new to diesel and getting poor mileage
 

Hello to all you diesel guys out there. I'm new to the diesel world and need some advice. Last June 09, I bought a 04 Dodge 2500, 4x4 quad cab, 8 foot bed, auto trans, 04.5, 5.9 Cummins. The truck had 4100 miles on it and now has 20000. My question is about poor mileage. At 10000 miles I purchased a TS MP-8. I was getting 16 mpg empty prior to the MP-8, now I get about 14 mpg empty. If I put a load on the truck I get about 9 or 10. I pulled an enclosed 7x14x6.5 trailer to Canada loaded with goose decoys and a Honda foreman 450 four wheeler. I could only get 9 mpg with or with out the MP-8. Talked with a guy at a stop light pulling a very large 5th wheel with a little newer dodge he was getting around 16 mpg. When I returned home I sent the MP-8 back to have it looked at and TS stated they re-programed the unit. It did not help. I have 3.73 gears in the truck and a light foot. Does anyone have any idea what could be wrong or is this normal for this truck. Thanks for your input.

While your numbers seem a bit low I would say the guy at that stoplight was lying to you. I had an 07 and the best it ever got was 10 mpg pulling my trailer empty. My early 04 305 engine gets a best of around 13-14 mpg pulling. Of course the heavier the trailer gets the lower the mileage goes.
If yours is a 325 engine then your numbers may be pretty close to what they should be. Do you have any other mods besides the MP8?

Mileage Help
 

Does your '04 have only 20,000 miles? It's probably not broken in yet. My '05 gets 17-18 around town and up to 24 empty on the road, but it was 3-5 mpg less when I first got it new. The worst I ever got was 11 pulling a 6K lb travel trailer at 80mph in west Texas in 105F weather, full a/c and four people.

Make sure your tires are aired-up. I run 65 psi. Synthetic lubes and oil will help.


Fill out your sig. for future reference.

I can get 24 empty if I take it real easy and drive very soft. In town I only get 17 most tanks but I have a heavy foot during work weeks. Towing with my foot in it heavy I only get 13-14.

Yours sounds thirsty but maybe you have a heavy foot?

I only have the MP-8 mod, I drive with a very light foot, thanks for the input. I read about many upgrades for gas mileage. but don't want waste money.if it won't help.

New air filter, new fuel filter, air tires up to 55-60 all the way around. Everyone of these can gain 1 mpg each if the filters are bad and the tires are low(35-40 psi)

Which air filter works good on this truck, my head is spinning with all the options. I just put a new paper air filter and lubrafiner fuel filter in.

I used to think a lot of the Amsoil EaA189 filter but it folded in half in my stock air box and scared the poo out of me. I am just running a stock air filter at the moment. I did notice an increase in mileage and power when i first installed the Amsoil filter a few years ago.

Well I must agree with you on mileage. I have an 06 and if it keeps it up its going to find a new home. I only get 14 -15 tops with light foot empty. fuel filter new, air box mod. tires max pressure. even tried fuel treatments still the same, I guess some of these 3rd generation either suck on mileage or maybe some rely on that lie o meter on the over head console. If you figure yours out please let me know. I have 373 gears as well.

An 06 w/373s huh? Sounds like mine 13-14.8 hand calc'd in the city. Highway unloaded is better 17-19mpg.

I'm going to blame stop and go traffic and not always getting up to operating temp.


When you guys say "'light foot" or "easy driving", what sort of rpm is the truck shifting at when accelerating from a stop? I've been watching mine. Staying under 1500 is really tough. I seem to be consistent at 17-1800 Truck is an auto so I don't have much control. Much depends on the incline/decline of the road and mph.

Welcome to the diesel world. First off let me say I respect everyone here. Im not trying to cause problems. I have debated with a lot of posters here on the DTR about fuel mileage. I call B.S. on any one that claims they are getting over 20 miles to the gallon on a 3rd gen. I know there are several reputable posters who claim this. If you are getting 14-16 then thats good. I have never got above 18.5-19.5 on my 5 speed Stock Output 2003. On my other 2003 auto I was in the 14-16 range when it was stock. I know many, many, many 3rd gen guys(personally - not on here) and none get over 20 mpg. So, what I guess Im saying is - dont be alarmed. You are right on.

I get 15-17 commuting depending on traffic. Highway I average 18-19 @ 70-72mph, I have broke 20mpg a couple times, but conditions were optimum, (Tail wind, No hills, No traffic, 60-65mph).

All of the above is Hand-calc, my O/H reads 19-21 commuting and 23-24 highway without any mods.

P.S. You absolutely have to get a full warm up or your mileage will suck. When my wife drives in the winter (not complete warm up) she gets 14mpg with a reverse commute.

Right on. I saw an informative post around here about operating temps. I think this is most of my heartache.

when my 04 was stock height and with the intake and 4 inch exhaust,, i could break 22-24 on the highway. n keep it around 18-19 in town.. now with the kore and 35's i can still get 19-20 on the highway.. but now my trannys startin to go so,, who knows

Are you hand-calcing or going off the overhead?

What do you run for filters? With that MP8 you need to be very choosy with fuel filters.

I too call BS on anyone claiming regular mpgs over 20 on a 3rd gen, especially a 04.5+.. Maybe a fluke here or there, but thats about it. 24 just isn't going to happen, at least hand-calc.. I can easily get 24 on the OH.