Maximizing LLY fuel mileage

[Uncle Wally]

Just to give a comparison as to what my fuel mileage was before John's tune.

05 LLY Crew Cab Dually - stock tires.

Loaded - light to moderate

Modifications at the time were John's 4" exhaust, Uni Air Filter, Mega Filter and Lift Pump/Fuel Pump Pickup mods. I had EFI Live at the time, but chose to leave the stock tune in it for a while.

I was pulling a two place snowmobile trailer with two snowmobiles on it and I had one snowmobile in the bed. There were three of us and our gear in the truck. We added two honda three wheelers to the trailer on the way back.

I drove from Minneapolis to Island Park Idaho in March this year. Temperatures were in the mid 40's for most of the trip out and in the low 60's for most of the trip back.

My best fuel mileage per tank - hand calculated - was 12.5. That was treating the throttle like an egg, using cruise at 60 and never letting the tack go over 2000 rpm.

My worst fuel mileage per tank - hand calculated - was 10. My personal belief is that I got a batch of marginal fuel. I didn't change my driving style much, so I don't know of any other explanation.

Unloaded - with tonneau cover - EFI Live now installed - only changes to the tune were to EGR controls. No added fuel, no altered timing.

I get my best mileage at 50-52 mph. Treating the throttle like an egg, never letting the tack over 2000 rpm even on acceleration. I can get between 16 and 18 mpg. I drove this entire tank of fuel - no wife variables on this one.

I usually don't drive that way day to day, nor does my wife. Normal driving yields a pretty consistant 14-15 mpg.

The only issue is that I spoiled my wife with the new truck, and she won't drive our gas miser car anymore. My wife drives totally different than I do even with me giving her constant grief. Her fuel miser skills have gotten better, but are still not at my level. She only understands two pedal postions: foot completely off the pedal, and the pedal all the way to floor (for both foot feed and brake pedals). With that said, it's hard to get a good fuel economy run when my wife drives. I will work on that when we head to Pittsburgh in July. That way I can actually show her what I am talking about.

Sorry for the long post, but I thought it would be good for a comparison. I installed John's tune yesterday and drove about 45 miles on it. Fuel mileage on the DIC was astonishing. I won't give numbers at this point as I need to hand calc it. You'll here from me after a couple tanks of fuel.

Waldo

[Kennedy]

Just FYI, the changes made should not have had a big impact on DIC readings, in fact, should be none at all...

[REDTRUCK05]

Are you happy getting 14-15 under normal driving conditions? U say your best milage is at 50-60 mph? That makes sense, its logic. People just dont drive that slow on the interstate in Mpls. I like to drive the speed limit 70 mph. If I do this I get between 9 and 11 mpg, pulling 5600 lbs. If I treat the pedal " like an egg shell" unloaded I can get 14 - 15 at 70 mph. If i slow it down to 60 mph ( only when I have to ) I can get 16 - 17 mpg. Do you guys really think these numbers are ok? I think not...