Its just very strange when i switched to the 91 tune and 91 octane fuel she was awesome on gas now its just the ****....maybe i need to reset my pcm or something..couldnt hurt i guess

 

Yeah I could see that. With the SC on 87 it was somewhere in the 13.3 ball park and switching it to the 91 bumped it to the 14.3 range. Switching to the diablo 91 bumped it beyond that though to the mid 15 rang, then everything else upped it a bit more than that.

dunerider650 - Try resetting the PCM (pull the fuse or disconnect the battery) and then reload the 91 tune and see what that does.

 

I notice that some of you are saying you cruise at 70 mph and are getting poor mileage, my experience recently is that at 65 the mpg's are much higher than at 70.

To clarify this, in August I travelled over 400 miles with the truck full of camping gear, 4 up with bikes etc, sat at 65 on cruise all the way and reset the ave mpg before heading out, I got 21.1mpg(US) average and did nearly 450 miles on one tank.

If I travel at 70mph on cruise I get only about 17-19mpg(US).

We drive vehicles as aerodynamic as house bricks.....

 

 

I easily get 24-26 mpg on the highway..and thats averaging about 80mph. So at thw magical 65-70 mph it must be better? I recently went to University of CT and back(about 115 miles) and used not even 4 gallons or the 1/8th. I have a 32 gallon tank mind you but I easily get 700+ miles on a tank highway. I also have a quad cab long bed, and stock gearing for this high rev passes on the highway. I can easily obtain 20 on highway without even trying though. I don't have any out of the ordinary parts either.

 

24-26 with a hemi 4 door long box...........o..kk....

 

You need to stop smoking the obvious because aint no way even a 2wd reg cab dakota 6cyl 5spd is gonna get that kinda mileage. Your in CT. You got 4wd? i don't even care. Your not getting 24mpg.
Cannot go by 1/8th or 1/4 tank by looking at the gas guage...lol Cannot go by the overhead read-out either. There is a reason we all have 26gallon tanks with the optional 32gallon tank. WE OWN GAS GUZZLERS!

If you think you only used 4 gallons to travel 115miles, you must have been on full because there is always extra room past full for more gasoline. that's why the first half of fuel burns longer than the 2nd half of fuel. Full by the manufacturer is at 80% capacity. Most fill upwards of 95% where the gas is spitting back out.

Best mileage i ever recorded was 19.1 going downhill on the read-out. best mileage for all highway here in NY on 93oct was 17mpg

 

Uh yeah right. the village people think you're an idiot

 

I'm pretty sure Chrysler would advertise their trucks to get 24-26mpg if that were possible, but my window sticker says 17mpg highway. QC 1500 4x4.

 

well you guys are missing out then...why would i ever lie about my gas mileage? before headers, e-fan, ported throttle body, I was averaging 20mpg. Me dividing 700 something or 800 something on a tank by 32 will equate to the same readings I get on my gauges. I NEVER get below 20 on the highway...how about that. But I get crappy town obviously since its hard to keep it under 2k. But it dont matter to me im just saying its possible because I get it all the time.