Better MPG in TOW/HAUL??

[BlackBioBurner]

I am playing around with my new truck and still on it's first tank of gas? It seems like my gas mileage is slightly better when I have the TOW/HAUL option turned on. I thought this just changed the shift points but it seems like it is doing a bit more, maybe changing something in the fuel system or injectors? You guys know much about using this option on the truck? Can you drive in this mode all the time? Maybe my larger/heavier tires and wheels make the tow/haul option a good choice for constant driving.

 

[WD40]

I have tried it both ways and seams to do better with it off

 

[bushpilot]

Im w/ Doug on this one...the main thing that changes is
the shift points <less slipping>...the rpms are held HIGHER
before each shift point & the shifts are more FIRM.

additionally the transmission aides in slowing down by
forcing some engine braking.

 

[Kleetus]

probably has something to do with the torque converter locking up and staying hooked in longer before it unlocks and flairs up 500 rpm before anything starts happening...

 

[no-red 6 0]

you must be lucky. cause my mileage goes in the toilet w/ the T/H mode on..

 

[kenholl]

I am playing around with my new truck and still on it's first tank of gas? It seems like my gas mileage is slightly better when I have the TOW/HAUL option turned on. I thought this just changed the shift points but it seems like it is doing a bit more, maybe changing something in the fuel system or injectors? You guys know much about using this option on the truck? Can you drive in this mode all the time? Maybe my larger/heavier tires and wheels make the tow/haul option a good choice for constant driving.

It may just be me, but I don't follow you. How much could you learn about your MPGs while on your first ever tank of fuel? I would think you would need a full tank of fuel under each condition to get a valid measure. Watching you MPG gauge fluctuate after you press the T/H button doesn't sound very accurate.

Is it just me?

 

[DaveBen]

Don't take any mileage too seriously if you don't have at least 8,000 to 10,000 miles. These trucks take a while to break in.

Dave

 

[bushpilot]

I am playing around with my new truck and still on it's first tank of gas? It seems like my gas mileage is slightly better when I have the TOW/HAUL option turned on. I thought this just changed the shift points but it seems like it is doing a bit more, maybe changing something in the fuel system or injectors? You guys know much about using this option on the truck? Can you drive in this mode all the time? Maybe my larger/heavier tires and wheels make the tow/haul option a good choice for constant driving.

1st off its "fuel" not gas
2nd youre not gonna get better mpg in tow haul (it holds the shift points til considerably higher rpms and
it forces downshifting...which again will increase rpms...the higher your rpms & the longer you hold the rpms
higher the more fuel youll burn)
3rd the tow/haul doesnt change anything about the injections or fuel system, it will however change the
egr & vgt positioning to increase BACKPRESSURE.

Tow haul also <in my experiance> also tends to hold the converter lockup a TINY bit longer...reducing
<by a small amount> the locking/unlocking that can be encountered when cruising the interstate.

4th you CAN drive in the tow mode all the time...it wont necessarily be fun but you can do it.

what size are those tires...20's ? are they e-rated (check the sidewall)...there are plenty
on this forum w/ 20's and bigger...NO ONE has <ever> reported better mpg when running in
tow haul mode.

Don't take any mileage too seriously if you don't have at least 8,000 to 10,000 miles. These trucks take a while to break in.

Dave

dave fwiw hes got 39k+ on that truck.

 

[BlackBioBurner]

Thank you o wise bushpilot.
I was under the assumption I was getting better mileage in Tow/Haul because I make the same 40 mile trip weekly, every time before I leave I reset the avg mpg on my console. When Tow/Haul was on I would get 1-2 mpg better than with it off. After doing this a few times I feel that the better mileage is because of the long down hill stretch of the trip and the engine braking/Backpressure advantage.
Thanks for all the imput. This was just a curious observaiton.

 

[bushpilot]

if you DONT run it in tow/haul itll "free wheel" on down hill slopes