LBZ: Mileage issues

[Timmay208]

Truck is a 06 LLY with LBZ flash 12606128
s&b intake
egr block plate and turned off
DE downpipe
4"
pcv re routed
amsoil fuel additives every tank

seems like no matter what i can do i can only squeeze 13-16mpg out of the truck, 265/75 tires on stock wheels, on hwy i always set cruise around 70-73 1800-1900 rpm
Tried a few different tunes but just not having luck, i know alot of guys with lbz guys easily getting 17-20 with mostly hwy, my last all hwy tank was like 15.8 hand calc
Speedo is dead on with GPS
Truck does have 205k miles but it runs pretty smooth has plenty of power, balance rates on injectors are all close and low #

I just dont really know what else to do or try, been debating getting a tune from nick@duramax tuner or rob but just dont wanna spend bunch of extra money on tunes and not even know if its gonna help the mileage

maybe the motor is tired?, turbo has minimal play, i keep up on all my fluids, doesnt smoke or anything and im very easy on the throttle

I know i cant expect mileage of a car or anything but with fuel prices being 4$ a gallon even 2 more mpg would help a ton, i always see guys claiming 24 + but i just think that is complete BS

any suggestions would be greatly appreciated

 

[JoshH]

Do you have a stock tune or what? When you say all highway, do you mean you fueled up, got on the highway and didn't stop again until you needed more fuel?

 

[Timmay208]

yea filled up got on hwy to where i was going and filled back up

ive tried a 80hp tow tune, then another " mileage" tune from one of the tune librarys and then stock tune

so far the 80hp tow tune has been the best

 

[DMAXDOC]

My LBZ gets 15.5 consistently hand calculated But, It has 37s on it

 

[Timmay208]

yea with 37's i wouldnt feel to bad but on 265's all hwy i think 17-19 should be possible

 

[N_White04076]

Mileage

I drove my truck to Florida with Josh H's race tune he has on this site and averaged 19.5-20mpg all highway. I can easily get 17.5 mixed driving if I stay out of the throttle. Florida trip I had 265's on the truck, this summer I had 245's on, getting sick of buying expensive tires just to by new sets for the rear HAHAHA

 

[dirty-b]

I'm with ya on the MPG. Although mine is a lb7 I have not gotten better than 16 MPG. That's driving to the cabin and home at 63mph 1800rpm trying to get good mileage and filing up when I get home. About 270 mile round trip.

 

[Timmay208]

i know the higher elevation here isnt helping but my old man has a 05 and my uncle has a 06 like mine both of them get 18-19 hwy empty with ease, just leads me to think there is another issue

 

[02greysixer]

A friend of mine has an lly that has the same problem, it only gets like 14-15mpg and he drives super easy. Leaves his diablo on the 80hp tune too. Someone told him it was because he had a bad FPR, don't know how true that is though. I'm sure his regulator is bad because he's got a bad loping idle but I don't know how that ties into fuel economy. Everyone else I know, including me, with a Duramax gets 18-20mpg with 35" tires.


Sint frum tha orijinul smert fone

 

[DAVe3283]

Yeah, you should be able to do better. A more powerful tune may help (extra timing & fuel pressure). I get ~18 MPG at 70 MPH on 35" tires. However, it drops to 16 if I go 80 MPH. I got no better than 16 on the stock tune and smaller tires.

 

[jevanb]

I get 16-18 in the interstate and I have pizza cutter stock size 235, I always run 67MPH and start easy, the other day I was pulling a empty flat trailer around 1.5k and was getting 14 when I pull the TT 9500lbs I always get 9-11 and I never go over 65. My truck has always been a turd in the mileage department, the 04hd gaser 6.0 got the same fuel MPG as this truck but out pulls it night and day.so.....btw I always have a topper level with the cab on