[Skierbum]

I have an 05 lly and im getting about 12-14 hwy empty and towing really doesn't matter. Why am i getting such horrible mileage?

 

[PowerlabsTim]

my lbz sucks at stop and go mileage, how are you calculating the mileage? I wouldnt go off the factory display as they are almost always wrong

 

[Skierbum]

40 mile commute everyday with one stop the entire trip at 70mph. I hit the trip everytime i fill up (all the way to the top). Then devie miles by gallons when i fill up the next time. My old man got efi from you guys awhile ago, so I may be switching to efi if his just that much better than mine.

 

[Skierbum]

DIC is also say 25mpgs, so I know its lying to me.

 

[PowerlabsTim]

what mods do you have with the LLY?

My dads o5 has our tow tune , 4" exhaust, bullydog intake, LBZ mouth piece and i got 16.5 towing our flatbed dovetail trailer to colorado empty and about 14 on the way back with my lbz on it

 

[Skierbum]

5inch downpipe back, lbz mouthpiece, edge evo race,and egr delete

 

[PowerlabsTim]

what tune do you normally run on?, how many miles on the truck? size of tires?

 

[Skierbum]

160k on the truck, 285s, and level 3 when not towing, level 2 when towing.

 

[PowerlabsTim]

have you tried different tunes when running empty, some trucks like the higher ones others like lower, speedo corrected for the tires?

 

[Skierbum]

speedo is adjusted pretty good for the tires but could be better and havent tried any higher tunes because i dont have a lift pump or a tranny

 

[PowerlabsTim]

try the higher ones and keep your foot out of it see if mileage changes

 

[azDirtyMax]

I have the same truck and the edge will give you better milage with it in 5 or 6 with the cruse set just don't beat on it! EFI LIVE changed my milage greatly I get 18-19 on the freeway and I have 35s

 

[054x4dmax]

i get 20.4 mpg on 305-45-22's with mods in sig on level 4

 

[GreyGhost82]

Not sure if this is good but according to the truck i'm getting high 16's to low 17's to and from work (about 53 miles total 38ish 55-60mph highway the rest is city with lots of stoplight waiting in afternoon). Stock tuning that I know of, I am running stanadyne about every other fill up. I do tend to baby it but there are those moments :gearjamin

gonna start using my gas cubby iPhone app again and do self calculations for my MPG to see if what I have been going off is right or not

 

[Rubberdown Customs]

I have the same truck and the edge will give you better milage with it in 5 or 6 with the cruse set just don't beat on it! EFI LIVE changed my milage greatly I get 18-19 on the freeway and I have 35s

Hmmm, I got the same truck too, I'm running a 6" lift, 35" tires and I just added the MBRP 4" duals from the down pipe back, and added a cold air intake and I only get 13 MPG empty with mixed hwy and city driving, and I do not hammer it, I try to keep the tack at 1800 or 1900 on the hwy so thats around 115 KPH. The sad thing is this truck has an EFI Live tune from about 3 years ago from the original owner, but its going back in for the EGR Delete and maybe an upgraded tune to try and improve it.

 

[JD32]

Hmmm, I got the same truck too, I'm running a 6" lift, 35" tires and I just added the MBRP 4" duals from the down pipe back, and added a cold air intake and I only get 13 MPG empty with mixed hwy and city driving, and I do not hammer it, I try to keep the tack at 1800 or 1900 on the hwy so thats around 115 KPH. The sad thing is this truck has an EFI Live tune from about 3 years ago from the original owner, but its going back in for the EGR Delete and maybe an upgraded tune to try and improve it.

A lift changes alot, now your playing with aerodynamics and a lift doesn't work in your favor, 35's aren't helping either, 13's a tad low but for a mix of city and freeway it far off, but with a new tune optimized for your setup you might get a tad better but don't expect to much, dont trust the DIC, hand calculate it if you already aren't

 

[Rubberdown Customs]

A lift changes alot, now your playing with aerodynamics and a lift doesn't work in your favor, 35's aren't helping either, 13's a tad low but for a mix of city and freeway it far off, but with a new tune optimized for your setup you might get a tad better but don't expect to much, dont trust the DIC, hand calculate it if you already aren't

Thanks, I know the lift and tires are working against me, but I figured a diesel would get better mileage than my 08 F150 got LOL. The mileage wasnt really any better before the lift, if it was at all better, it wasnt enough to really notice it at all haha. And ya, I calculated it myself, and I added the miles that the larger tires didnt get accounted for on the trip meter. The DIC says I'm at around 19 mpg, but by hand calculations I am at just a hair over 13 MPG.

And the error with the tires in the speedo is about 6% if I figured it right, 100 KPH on my speedo is around 106 on my GPS, so 450 KM/tank is really about 477 KM/tank and with an 85 liter tank, it works out to around 13 mpg.....right?

 

[JD32]

Thanks, I know the lift and tires are working against me, but I figured a diesel would get better mileage than my 08 F150 got LOL. The mileage wasnt really any better before the lift, if it was at all better, it wasnt enough to really notice it at all haha. And ya, I calculated it myself, and I added the miles that the larger tires didnt get accounted for on the trip meter. The DIC says I'm at around 19 mpg, but by hand calculations I am at just a hair over 13 MPG.

And the error with the tires in the speedo is about 6% if I figured it right, 100 KPH on my speedo is around 106 on my GPS, so 450 KM/tank is really about 477 KM/tank and with an 85 liter tank, it works out to around 13 mpg.....right?

Well i dont use kilometers but it sounds like you have an error in there somewhere, go to the dealer or when you get your truck tuned make sure to get your speedo corrected... How are you calculating it? the easiest is to fill ALL the way up, reset the trip, run it down and fill it ALL the way back up and divide the gallons by the miles. Are you trying to account for the whole tank?

 

[azDirtyMax]

Hmmm, I got the same truck too, I'm running a 6" lift, 35" tires and I just added the MBRP 4" duals from the down pipe back, and added a cold air intake and I only get 13 MPG empty with mixed hwy and city driving, and I do not hammer it, I try to keep the tack at 1800 or 1900 on the hwy so thats around 115 KPH. The sad thing is this truck has an EFI Live tune from about 3 years ago from the original owner, but its going back in for the EGR Delete and maybe an upgraded tune to try and improve it.

wow thats too bad mine got 14 mpg with the lift and tires before any mods lol so you might wanna get that checked out after everything about 18mpg calculated and if your going off the dash reading and your speedo isn't recalibrated thats way off because your trucks not going as far as it thinks. you have to take your miles by the gallons to figure it out right!

 

[Rubberdown Customs]

Well i dont use kilometers but it sounds like you have an error in there somewhere, go to the dealer or when you get your truck tuned make sure to get your speedo corrected... How are you calculating it? the easiest is to fill ALL the way up, reset the trip, run it down and fill it ALL the way back up and divide the gallons by the miles. Are you trying to account for the whole tank?

Ya, I converted the liters to gallons and the kilometers to miles and I reset the trip on every fill up and run it till the low fuel message comes on. At that point I fill up and the 85 liter tank usually takes about 82 liters to fill it. I resent the trip and do it all over again, every single fill up.

I hope when the guy tuning it for me mentioned adjusting for the larger tires he meant he was going to adjust the speedo to the new size of tires. I go see him this friday.

Sorry to highjack the original posters thread, maybe he too can gain some insight from my questions too...