Fuel mpg lly???

[moorekh]

I've got a 04.5 LLY w/ a cold air intake, EFI live, and straight exhaust. I just filled the tank for the first time and it got 13mpg. It was about 50/50 hwy and city. I'm a former Dodge owner and I had a 04 ton 6spd. w/ 35s & 80hp injectors that got 19-20. I've changed all fluids and fuel filter, is this what I should expect? If so I hate to say it but I'm going back to a Dodge Hell my 03 2500 4x4 6.0 Chevy got better than that w/ 20's and heavy ass ATZ's

 

[moorekh]

I'm going to get the truck re-tuned before I sell it tho. I dont know who did the tuning but it's got a gay lope tune now. I HATE that! It's like buying a V6 Camaro or Mustang! Why be all bark and no bite? If the truck had a cam, yes it should lope. If not there is NO reason to act like it's badder than it is! (sorry pet peeve of mine!)

 

[Turbo Performance]

I've got a 04.5 LLY w/ a cold air intake, EFI live, and straight exhaust. I just filled the tank for the first time and it got 13mpg. It was about 50/50 hwy and city. I'm a former Dodge owner and I had a 04 ton 6spd. w/ 35s & 80hp injectors that got 19-20. I've changed all fluids and fuel filter, is this what I should expect? If so I hate to say it but I'm going back to a Dodge Hell my 03 2500 4x4 6.0 Chevy got better than that w/ 20's and heavy ass ATZ's

Tuning plays a BIG part in mileage. I would be playing with that as you can pick up or lose a big chunk. In my opinion your Duramax should be comparable in mileage to your Dodge.

 

[moorekh]

thats what I thought. I haven't added for tire size ratio yet but the tuning was done when the tires and wheels were on it. I would assume the tuner would have changed that. If I calc. that diff. out it bumps it to like 16. Thats still not gonna cut it. I thought I should see atleast 18 out of this lighter truck. I understand it's a V8 but are they THAT fuel hungry! The reason I own it over a BBC is for fuel mileage. I've got a buddy who has my truck in an 8.1 and he gets 12 about NO matter what! I can buy ALOT of gas for the few $k extra this dura cost!

 

[Turbo Performance]

Like I said in my first post, tuning can make all the difference. My LLY gets 15ish in town with a lead foot and 19-20 hwy at 80-85mph. That's on my own tune, I could probably get more mileage from a reputable tuner. I wouldn't sell the truck off until you try some other tuning.

 

[05' Ditry Duramax]

It's all in the tune. I get 18-19 with my truck on the milage tune running 75MPH down the freeway. That's what it says on the DTC, i've never hand calculated it though.

 

[moorekh]

Yeah and mine says it gets 18.5 on the DTC. Those are never right.

 

[LBZ]

Go to the Dieselplace.com and check out the tuning library. I believe it's cit1991 that has some really good mileage tunes over there.

Or you can play around yourself and find something that works better.

 

[moorekh]

thanks for the info! I'll have whoever tunes it check those out!

 

[Redbowties88]

my lly gets 17-18 in town with a lead foot...and i 19ish on the highway for extended periods i have gotten 20+ on occasion


hand calculated

 

[moorekh]

do you have a tune or stock? Is that a true hand calc. number w/ tire size correct?

 

[othrgrl]

Why not just buy EFI Live and tune it yourself so that you know what is done to the tuning. You can add a DSP5 switch so you can switch between tunes while driving too. I have LLYs that get 20mpg mostly city mixed driving and 25+ on the highway - ChevyDieselLLY here is one of them. Even with the heavier rims and tires you should be able to get 17-18 city and 20+ highway - that's what my truck gets if I drive it sensibly with the 20s on it.

 

[Redbowties88]

do you have a tune or stock? Is that a true hand calc. number w/ tire size correct?

with a superchip mileage tune...stock i was 15-16 city and 18ish highway


i think that tune is really hurting you....tune it back to stock you should see an increase then buy a decent efi tune


hand calculated

 

[zfuller123]

I see posts of people staitng MPG numbers, but only one says it's calculated by hand and another says it's off the DTC which are not ever very accurate int he trucks i've seen....

The other posts don't specify alot- like the truck and if the mileage is hand calculated or not. I'm just curious....

My truck, even before the motor build, twins etc. was stretching to get 14.5 mpg with stock wheels and tires - but its also over 8000 pounds before i crawl into it.

I have a tune now, for mileage - with the bigger injectors, twins, etc etc - and the best i can get at avg. 70 mph highway is 15.3. I don't know if i'm just missing something in the tuning - or if thats really all i can get.

All my #s are calculated by hand - i know the odometer is correct -verified speeds with GPS etc... so i know my mileage reading from the truck is accurate... I just don't see where i'm losing mileage - and have been since it was brand new.

I've tried all sorts of things for mileage. I even have a dsp5 to flip through to try different timing, boost levels, etc etc.... i just can't get it up even close to some of the #s i see people talking about over and over - so i'm curious how they arrive at their #s - not bashing or anything else - just wanting to know and maybe even pick up some pointers?

 

[moorekh]

Why not just buy EFI Live and tune it yourself so that you know what is done to the tuning. You can add a DSP5 switch so you can switch between tunes while driving too. I have LLYs that get 20mpg mostly city mixed driving and 25+ on the highway - ChevyDieselLLY here is one of them. Even with the heavier rims and tires you should be able to get 17-18 city and 20+ highway - that's what my truck gets if I drive it sensibly with the 20s on it.

This is probably a stupid question but...

Could you get me a copy of the tune used on his truck? I'm going to have another member here put the tunes on my truck. I would buy EFI live but I hate to spend the $700 and then screw up my truck on top of that! lol

 

[luklaus]

mpg

I hope I'm in the right section to post this question. Anyway here goes, I bought this truck brand new, it's a 2007 and 1/2 new body with dpt. I removed the dpt and the cat and installed a 4 inch system from turbo back. I then bought a quadzilla tuner and installed the +50hp tune with no dpt. My mileage went from 13.5 to 19 right away and this is actual..hand caculated. I'm a very happy camper now and just love it. Then I bought some bigger tires and had to change the ratio on the quadzilla tuner for speedo to work right. It askes for tire hieght which is 32 inches now. After re-doing the tune with bigger tires NOW I get 14mpg no mater what. I've tried the econo no dpt tune and it didn't help(power was less) but mileage stayed at about 14mpg. Then I returned the vehicle to stock. After that it sets codes for emmissions(I knew that). Then re-tuned it to the +50hp no dpt tune which is what they tell me is best for mileage, but it didn't help. It's wierd. Do I need to take it to dealer to return it to real STOCK again and then try the quadzilla again. I know it can get 19mpg because it did before and worked fine for months??

 

[luklaus]

I've been told that winter blend diesel will make you get less mileage

 

[MEANMAX]

Go to the Dieselplace.com and check out the tuning library. I believe it's cit1991 that has some really good mileage tunes over there.

Or you can play around yourself and find something that works better.

I just adapted cit1991's 80hp econotune for the dsp 2.Took a trip to Oneonta NY,got 19mpg hand caculated.

 

[Chris611]

I just adapted cit1991's 80hp econotune for the dsp 2.Took a trip to Oneonta NY,got 19mpg hand caculated.

What speed was this at and what size tires do you have?

Thanks

 

[MEANMAX]

What speed was this at and what size tires do you have?

Thanks

65-70 mph,265-16's.