of year.  But on my 16 mile round trip I have 13 guaranteed stops and 4 more potential stops......so I never get much more than that.  If I go on the highway, doing 75-85 I can get 20-21mpg (saw 23 once).  If it's two lane middle of no where driving, no stops I've seen 28-29 mpg doing 55-60.

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Try running a couple tanks of 89 octane.

Mine 5.3 prefers this over 87 and yields better MPG results.

93 octane does not provide me with any significant benefit over 89 either in power or even increased MPG.

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