Cummins that gets terrible mileage

I have a 2004.5, 325/600 Cummins engine Ram 2500 4x4 Auto with the 3.73 rear end
I have never done better than 10 in the city and 14 HWY
I love the truck but hate the mileage
Everyone Ive taken it to says theres nothing wrong
I have 30,000 miles and am a vey conservative driver I towed a friends 7,000 lbs Cobalt Boat to the lake and got 8 MPG What do I do? Joel
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"joelb7" wrote:

Is this a automatic or manual and do you have oversized tires on it or not? (trying to get a better picture of your problem)
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"SnoMan" wrote: > [quote:a9293a3132="joelb7"]I have a 2004.5, 325/600 Cummins > engine Ram 2500 4x4 Auto with the 3.73 rear end > > I have never done better than 10 in the city and 14 HWY > > I love the truck but hate the mileage > > Everyone I've taken it to says there's nothing wrong > > I have 30,000 miles and am a vey conservative driver > I towed a friends 7,000 lbs Cobalt Boat to the lake and got 8 > MPG > What do I do? > Joel[/quote:a9293a3132] > > Is this a automatic or manual and do you have oversized tires > on it or not? (trying to get a better picture of your problem)
Its an Automatic and it has the Stock Michelin Tires on it. I also got a Snug Top camper shell trying to make the truck more arrowdynamic Its a 2004.5 Top of the line Leather 4x4 all stock I have a friend with the same truck and he gets about 5 mpg better I really think something is wrong I mean come on 10 MPG city 14 hwy (going 75-80) Joel
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"joelb7" wrote: > It's an Automatic and it has the Stock Michelin Tires on it. > I also got a Snug Top camper shell trying to make the truck > more arrowdynamic > It's a 2004.5 Top of the line Leather 4x4 all stock > I have a friend with the same truck and he gets about 5 mpg > better > I really think something is wrong I mean come on 10 MPG city > 14 hwy (going 75-80) > Joel
diesels have a sweet spot of sorts RPM wise where they do there best but that aside 14 MPG at 75 to 80 is not far off for a big truck like that with a deisel. If you drop to 65 to 70 it will likley increase a few MPG towing and not. A few things you can try, when towing do not lug the motor, keep it above 2000 RPM when pulling hard but under 2500 on long pulls, above or below that speed MPG can suffer when pulling hard. Also make sure you have got your tire pressure up and that helps (my buddy gained 1.5mpg on hiway with his Dmax when he increased tire pressure from 45 to 65 to 70psi on his crew cab 4x4. Also, something else you are fighting on a Dodge is that they did away with the front axle disconnect in 03 so you are ALWAYS dragging the front axle with you (axle shafts, drive shaft and diff) even in 2wd This can cost you 1MPG or more on highway because it consumes several HP as hiway speeds. Dodge really screwed up on this one because they had a whole new axle designed for 03 and left out the abilty to even add lockout hubs which was really dumb. You might try changing your front and rear axle lube with fresh 75w90 (SYN if you want) and that may get you another MPG on hiway. I have seen fresh axle lube perk things up a bit especailly if it has not been done for a while. And in closing, a 3.73 with a automatic is a bit tall to tow in OD at times so MPG may suffer if you pull it hard. I have driven several Cummins truck automatic and manuals and they seem to run best with a stick with a 3.73 and with a automatic with 4.10s because the automatic carries a taller OD ratio than the 6speed does. It is a nice engine for sure, just need to load it properly RPM wise if you want maximum work with minimum fuel consumption.
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joelb7 wrote:

That does not seem right at all. If I were you, I'd check with these guys.
http://www.dieseltruckresource.com/dev/index.php?s
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i have one of the same, only in 3500 http://inlinediesel.com/trucks/3gen/1/index.html (at the bottom).

here in montana our highways are wide open and when i drive it i get about 14 in the city and 17 on the highway. my wife gets even better when she drives it.

theyre either bad wrong, or theyre overlooking the problem. do you idle extensively? is your parking brake on? have you ruled out a fuel leak? how are your math skills? :-)

take it to someone who cares about finding your problem. i doubt youll find anyone like that at your dealership.
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Nathan W. Collier
http://InlineDiesel.com
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There was a TSB issued specifying an ECM re-flash for poor MPG complaints. Read up on this (http://turbodieselregister.com , http://www.dieseltruckresource.com , and possibly http://www.dodgeram.org - I don't know if the newer TSB's have made it to Dave's site yet), then go visit your dealership again. Something is WRONG with your truck - fuel economy should not be that bad. Also, check the oil for fuel dilution (doubtful, because to lose that much MPG due to fuel leakage, your engine would be toast by now, but it's simple to check) - there have been some problems with the '04.5s and leaking injectors.
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wrote:
i have an '03 3500 srw, with the 3.73. i probably average between 15 and 16 mpg, but a lot of that is stop and go back and forth to work. one the highway, if i keep it under 70, i get about 22-23 mpg. at 70, i get about 19. mine is the 305/555, which supposedly gets a little better mileage than the 325/600.

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Mine is also an 04 600 CTD, except it's a 6 speed, 4X4 with 3.73 rear. My very first tank produced 19.6 MPG. My truck gets decent mileage but if I drive it 80 MPH, the mileage goes to heck. At 85 MPH it's right with my 92 W250 w/360 V8, 5 speed and 4.11's. The 04's sweet spot seems to be just under 2,000 RPM. I really regret the non-disconnect front axle and the 3.73 gear. My friend has a 6 speed 02 with 3.55's. Much better on the highway. If Chrysler didn't make it so hard to put old fashioned locking hubs on the front axle, I would do it tomorrow.
One other thing no one mentioned. Do not believe the mileage on the digital read out. Mine always reads lower than the actual mileage.
Al
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Geez, I have a 2500- 325-610, getting about 22 MPG, thats empty..when i hook my 5th wheel RV to it this fall sure will change the fuel mileage. Mutt

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What transmission? 4X4 or 2 wheel drive?
Al
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Its the 48RE tranny 4X4 ThunderRoad package..drove from Lawrenceville, Ga. did not have to fuel til i hit the Texas state line. Also just returned from a trip to Buffalo,N.Y..both trips 22 MPG.. Mutt..

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"Kay & Erv Mutton" wrote:

Lawrenceville,
This is highly suspect especaily the part about it being EXACTLY the same both times and not at any great speed if you did. ALso I can go from Ohio to SC going thru parts of 5 states on one tank of fuel with ease in my old gas burb (560 miles) but that does not mean I got better 20 MPG either.
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Sorry for not giving EXACT numbers, the Texas trip was 22.2 MPG. The Buffalo trip was 21.9 ..And this is not suspect, its the truth. And I frankly my dear I dont give a hoot if you dont believe it.

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