Horrible Fuel Mileage

[BZieg]

I am new to Cummins Turbo Diesels and I have a bone stock 2004. 5 with the 48re with 3. 73 gears, tires are 285/75-17, only 22k miles on it; and I only get an average of 12 miles per gallon hand calculated!! What is the deal? Is this normal? Never even seen a trailer behind her, just babied, always warmed up before driven, I stay 70 mph on the freeway and just creep through town. Any help or suggestions? Thanks, Bobby

 

[RVTRKN]

19/20 MPG with 48K but mine is the NV5600 and that was new as well. When I was breaking the engine in, it would see 24/25 mpg due to taking it easy at 55 and never jumping on it. Did you purchase your truck new or used? Pay to have it tested with a dyno or a qualified tech and equipment before you complain at the dealer, they have a quick answer for that. I just got back from phoenix towing 5ver and avg. 14 mpg, some miles were without the 5ver but out of 1000K miles 750 were towing.

 

[Lonestar]

It sounds to me like the truck has been babied excessively. These trucks are not meant to be babied, they are meant to be worked, and worked hard.



I have heard of several guys not getting decent mileage until they approach the 30k mark, while others get good mileage almost instantly, each truck is different. I would say hook a trailer to her, work her hard for a bit, and you might start to see an improvement. My 06' was terrible until I installed the Smarty, I went from 12-13 in town, to 15-16 in town.



Corey

 

[BZieg]

Thanks, that was i was thinking. I want to install a smarty but I will be too tempted to run it at full power gain that I might hurt my stock transmission and I want to keep the truck extremely reliable, I am paranoid about every little thing. For instance the stupid door sill rubber is torn on both drivers side and passengers side right at the top corner of the door. Hopefully my fuel mileage will increase, but everyone I know who has the same year and everything as mine gets like 19 in town and 22 highway and I only average 12mpg total, just disappointing.

 

[phloop]

My old 04. 5 DRW 4x4 with 4. 10's averaged 12mpg in the 19000 miles before I traded it in on the 06 built the same. So far the 06 has averaged 12. 83 in the 9100 miles I have had it. I guess some of us just have to live with low fuel mileage. And just hooking up to a trailer and doing some towing is not really the answer, I lug around a 30' camp trailer with my truck and I have yet to see anything over 13. 80mpg.



But I do get over 11mpg while doing the towing now.

 

[timroberts]

Maybe odometer is off with taller tires. Has it been recalabrated just a thought.

 

[BZieg]

You know the odometer was not recalibrated, but even still I don't think the 265/70-17 will make that big of a difference, but your probably right, what fuel mileage do you see TimRoberts? Thanks for all the help it is just kinda disappointing to own a diesel that everyone recommends and says gets great fuel mileage and mine does not. If a Smarty might help, what one should I get? Thanks again.

 

[AMassaro]

You can get much better mileage by cruising at 55-60mph. No one wants to hear that, but these trucks eat fuel when you're doing 70mph+... . I can hit 20mpg at 55-60 all day long. I just averaged 16. 6mpg for 500 miles doing 65mph, about 80% highway, 20% city. City driving, stop and go, really kills the mileage big time. These trucks are heavy and have the drag coefficient of a brick. .

Also, I have the same tires no recal and the mileage is off by 3% approximately. So 100 miles on odo is really 103. 487 miles is really around 500.

 

[Regcabguy]

3rd.gen mileage.

You know the odometer was not recalibrated, but even still I don't think the 265/70-17 will make that big of a difference, but your probably right, what fuel mileage do you see TimRoberts? Thanks for all the help it is just kinda disappointing to own a diesel that everyone recommends and says gets great fuel mileage and mine does not. If a Smarty might help, what one should I get? Thanks again.

Yeah,add 3% as mentioned to your mileage and consider a Smarty Jr. They're being offered by Bob Wagner @ $445 until Christmas. Smoke levels,especially on a stock truck are way down,and #3 should yield an improvement in your mileage and not harm your transmission. It'll wake up the truck and make it much more fun to drive. I've averaged 14. 5 on my '07 w/manual transmission and same tires as you. Smarty on sw#1 is in again,so I'm testing the fuel economy now. So far I'm seeing a slight increase. I've only got 5800 miles on mine. I had to calibrate my 285's to 32. 10" in order to align my odometer to my GPS. P. S. I'm carrying a camper constantly.

