My 2004.5 is getting at least 30% less fuel milage than my 2000 truck across the board. I pull a 16' trailer with one motorcycle at times and have only gotten 13.2 miles per gallon at best on cruise at 70 mph on flat terrain with calm winds. (total GVW truck, trailer & motorcycle is 11,000 lbs. ) LOOKING for help or answers?

 

well I'm shocked it's 30% less, but the cummins 600 does get poor mileage compared to the earlier years that have less stock power. In addition, a diesel performance shop says the cummins 600 gets higher egt's. I hear all the time that the gen 2's would get 20-22mpg while the cummins 600 stays in the high teens when unhooked. I have an '04.5 I get 16.5 when around a few stoplights and lucky to get in the 19's when on the freeway. (on board cpu matches the hand calcs quite well)
I then installed the XZT quad box and not only got more power, my hand calcs were 1mpg better but the onboard cpu increased by 2mpg.

regarding the towing...
I tow a 21' toyhauler (8000# loaded) and only get 10-11mpg @ 60mph
70-75mph is around 8.5mpg

 

I also have a 2004.5 which I bought because of some of the millage claims I was hearing about the Cummins. Also very dissapointed. Did find that the motor needs quite a long break-in period, at least 15000 miles. Millage slowly inproves. Also you might want to find the thread about the Power Service (PS) and Marvel Mystrey Oil (MMO) additives. In my case it helped to the tune of empty about 1.5-2 MPG increase. And as above look into the XZT box, I installed mine and around town pulling a small covered work trailer #2500 aprox upped millage to 14-16 from 12-14. Last but not least when going down the highway this engine loves whatever speed you can maintain but anything after 2000 RPM greatlly reduces MPG. On my truck with the 3.73 axle 2000 RPM = about 72 MPH.

Hope this helps....Don

 

Get the Rokktech crankshaft sensor or do the tone wheel mod. Increases the timing by 2 degrees. Should help with the fuel economy. Can read up on mod in this very long thread.
https://www.dieseltruckresource.com/...threadid=71543

MikeyB

 

Its a 7k lb truck, what do you expect? Its not going to get that great of mileage to begin with. Id take it to the dealer, and tell them to do the Fuel mileage TSB flash.. Id bet you see improved numbers.
Scott

 

It has been a known thing that the fuel economy is down on the HPCR trucks compared to the second gen trucks. Not sure why, but that's the story. I wish I could tell you something better

 

I hope the guys that make these boxes are listening until then try the crank sensor it help me about 3 MPG. My truck is stock and it does not seem to work that great with a modified truck from what I have been reading. I would think a box with a economy setting would be a hot seller. Somebody will come up with something cam ,injectors,timing,box ,.........I belive 24 MPG is possible we just need more brains working on it. The weight of this truck is no reason for poor milege , my 91 still got 17 18 pulling 4 ton we just need to figure out what Dodge screwed up and fix it. Someone who can read our ECM's and adjust them would make things better I bet.

 

I picked my truck up in June. Today I only have a little over 1,200 mi. on it. I was affraid in the beginning, my overhead was showing like 13.2 highway. Since that day, it has been going up and up. But the other day I took a 200 mi, trip to Upstate NY, and it was averaging 18.9- 19-1 highway doing about 70 mph. I was happy especially knowing that its still breaking in. I'm hopeing that after a little more mileage on it, it will be showing 20 mpg or more. Im also keeping it pretty much stock other that a high flow air filter, and maybe some sort of smoother intake tube.

 

I believe this is the TSB you want: http://dodgeram.info/tsb/2004/18-037-04.htm I can't be sure as the 05's don't have this problem, as far as I know. FWIW, I'm getting over 18 empty, after 2,700 miles.

 

All 05's have the re-flash for fuel economy.

I too fell like your mileage is too low. You should document the issue with the dealer. The only way DCX will respond to poor FE is if enough people complain.

However, there are lots of reasons your 04.5 gets worse FE than your 2000. I did the same as you, sold my 99 (which got 21 avg. empty with waaayyy more torque available) to buy the 05 in my sig.

New engine vs. old broken in engine.
3.55's in old vs. min of 3.73 in new
Are both trucks the same trans?
Same tires?
Are both 4wd?

I would disagree that the 305hp common rail engine gets worse FE than a 245hp VP44 engine. If you factor in the increase in power out put and the fact that you can't get a 3.54 axle ratio, I bet the Brake Specific Fuel Consumption (fuel used to develop hp for specified amount of time) is actually better in the 305/555 engine.

I do agree that the 610's get worse FE, but its because the 610's are emission's compliant and they don't have EGR.

I have seen the thread on the advanced timing sensor but never saw the results. Sounds like a good idea.

 

Yes, I know that the axle doesn't have anything to do with BSFC.

Sorry. My point is that the 305 engine has the best potential for good fuel economy.

 

I too have been disappointed in the FE results from my '04, but felt most of it was due to gearing, since I was unable to get the 3.54's that Dodge used to offer. I've got 12K on it now with 4K of it from hauling a 12K pound load 4,000 mi to Florida and back. Got about 10.5 running 65-70. Truck had only 3500 on it when I started that run.

Mileage is now up to 17.5 if you keep it around 65, empty. Runs 14 mpg at 70 mph or less hauling 4K boat through the Colorado mountains to Utah.

Had planned on upping the tire diameters a bit when the OE wear out.

I've seen a variety of discussion on fuel economy mods on this board such as the dealer making an adjustment in the ECM as well as air intake mods, exhaust and even power chips indicating that boosting them actually improved fuel mileage.

Anybody have a feel for the best combination of these options?

I don't need any big boost in power unless there is a fuel advantage. This thing runs the 10K foot passes pulling my 4K boat at the speed limit and throttle to spare! (yeehaw!!)

Former Ford big block lover.....and CTD rookie!

 

I would say bigger tires, but not too big. Too big is too heavy and too wide (giving too much rolling resistance).

I would also say look for Quad's timing box. The 2 degree crank sensor is also a good idea, but I like the way Superduty did it better with the tone wheel slotting.

Make sure your tires are aired up. You will sacrifice some ride quality but who cares when diesel is almost 3 buck a gallon. My tire are 5 pound below max in the back and about one pound less than max in the front.

Make sure you change your air filter regularly too. The filterminder does not work, trust me. If it looks dirty when you take it out to actually check it, change it.

 

The filter minders work just fine. A lot of people claim they don't because the don't see what they expect to. The filter minder measures restriction. Your air filter can look very dirty but still not be very restrictive. If you check with all the big name filter manufactures, they all say to use it and don't go by the filters looks. You can have a filter that looks clean and be clogged and one that looks terrible and is ok still.

 

I read my manual, but still have a question, With this filter minder, how does it work?? Do you check it with the motor running, or not??