Engine/Transmission (1998.5 - 2002) Fuel Mileage Average with 4.10 Gears

[Hollywud]

OK... . I'm ashamed to admit it but at 85,000 miles, I recently began tracking my fuel mileage (did it for a few tank fulls when new but, never did it again... until now).



After calculating mpg for (1) tank full, I was shocked!!! ONLY 13 MPG??? Before I completely flip out and start changing/checking sensors and the like, could someone give me a good winter/summer baseline? I am running over-sized tires (see profile) and 4. 10 gears. Anyone out there running a similar set-up that could give me some average baseline numbers?



Is this normal???... . I kinda expected more!



... the only other variable I can think of that I've added into the equation is religious use of Power Service fuel additive (Diesel Fuel Supplement +Cetane Boost) during winter months. Also, 90% of my driving is 60% highway / 40% city with no trailer in tow.



TIA!



jon

 

[RustyJC]

I get around 15-16 in suburban stop-and-go driving (35-50 MPH with a light every mile or two) on the NW outskirts of Houston. About 9. 5 to 10. 5 towing our 13,500 lb 5th wheel on the highway in the Texas Hill Country with some intermittent urban driving (like through Austin, TX). I've never run a full tank through it on the Interstate without a trailer, so I don't know what it would do there. Winter..... what's that??? Sorry I couldn't be more help...



Rusty

 

[jtwcummins]

7yrs plus average

13. 7 in town

18. 9 hiway unloaded typical 70 MPH

Drops fast on hiway as speed increases above 70.



4. 10 is good for towing, but you pay every mile!

 

[JDougherty]

I know i dont have 4. 10s but i average about 15mpg with empty doing city and hwy driving.

 

[BigDaddy]

13 MPG

Not bad, depending, on what you have for mods and how heavy your foot is



With BD 5s and the COMP on 1x1, I typicaly see 13. 5 to 14. 0 MPG on the highway with winter fuel.



This improves to a solid 15. 5 MPG with summer fuel @ 75 MPH. I don't even bother checking the around town MPG



Joe



Y2K w/89% DTT & 4. 10s

 

[Hollywud]

Thanks for the quick response, guys!!!... from what I hear so far, I'm not too alarmed (thought I might have had a problem developing). I will trend my mileage over the next few tanks and see what the curve looks like.





jtwcummins,



The mileage numbers you quoted... was that with your Banks system installed?



I've been looking at installing a Banks system because it's a SYSTEM and I don't want to experiment with a truck I rely on for daily activities. Could you comment on your experiences with the Banks system?... how did fuel mileage trend before and after (get better?)?





BTW... this is my first diesel and I really regret making the decision on 4. 10 gears. My original reason for the gear selection?... I knew I would eventually over-size the tires. Without doing any math or realizing how the torque curve would really feel , I just assumed that larger tires = low ratio required. Now that I really now how the torque curve feels, I really wished I stayed with the standard gearing. Oh well... . thought of swapping and installing a locker up front (while I'm at it) but, it's not in my present budget. Now I need to justify my savings in fuel and maybe I can make myself believe swaping now will help in the long run... haa... haa





Thanks!



jon

 

[Turbo Tim 1]

I record every tank full and over 90,000 miles I've gotten an average of just over 15 mpg with a best of 19 and a worst of 11. 5, I plow snow and tow some and my worst mileage has been during snow storms. Most of my driving is interstate which actually kills my mileage because I cruise at 73-75 mph. When I got 19 mpg I never broke 65 mph for the whole tank

 

[Hollywud]

By the way.....



My shoes do have LEAD in them!!!!!!!... ... I drive my truck like a road racer 75% of the time (heal-toe down shifts included)!



I guess that's a big variable I forgot to mention

 

[StakeMan]

If you have oversized tires it will throw the figures off if you do not compensate for it.



I have an auto with 4. 10 gears and 285 BFG's. I averaged 16. 9 on winter blend and 17. 7 now on summer. All in town.

 

[jtwcummins]

hollywud:



My average went up about . 5 in town and 1 on the hiway after banks. The first tank after the banks was under 10mpg, I then started leaving lead right shoe home. Most of the increase was because I tossed the EGR and ran a 2" speed bit thru the CAT until hollow. The EGR for the Calif trucks would turn on full at all but WOT when temp hit 140*. There was so much soot in the intake the vac line to turbo was blocked, had to vacuum it out with shopvac.



The big difference is towing, almost 4mpg more.

I did the install myself in 3 steps.