 

[rscurtis]

A friend had a similar truck to yours (long bed) that got terrible mileage when new, although he does have a big foot. Reflash 18-037-04 and addition of the Rokktech crank sensor made a world of difference.

 

[TradedV-10foraCummins]

Bobby,



You should consider a Smarty. I have the same truck as you except long bed and 4. 10 gears. My last fill-up before the Smarty I got 12. 8 mpg hand calculated, and my first fill-up since adding the Smarty I got 16. 1 mpg, also hand calculated (running the 60hp w/timing setting). That may not be as good as the older trucks, but I thought that was quite an improvement.

 

[Giachino]

I am new to Cummins Turbo Diesels and I have a bone stock 2004. 5 with the 48re with 3. 73 gears, tires are 285/75-17, only 22k miles on it; and I only get an average of 12 miles per gallon hand calculated!! What is the deal? Is this normal? Never even seen a trailer behind her, just babied, always warmed up before driven, I stay 70 mph on the freeway and just creep through town. Any help or suggestions? Thanks, Bobby

1. Find a safe place and put her thru the ringer... . couple of full throttle runs... clean her out good, esp if you've been excessively ideling for warm up

2. Check your air filter and fuel filter

3. Don't warm her up for 10 minutes (assuming your not in -100* weather)... . a lot of ideling will kill the mileage as well... . just drive easily to warm her up

 

[WHazelwood]

My truck is stock except for the wife and grand kid. Just make a 600 round trip from Atlanta to FL and back avg. 22 mpg. Half the trip was on I-75 and return trip was on US-19. I'm not too hard on it especially with my financial advisor in the right seat but still have to stand on it everyonce in a while just to grin.

 

[Lifted Mega]

I just posted under the tread - IS YOUR CTD TROBLE FREE. I don't how to transfer my post over to here. if someone can do it please do. But as you read my post i have worked my truck pulling my trailer to the coast. And making a trip to oklahoma city pulling a car trailer with a 6000lb truck. So my truck has been worked. Bob from smarty let me try a programmer for 2 weeks and on a trip to oregon i actually saw a slight decrease in my mpg by 1/2mpg a gallon. But the progam was a older version that he knew wouldn't cause any problem being i didn't have gauges. So to be fair that wasn't a true test of the smarty So i will be trying bob and marcos new program soon.

 

[BHolm]

My experience, with all of mine, was that they need to be worked. Your engine isn't even broken in yet, that IMO is the biggest reason you get bad milage. My '06 mega started out getting 13. 8 mpg. After a few cross country road trips hauling a big load, by 30k miles on the same empty loop it would get 20 mpg.



I dont think too many see 22 mpg on a "600" trucks like yours. 19-20 though, cruising at 70 or under should be realisitic. My shorter geared G56 truck gets 17. 5-18 running some city, mostly 65 mph two lane.

 

[KDillard]

On a long road trip I can easily get 20-21 mpg hand calculated. Also letting the truck "warm up" without driving it takes up fuel while not being put on the odometer. You may actually be getting better mileage than you think if you didnt waste fuel warming up the engine. Best way to warm a diesel engine is to put it under load.

 

[eastd]

I have basically the same truck and was equally disapointed when first checked my mileage. I was averaging 12. 5 in town and 14. 5 on the highway, not good compared to the twenty plus I was use to get out of my 96ctd.



The good news is, my new truck had not been worked at all. So after I hooked up my big fifth wheel and made four trips in a row, I started to see improvement. Two weeks ago I went on a fishing trip that was 483 miles round trip empty and I averaged 19. That was mostly 60-65mph driving. Last week I did 435 miles in one day with the cruise set at 70 and got 17. 8 hand calculated.



My truck now has 52,000 miles on it and it's getting better.



Give it some time and work it hard and see what happens.



Dale

 

[timroberts]

BZieg my fuel milage is 18-19. 5 empty 65-75 mph. In town 14. 5-15. 5 . Towing my camper 12. 5-13 (8000lbs)65 -70 mph. Have 81,000 miles started improving at about 50,000 . I think some hard towing is good for your truck. I am thinking about a TST. box for better milage and power. Also all hand calculated. I love my truck

 

[BZieg]

Thanks to all you guys posting!! I really appreciate it. I will check my mileage again maybe after towing a buddy's car trailer. Also what tire pressures do you guys run, I only have D-rated tires and I run like 45psi in the front and like 37psi in the back (truck is never loaded). Thanks again, all of you are very helpful.

 

[Giachino]

I have E rated tires and run 50psi front and back unloaded