I bought the truck about 2 weeks ago and it seemed that my mileage was good, but then I installed a ts chip, oil change, and new fuel filter. It is mostly city driving but last I measured it was around 12mpg.. 4x4, stock gears, have been keeping my foot out of it. Help!

 

Do you have 4.10 or 3.55? Auto or manual? Seems silly, but do you have any fuel leaks? how long do you let it idle before driving and how long is your commute?

All these things plus the fact that we have winter fuel right now will affect your mileage.

 

^^^ what he said...are your 4x4 locked in?

 

It is auto with 3.55 gears. My commute is mostly no longer than 5 minutes and I am in and out of 4x4. I usually let it warm up for a couple of minutes. I haven't checked for a fuel leak and I don't know how/ where to look

 

For that short of a commute, with 4x4 locked in at times, winter blend fuel, and those idle times.....seems reasonable actually...


these things like to be worked... we only get 18-20 to begin with.... so idle time plus those contributing circumstances...totally believable and reasonable from my end...

 

Ok. I do keep it plugged in so it is realistically warm I think. How long should I let it warm up in the future? I'll come back if it gets any worse.. thank you very much!

 

use a timer for the block heater, some say 1-2 hours prior is plenty depending on out side temps


I don't let my engines warm up much, maybe a minute on my diesels and start driving with a light foot on everything I have owned until needle starts to move on temp gauge

 

Ok. What mpg are you normally seeing?

 

I was getting around 14 towing a fifth wheel at 7500 lbs, plus 5 people and a bunch of gear this past summer on summer fuel


I didn't drive it much this winter but went through both tanks fairly fast on the short runs I did.


have you tied removing the TS chip to see if mileage improves?

 

How much does winter fuel normally affect mpg? And I have not tried that yet. I thought it was supposed to help mpg but maybe not. I'll put it back to stock mode and see if that helps anything at all

 

Winter fuel uses additives or kerosene but the Cetane Number could be lowered which causes poor MPG on a cold engine. You can use additives to bump up the CN but too high CN isn't a good thing either.


More info


https://en.wikipedia.org/wiki/Winter_diesel_fuel


https://en.wikipedia.org/wiki/Cetane_number

 

I just recorded my mpg again and this time it came out to 8.3 mpg.. I know it should be better than that regardless. Anything I should check for? Or where to check for a fuel leak?

 

If you are trying to calculate mpg on a single tank fill up your calculations may be wrong. You will need to fill and average several fills and mpg. Some time I can get the tanks to fill to the top and some time not so much. ( how much pump pressure, how much foam, which way the truck is tilted and some time how much time I spend getting another gal or so in the tanks) If a leak most times you will smell or see it. Take a good look in the engine valley for fuel.

 

if you have a leak, there should be a puddle under the truck you can follow its path up

 

Ditto...diesel doesn't evaporate like gas...


Different fuel...but in my focus I typically loose 10%-30% of my fuel mileage I go from 28-34 mpgs down to 22-28mpgs sometimes less if I Idle longer.