1- Blocked the EGR, got heavy black smoke off idle w/light pedal. Ran for a week.

2- Installed ATS exhaust manifold, Banks brake, Turbo housing, CAT back exhaust, and AFE filter. Ran 2 weeks no change to fueling and smoke gone completely, ain't air wonderful? Engine idled and ran alot smoother and the Banks brake cut the exhaust noise in the cab so much it took awhile to realize engine was running. At 70 on freeway was very quiet.



3- Installed plate at stock position, stock auto so being careful, and Twin RAM intake. Swapped valve springs, replaced them all w/60 lb springs and connected everything and started using brake.



When getting on the freeway, here it is parallel parking at 80, use to be a challenge because acceleration was flat until speed really built up. Now there is no flat spot. I am going to do injectors and play with ATS and plate after DTT work to transmission.



The Cummins just sounds so much heathier, idle isn't as clattery and very smooth. EGT stays below 1200 pulling 6k up Grapevine at 65. Under hard accel smoke is way below the standard for the snap test, not required in CAL yet, but CHP can do if they get the urge at any time. Stock would barely get 16# boost, now hits that easily and maxs around 30.



I would do the upgrade again, might seem pricey but the whole package works together.

 

[KMatson]

My tires are not oversized and I haven't starting the BOMB'ing (gauges are on their way... )



17. 5 MPG highway averaging 70MPH (I know I'm a granny!- shoot my granny drives faster-n-me!)

19. 9 MPG when the speed limit was 55



most of my mileage is on the highway. We live in the country and drive to the outskirts of Houston.



I wonder what my mileage will be after a few modifications ;->



-Slimbeaux

 

[Cumminsman]

as you can see from my profile my tow truck gets 14-16 city empty, about 17. 5 on the highway running 60mph, 16 @ 75-80mph on the highway and in between 9 and 12 towing a 25' gooseneck that weighs 3200 lbs and load that weighs 9k lbs. on the highway. all of these are with the comp on 3x5. mileage is corrected for the tires.

 

[OTRPU]

Course it's a Furd, so it's rotten apples & oranges. Last couple of months, been out long enough to have to change the oil & filter twice using 5k cycle. I've seen 6. 5 MPG on Diesel #1 climbing hills through Canada to Anchorage, AK. ONCE, MT, level terrain with the wind to my tail I recorded 21 MPG. Called myself a lier, but got the same answer when I recalced. It all depends on the load, the environment and the bozo behind the wheel. My usual best average MT & level locked in cruise at 55 is 17. 5. . . tank after tank after tank. The 4. 10s kill me anything over 2,000 revs. Rams better when deadheading but that engines dead, (and it's not 4. 10s). Will soon be reporting on what the brady new replacement engine is doing. Will practice maintenance like a religion, this engine may be alive long after I'm dead.



Cheers,

Steve J.

 

[2ndgen2500]

i get 22mpg on the higway, overhead comp says 24. 1 but that thing is never right. i get 18-19 in the city...

 

[jstyer]

If I run at 65 on highway, I get about 19-19. 5 mpg w/my tires. When I get into it (which is occasionall ALL THE TIME) it only registers between 13-14 mpg. I had 3. 54's in my '99 and like the 4. 10's better, especially when towing the 35'er. Mileage then is between 10-12 depending upon terrain, but then it's worth it to be going up a mountain in the hammer lane at 70 mph+ passing all those pokey psd's and max's in the right hand lane with the four ways on.

 

[georgej]

15. 5 mpg on my commute to work(9 mi). 19. 9 easy drive to coast(100 mi). 17. 7 high speed run to ca. (500mi). 10-13. 5 towing traler(depends soly on speed). All figured by hand and matchs overhead readout within a half mpg!

 

[DToy]

I average about 16 mpg (adjusted for my 315/75-16 MTR tires). Before I switched to the 4. 10 gears I averaged around 15 mpg. My driving is about 60% highway at 65-70 mph and 40% city. Towing a 6K trailer I get about 11-12mpg. This is with an edge comp, without the pump wire hooked up. Best mileage I ever got was 19. 1 mpg, with the 3. 54 gears and 285/75-16 BFG All terrains.

 

[DGFoster]

I get around 15 16 in town and about 18 highway if I keep it around 60 mph,now if my wife drives it,Id be lucky to get 100 miles out of a tank

 

[damon]

16 empty around town and commuting 20 miles on the highway.



10 towing 13000# 5th wheel

 

[Hollywud]

Thanks for all the replies, guys!!!!!!!!