2013 5.3 vortec 326HP BAD MPG

[Conky Conky]

I'm having problems with my 2013 5.3 vortec 1500 z71 extended cab short box. I like the truck other then the MPG sucks iv talked to guys with 8.1 big blocks that are getting the same as me I'm only getting 12mpg on highway on a GOOD day about 10mpg on normal day and that's at 110km/h I get about 6 to 8mpg city. I can litterly watch my fuel gauge go down when in a head wind. The truck has only 30 000km. Any thoughts would be great iv tried everything thing. Only fix I found was to go back to my old 1994 chevy Silverado

[SouthernSilveradoGuy85]

Could be a dirty air filter, tire pressures not equal or tire pressures too low. Could also be how you drive it. Also cold weather will lower mpg a lot, even if you don't let it work up, it's that cold air is more dense which means more fuel is needed. Not sure what else it could be seeing that it's only a '13 with not many miles/KMs on it. Even my 98 1500 5.7 for about 11.5 in town in the summer and about 14-15 on the highway, but that's driving it pretty normally.

[Chris]

Is anything modified on it? If so it can cause a decrease

[MB2008LTZ]

I get 9-10 mpg on average with my supercharger upgrade and 33" tires.....seems to me something isn't right.

[DwayneJ]

How long have you owned the truck? Did the mileage drop on you or did you just buy it?

 

How loaded do you drive it.

Is it hilly?

Did you check tire pressure?

Did you recently replace tires, OEM LRR tires can get 10% better economy than a tire that actually grips the road.

These trucks are unbelievably heavy and a little 5.3l might get good mileage in flawed federal testing but in real life yes a truck with a bigger engine might get better mileage. Fuel use is based primarily on work done, moving air out of the way of a barn sized vehicle an accelerating it's substantial mass are the work being done. Pumping some bigger pistons up and down is a lot less work that either of the other mentioned things.

 

Displacement and RPM the things most guys blame for bad MPG have a lot less to do with them than size and weight of the vehicle and too small an engine running too low an RPM is always in high load condition causing it to get into "power enrichment" frequently which is when the engine has to run richer than 14.7:1 air fuel ratio.

 

I would get it scanned to see if there is a code even if there isn't a light.

If you find nothing amiss then clean the MAF.

After that I might consider fresh O2 sensors because to burn that much fuel and not report it as a code I suspect they could be on their way out.

[RyanbabZ71]

Need more info what modifications on truck?

 

10-12 mpg isn't good

 

I get around 11 on my 6.2 running E85 with larger tires

 

 

Ryan

[Conky Conky]

Im the original owner iv just had the short end of the stick from day one. For instance I bought the truck got a smoking deal on it paid $35 000 brand new on 60km on the odometer after I was done test driving it. They had to clear the lot for the 14s at the time I got the last z71 chevy on the lot. I had the dealer pay to put on a full custom 2 3/4inch cat back straight piped exhaust and I had a 2 3/4 inch spacer lift at all four corners and Toyo tires put on their about 3 or 3.5inches taller then the shity factory tires. But even before I did any of this it was hard on fuel from day one. Some tell me it just isn't broke in yet but I think its got to high of gears its 342s with 6spd auto. On flat level ground if I keep it in 5th on the highway at 110km/h it revs at 2grand and gets about 13mpg in 6th its 10-12 its lugs a lot in 6th. My 08 6.0 vortec 2500HD had 6spd and 373 gears and it would sit at about 13-14 highway with oversized duratracks. I'm kinda mad at my self going to smaller truck with smaller motor to get less mpg. Its not a daily driver I think I'm just going to have to except the fact that its just one of them trucks. I'll keep driving my 94 as my daily rig. Check out my you tube videos (Conky Conky)

[POS VETT]

What kind of fuel does it use? Do you warm up the truck after a cold start? Do you idle the engine regularly?

 

Raising ride height, in this case by suspension lift and larger tires, has a direct effect on aerodynamic drag which affects fuel consumption rate. The larger and heavier tires also requires more fuel to bring up to speed.

 

Several engine parameters need to be checked to draw the right conclusion. Without a proper scan tool, knowledge of how the engine works, and access to the truck, it would be hard to come up with a correct diagnosis over the internet.

[Conky Conky]

I just run regular gas in it but I want a Volant cold air intake with the scoop even if I don't gain mpg I just want the sound they make but almost everyone I talk to stand by their Volant intakes.