i had the same mpg as you and had my tuner lean cruise tune since i am sd tune as well and wow what a diffrence it made...im seeing 19 on the hiway but your still gonna suffer with such a loose converter in town.

 

Definitely thinking of taking it back to a local tuner. I picked the truck up near Speed INC who tuned it. As far as I know, it was done on a dyno.

I do not do much stop and go driving which is why I don't think the mileage should be quite so low.

 

your right and being SD tuned the tuner can low load or lean cruise the tune to make you get way better mpg as stated above.

 

Mine gets shitty gas mileage with a 5.3L and turbo about same as yours 9mpg in the city. Most tuners just put it on the dyno and dial in the wot and dont give a **** about cruising. Gotta buy efi or hpt and learn to do it yourself.

 

Already have HPT, just need to learn how to use it.

 

i have a similar set up, mpt70 front mount, forged 6.0, 80e, 3000 stall, 3.73 gear. still running the maf though but it was going pig rich at 10 inches of vacuum, got the tune tweaked so it goes rich at around 1psi now, made a good difference in mileage for sure 2-3 mpg better. i don't baby mine at all but a tank of gas for me i could easily get 250 miles out of driving it HARD

 

Now that you have a positive direction to go with...pics of the truck!!
How do you like it?

 

If the static comp ratio was lowered to make it more boost friendly, that will kill fuel eco too. The cam you have isn't exactly mpg friendly either. Add a heavy truck, loose converter, tall gears, fat/heavy tires and rims....

 

Yea I wanna see some pics of this thing too. Sounds nice

 

haha +1 on he pics. Sounds like a sick truck.


and sounds like your tuner was playing it safe and keeping it fat. They tend to do that. Learning it yourself is the best bet for best results id say.