From what I am hearing on other sites most people with a 3rd gen are getting 19-20 mpg. So why am I only getting 13.8. The mileage TSB has been done and I am running the edge w/attitude and an AFE air intake. I very rarely go over 60. I know I get on it sometimes but not that often. The guy that owned the truck before me took it back to the dealer complaining about only getting 12-13 mpg so they did the re-flash of the computer. Any ideas on why my mileage is so bad and what I can do to improve it? The truck has 31000 miles on it.

 

Please fill out your signature, so everyone knows what your truck is.

DMH

 

Welcome to DTR

Might be it's still too tight, not broke in. I read that a few guys will actually borrow a trailer to a heavy tow and really give the truck a work out for 1-200miles. My mileage continued to improve til about 80K miles. Worth a try.

 

Done. If there is more you guys would like to know just let me know and Ill try to fill it out.

 

Definetly could need to scrub in some still if you have not hauled heavy with it and got it good and hot a few times. I think there is a couple of tsb's for poor mileage you could look into also with your dealer. My mpg is around 18 average. Getting air in and out always seems help with engine performance.

My 2 cents,

 

Why do similar vehicles with apparently similar drivers get great discrepancies in their fuel economy? It is a mystery that needs further exploration on this forum.

 

I think the biggest factors that effect fuel economy are: amount of stop and go driving, type of terrain, aggresiveness of the driver coming away from a stop. My normal driving is mostly highway on fairly flat terrain with few stops. When I go into hilly areas or areas with lots of stop lights, my mileage drops off considerably.

 

Because everybody has a different way of driving and a different way of calculating the mileage. I gave up on most mileage discussions a long time ago.
It is true that the '04.5 - '06 models get worse mileage. And I don't agree that you must drive it 80,000 miles to get mileage that is going to be significantly better. If you think your mileage is going to go up by 30% or so just by breaking in the engine and it's going to take 80,000 miles to do it, don't hold your breath. The new trucks don't do as well as the earlier trucks, high speed on the highway and fast starts in town are really bad for mileage. Going to 315s from 265s (and correcting the speedo) cost me about 1-1.5 mpg.
If everybody just left the mileage computer alone and it was allowed to average for a few thousand miles, and the speedos were all corrected for tire size, and noone was running a chip, we could have a fair discussion about the results. Then take the same perameters and make a group of trucks that have chips. The second group must hand calculate from an absolutely topped off tank. Then we can have a useful discussion.
To drive down to the store and back, or make a short cruise on the highway of just a few miles, or to partially fill the tank and then enter the mileage discussion is a waste of time. And with increased rail pressure the computer can be fooled into thinkng the mileage is better than it is.

Wetspirit

 

I you don't have gauges on your diesel you can't improve your fuel mileage period. Reason is the computer fuels the motor by the reading it receives from the map sensor (Boost Pressure). Simple equation really, more boost equals more fuel. Can't tell by rpms without a boost and pyro gauge. Fool the computer with a box on map sensor/timing or injector duration reading and she drinks more fuel. You can't totally override the stock ecm. Let's all at least admitt bigger tires and edge boxes don't make for 19-20 mpgs without gauges......come on! To many variables filling the tank, to the neck, time and again. Lets not forget a 3/4 or 1 ton dodge is about aerodynamic as a brick and weighs 7000 plus pounds. If a fellow wants a 3/4 ton truck to get 20 plus mpgs start with gauges and modify you driving to keep boost below 5 psi and pyro around 600 F. Speed and tire size are next and city/idle time kill mpgs

 

I think it is the driving habits. I can drive my truck and get great mileage from it. I have at least a dozen or so full throttle burst during a tank of fuel (accelerating on an on ramp, passing, etc.) and still do 650-700 miles. This morning was 664 on 30.02 gallons. Occasional 70-75mph, mostly 60-70mph. Lots of stop-n-go. That is 20-22 mpg. My wife gets in my truck and and the mileage will drop to 17-18. She does not hot rod it. I suspect she may be keeping it in gear to long before shifting or down shifting more than I do. I tend to coast if I am in eye-shot of a red light or some other reason for stopping. I shift at 1800-2000. Sometimes short shift (2dn, 4th, 6th). I've been told that is not good for the tranny. But just to reiterate, same truck, two drivers, drastically different mileage.

 

What gears is your truck equipped with? Gearing is a major factor. Do some searching in here. This site is packed w/ info.

 

some things that help get crappy milage can be big off road tires or auto trannys or 4.10 vs. 3.73 or 4x4 or fueling boxes that you "feel the power" quite often or 3500 truck vs 2500 or city driving vs highway drive or driving stlye or lots of heavy "stuff" in the truck and more importantly is which engine. My 2500 2WD '03 305/555 HO NV5600 3.73s and truck weight at 6750 lbs will average 22+ mpgs on a 110 mile a day work commute for two years tank after tank for 54000 miles and all highway miles [65 to 75 mph]. I don't have any city to drive in so that is in my favor for better mpgs.
Big tires and autos with city driving will scrub mpgs quick.
JIM