Thanks guys when I head back Sunday I will try some of these Ideas. I think some of it could be that stupid programmer I had loaded, we will see.

 

The fuel that you buy has a lot to do with you MPGs too !! Various States have various mandated blends of Ethanol, and also expose you to various regional distributorships that blend based on these requirements. Ten percent Ethanol may do something to reduce Smog in some big cities, but it can really knock away your MPGs (and doesn't do anything good for the price of fresh corn-on-the-cob either).
Here in AZ, the 10% blend is essentially year-round. But when I roadtrip up to Southern UT and Western CO, I can buy some "Mountain Blend" which is actually 1-2 Octane lower (Regular is 85 - Premium is 88) - even with the lower Octane and the thinner less Oxygen air I see +1 or +2 MPG.

 

Here in our area we usually have either 89 octane ethanol blend or regular unleaded at 87 octane. The 89 octane ethanol blend is around 10 cents cheaper than 87. I think that is because we have several ethanol plants around us.
There is always cussin and discussion about which is better. I have used both and I can't see a hill of beans of difference. Sometimes one is better and the other times the other is better.
I believe the main advantage of ethanol blend is that it is a renewable fuel. By that I mean it is not dependant on thousands of years developing in the earth. It can be raised every year from a variety of crops. In our area it is corn.
It would be different if we sat on an unexhaustable source of oil in the ground but we all know that isn't the case.
Now there are gas stations around that have e-85 which is 85% alchohol and they definately take a hit in mpg's but they are paying less for the fuel. If there are any of you using this I would be happy to hear the mpg's.
I guess what I'm trying to say is that I think ethanol blend is not a final answer. It is building a bridge until we can find a viable answer to get us from fossil fuels to something better. Whether it is electric or hydrogen or whatever you need something now to get us to the future.
kasjun

 

My Iowa mileage sucked too. I used 89 octane and found out that at 75mph I would get 15-16. Try slowing down. The wind killed my mpg's as well as cool temperatures.

I just drove from Iowa to New Jersey, at payload, and got 16.5 to 17 mpg. I also have 14k on the truck now.

How many miles are on your truck? It may take 5k or more to get the best mileage.

 

I have a 4X2 Laramie with the 3.92s a, 20in wheels and HEMI etc. I average between 17.8 and 18.3 in mixed driving (60% highway and 40% city). There are so many factors that enter into it but why are you using 91 octane? There's no point in using supreme and the engine isn't calibrated for it so if anything I bet that's not helping your mileage and I'd argue that it's probably hurting it by up to 1mpg. Try using 87 on the same trim and see what happens.

Jason

 

I agree, speed was prob your biggest culperit. On long cruises, I stick at 65-68 (because I'm stingy) 3.92's also hurt you a little, 91 octane may not have hurt you, but I bet it didn't help you at all. The programmer also prob hurt your econ. I'm guessing it's a performance tune, not an economy tune, right?

My 5.7 Crewcab 4X4 with 3.55's & 20" wheels will consistently give me between 20 to 21 on the highway. (At 65-68 mph that is)

 

I reset my computer when going on the highway for my long trips and if you believe it, I am getting 20, 21 mpg. I have the 4.7 and I also have a fiberglass cap and I set the cruise at 65..Joe

 

Yes it's not the economy tune, I'm leaveing from Michigan to head back to OK Sunday afternoon and did pull the program out. Gonna switch back to 89 and run 68 MPH and see what I get. I would like to at least get 18.0-18.5 I would be happy. I will let you all know Monday evening or tues. morning what my results are.

 

I got 19.1 MPG last week. I went 250 miles all freeway. I had the cruise set at 69 MPH 95 % of the time. I also had the bed loaded with a motorcycle and all kind of other **** (about 1200 pounds) I was run 87 octane costco gas.

It would have be over 20 MPG if i had not been driving thought Las Angeles and a mountain pass.

 

Winter blend gas contains alcohol to reduce emissions during the winter months. It kills your mileage by about 2-3 mpg. less bang out of canned corn then good old oil