i have a 99 reg cab lwb 4x4 cummins 4 in lift 35 in mts on it and went on a trip today mostly highway miles and averaged out at 11 mpg mods to my truck include
4in exhaust turbo back(straight pipe)
edge juice with additude programmer (i had the programmer on the mileage setting)
not sure if injectors have ever been replaced
i put a lift pump on a month ago it runs at 15psi idle and round 12psi going down the highway
changed the fuel filter when i put the lp
on factory air box
any ideas on what could be the problem??

 

what speed were you running down the road?

 

I was running between 65 an 70 right at 2 grand on the rpms

 

for some reason i get better fuel mileage between 70-75 then i do between 65-70. not a heck of a lot maybe a mile or two. whats your air cleaner look like? i was having an issue with mileage a month or two ago after driving a lot in the desert when it was dusty. it dropped down to around 15 from 20-21. I did a full filter service and it shot my mileage back up (air,oil,fuel). i noticed that if I am getting closer to 5000 on an oil change i loose about 1 mpg highway too. try hosing out your intercooler/radiator. idk where your from but a lot of debris in there can limit the effectiveness of your intercooler too. might sound weird but it works in my truck.

 

i get my best fuel mileage with the juice set on level 5. most of the guys around here do to i believe.. try that and see how it works for ya.. also i have my settings all on 5 too
1x5
2x5
3x5
4x5
5x5

 

Really 5 with the fuel up ? I'm been debating on going to a bhaf

 

i drove mine with it on economy for a while and didnt really notice a gain so talked to one of the guys on here he said try the level 5 i did and i average anywhere from 18-22mpg depending on how you drive it..If you get in it and blow smoke all the time then this above wont happen either, i romp it every now and again but mainly 60-65mph I am also running a smaller tire than what you are a 285/75/16, the bhaf is a good cheap filter cheaper than the rest that is. I have been happy with mine so far

 

Could u tell a mpg diff in it ?

 

in the bhaf??? maybe a little, i put it on after i already had the edge on and my airdog 150 that is what i would say helped me the most and then the addition of the bhaf

 

I plan on doing the bhaf and cleaning the map and iat sensors in the next few days the truck has a new lp or I would upgrade to the air dog system