18 MPG Highway... FINALLY!

[SHyans]

Well I seem to have finally bumped up my MPG to a respectable level. Just returned from a trip to Denver from SLC and I average a little better than 18 with cruise control at 75!

I've done so many things lately can't really attribute it to one but here are the variables:

-Drove with Attitude at #1 ("Mileage"). Bumped it up to 4 and sometimes 5 in passing situations.

-Added Power Services Diesel Fuel Supplement each fill up.

-315's @ 50 PSI

-AFE Stage 1 PG7

-Had Reflash



What ever it was I'll take it... . Oo.

 

[Alan Reagan]

Sounds like all of the above. I don't have a box on my 3rd gen but I got 1. 5 mpg on the reflash.



On my 98 I got about 2 on a Raptor box. So every little bit helps.

 

[Marty1]

I think I got 18MPG once... going downhill with a tail wind! :-laf

 

[Vaughn MacKenzie]

SHyans 18mpg with your setup and 315s at 75 isn't too shabby



Vaughn

 

[caseyd]

You guys just make me sick!!!!

I couldn't get 18 mpg being towed down hill with a tail wind!

I get 14-14. 5 driving like grandma and around 13. 5-14 driving

normal.

 

[moel]

my last tank = 10. 0mpg - overhead and hand calc were exactly the same. i plowed snow for about 1 hour of that tank taking my average of 11. 3 down to 7. 3 and then went back to 10. 0 - have had reflash but so far my mpg's are worse. maybe they will get better with warmer weather and more miles on the engine, i hope so - i'm feeding this truck all my beer money!

 

[bpenrod]

You guys just make me sick!!!!

I couldn't get 18 mpg being towed down hill with a tail wind!

I get 14-14. 5 driving like grandma and around 13. 5-14 driving

normal.

That would make me sick! My last tank was 19 mpg hand calculated with 14 hours of running time (lots of long idle time in cold weather) and mixed driving. Do you guys running the 315's have the speedo corrected and maybe checked with a gps??

 

[caseyd]

I left my speedo calibration alone so the miles won't stack up

quiet at fast on the odometer! I just multiply my hand calculations by 1. 0881

which gives me the correct mpg.



My mpg is the same with the 315's as it was with the 235's. The 315's help

as far as the 4:10 gears go but hurt with the large surface contact.

 

[SHyans]

You guys just make me sick!!!!

I couldn't get 18 mpg being towed down hill with a tail wind!

I get 14-14. 5 driving like grandma and around 13. 5-14 driving

normal.

I wasn't either but I've been tryin' real hard to find out how to improve things. Maybe follow my lead on one or two of the things listed in my post and see if it helps. I also had the reflash done for the speedo correct.

 

[caseyd]

I wasn't either but I've been tryin' real hard to find out how to improve things. Maybe follow my lead on one or two of the things listed in my post and see if it helps. I also had the reflash done for the speedo correct.

I have had the TSB Flash already!

I use PS Silver at every fill up!

And I keep good air press in the tires.

I am running the stock air filter.

And I don't have a box! YET!!!

 

[SHyans]

I am running the stock air filter.

And I don't have a box! YET!!!

Hummmmm... ... Juice w/ Attitude, Torque Tube, Stage 1 & PG7???

 

[JVolpe]

See signature for installed mods. I have the TSB Flash. I use Power Service Kleen in every tank.



I have never averaged better than 16. 2mpg on the highway, and that was the best(tail wind all the way) and usually is around 15. 0-15. 5 mpg all highway (70-75mph). Average 13-13. 5 city driving.



I have an Edge Juice/Attitude I will install in a few days. I hope I see some mpg improvement on mileage settings. MPG was one of the factors in purchasing the Cummins.

 

[moel]

MPG was one of the factors in purchasing the Cummins.

ditto, that and the reliability and power. for $5000 extra would have been a good trade-off if i got everything i paid for without the flack from DC(always saying nothing wrong - drive it hard it will get better) i thought plowing snow and hauling wood was work!

 

[RLutkenhaus]

I took a trip from Houston to L. A. and averaged 18. 5 at 75 when I only had about 5,000 miles on my truck. I generally average 18. 5 to 20 if I keep it from 65 to 70 on the highway. I put Power Service in when it got down in the 20's to 30's and noticed a significant reduction in MPG, down to about 16 MPG. If I don't put Power Service in at the same temps, then my MPG stays up at 18. 5 to 20.

 

[bpenrod]

I'll have to pay more attention to mpg with and without additives. My last tank was with half a bottle (a little over kill) of Power Service in it. That was the one I got 19 on.

 

[RN1]

I average about 13. 5 per tank hand calc'ed no matter what I try. I had the TSB done and it went to about 15... . for a while, but then it went right back to around 13, where it has been since new. I took it on a 2K mile trip in December and returned and average of 13. 3 for the entire trip. I can drive it on the floor, or with an egg under my foot, no diffference in over 16K miles. The dealer did the injector kill test and of course, "it's normal". Even said they called Cummins and was told around 13 was good for my combination.

Robert

 

[moel]

The dealer did the injector kill test and of course, "it's normal". Even said they called Cummins and was told around 13 was good for my combination.

Robert

i got same response - if the mpg's are so good to Cummins then maybe they would like to rebate a portion of the $5000 extra paid for their engine or supply "fuel coupons" to help pay the difference between our poor mpg's and the acceptable normal of 17mpg+!

 

[RN1]

i got same response - if the mpg's are so good to Cummins then maybe they would like to rebate a portion of the $5000 extra paid for their engine or supply "fuel coupons" to help pay the difference between our poor mpg's and the acceptable normal of 17mpg+!

That's kind of what I was thinking. That would buy a lot of Gasoline, especially since it is cheaper to buy now than diesel is. However, you still wouldn't have the Cummins power or reliability. I know I have the worst possible combination for fuel mileage, but I didn't expect 13's. I would be ecstatic to get 17's out of this truck... . The dealers have to know there is such a discrepancy between trucks, just seems they don't care about it... . Robert

 

[Kennywould]

I have had the TSB Flash already!

I use PS Silver at every fill up!

And I keep good air press in the tires.

I am running the stock air filter.

And I don't have a box! YET!!!

How many miles you have on this rig???

 

[SHyans]

I was in the same boat as you guys complaining about 13mpg and it was ******* me off big time.

It's been my ultimate goal to read as much as I could on TDR about mods I can make to positively impact my mileage. The things I've listed were all done between xmas and now and ran me about $1200.

My highway mileage has conservatively jumped 3 mpg.

My city driving is usually with the Juice at a higher setting and lead-footed so I can hardly expect to see similar mpg increases city-wise.

I have 8,000 miles on this thing so I expect to see even better mpg's down the road.

By the way, these are hand calc #'s and the overhead is way off. It's max reading was 15. 7, hand calc was 17+ going and 18+ coming back.