Best tune to gain mileage in '05 Cummins

[mmperfdiesel]

What tune do other folks use to gain MPG. I loaded the Performance tune and filled the truck, drove 160 miles with the cruise set on the e-way at 70 mph then filled tank back up. Exactly 10 gallons of fuel. The truck gets 18 bone stock.

[mikel]

Usually the high power tunes get good mileage for people when driven with a light foot due to the extra timing in those tunes.

[mmperfdiesel]

I loaded the Extreme tune in it and ran the e-way with cruise set at 70 for 300 miles and then 2 lane road with cruise set at 60 for another 150 miles and it still gets 16 mpg. Why would mileage be worse with a tuner than without. Just FYI, I also tried a BullyDog GT and it did the same thing.

[mikel]

Are you calculating mileage or looking at the readout in the truck?

[mmperfdiesel]

Calculating it by hand. Last tank 478 miles 30 gallons to refill. The digital readout is all out of whack with the Trinity. It reads avg mpg at 30.3.

[David48]

I use the Performance tune and get a calculated 24 mpg (Imperial Gallon not US Gallon) which I think works out to around 20 mpg US. The truck has a free flow exhaust, Injen Air Cleaner system and a Wilson Manifold elbow...fairly standard modifications. This is not a one off mileage claim as I consistently get this when cruising empty at highway speeds.

[mmperfdiesel]

I have determined that someting is causing the truck to overfuel. My engine oil used to stay pretty clean but since I tried tuners, it is very black soon after changing the oil and it blows a lot of black smoke out the pipe even with minimal pedal and on tow tune settings. I am trying to determine if I have an injector that can't handle the extra rail pressure.

Any suggestions??

[helipain]

I have determined that someting is causing the truck to overfuel. My engine oil used to stay pretty clean but since I tried tuners, it is very black soon after changing the oil and it blows a lot of black smoke out the pipe even with minimal pedal and on tow tune settings. I am trying to determine if I have an injector that can't handle the extra rail pressure.

Any suggestions??

not sure how black your oil is but diesel oil normally turns dark even after a few miles of driving. as far as the black smoke, i get it anytime i load the engine just enough to avoid making the truck downahift (in all tunes also). if i let the rpms stay smooth with acceleration i dont get it much at all.

if you are getting black smoke all the time (cruising speed under minimal load) then i would be investigating. hung open injectors are no good on the high psi common rail trucks. 26k psi is especially bad if you have poor filtration and dirty fuel. these programmers dump the fuel iin for sure.