I bought a 2003, 4x4, 3500, Quad Cab, Laramie back in October and I am not impressed with the fuel economy.
The best I have gotten is 15.5 mpg using math and not the trip computer.
I drive 6 miles one way to work and normally I get around 13 mpg on a tank.
The truck has an AFE cold air intake and other than that it's stock.
A friend of mine gave me a Bully Dog Triple Dog downloader that he had on his '06 and I have been running it on "economy/tow" but I don't see much of a change.
I am asking all of these questions because I ran the first gen that's in my sig like I stole it and never got this bad of mileage.
I would just like to know if this is normal or if there is a problem with this truck that I should be looking for.
It has 190,000 miles on it and runs well drives very nice.

 

I have an early '04 pretty much like your '03. This truck weighs 3,476 kg empty. It is about as aerodynamic as an outhouse on wheels. Your 6 mile trip won't even warm the motor and you're complaining about the mileage? It makes no sense.

This truck is very good on fuel. It is very sensitive to speed. The ideal speed is 45 mph. At that speed you will see 21 mpg. Speeds above that will quickly kill your mileage. 55 mph = 19 mpg, 70 mph = 15 mpg. Do not expect these mileage numbers when the truck is cold. In my experience, when the truck is cold and not fully warmed up, the mileage will be about 15% less. It takes 15 minutes minimum to warm everything.

 

I understand the 6 mile trip thing. It doesn't get better than 15 on 200 mile trips. I also know that winter time in Montana is a bad time to figure out fuel economy. My point is that my old 12v bomber got better mileage either way. I was just wondering if that's normal mileage for this truck. Thanks for the info.

 

Im in the same boat, I went from my 93 12valve 4WD Club Cab to an 04.5 Quadcab 4wd.... my best mileage is driving right at 45-50mph and Ill get around 20-22..
Highway speeds will drop it to an average of 15.6,
80mph means 13.2 mpg average...
oh well, at least its more comfortable..
Ive weighed my truck three times (empty) at teh local quarry and co-op elevator , and its 7984lbs..

 

If I'm careful and keep speeds less than 75'ish, I can get about 18mpg. My only mod is a Smarty Jr, set for towing and economy.

One thing I learned while driving through WY was how sensative the engine is to temperature. At temps below 40'ish, it does much better with the winter cover fully closed.

I have never seen anything anywhere that a cold air intake does anything positive for an essentially stock truck.

Maybe your cold air intake is keeping the intake charge too cold, and it's not running efficiently enough. I would go back to a stock air filter and intake and see what happens.

 

Do you have any codes? Get an Ultraguage and monitor IAT, CT, etc. All the 3/4 ton CTD trucks I've have had the same mpg. I had 2-93s,a 97, 01, &03. My 03 has the most power but still gets similar mpg. What are your cruising boost and egt? Max boost and egt?

 

twice as many valves, and higher fuel pressures are a start

I have an 05, and with the 3rd injection event, I would get that mileage stock, with an auto slush box trans, a smarty on 5 picked it up to about 18-20 mpg at 70 on the truck in my sig. stock I was getting 15-16 highway, and about 10-12 city..

you cannot compare fuel mileage from a CR to any 12 valve at all. I have yet to see a CR get better mileage than a similar structured 12 valve. I think you will find a hens tooth before you see that actually.

anyways at 190K, id be leery of injectors, how are their condition? originals? perhaps that can be hurting you.. any signs of hurt or bad injectors? hard starts? smoke? etc? if they are original injectors 190K is EXCELLENT life for them.. I lost mine at 200K on the dot. from there, id worry about DTC's, but it wouldn't hurt to get them. wear and tear also takes its toll on everything. fuel system and injectors are no exception

50K miles later, the trans went, but that's a whole other issue back on topic, has the head been checked? I know the 03 and 04s have the best mileage of the CR motors, but are known to drop valve seals.

id trade mine for an 03 same configuration, with a six speed in a heartbeat. I've seen several 03-04s with 600-700k miles on them with less maintenance than my 05.

so I congratulate you on getting a good one..

 

You are correct. All single event injection engines will get better mileage than a CR multi-event system and they will also see much longer injector life as well. This is because of the higher fuel pressures causing erosion, but it is mostly due to the multi injector cycles which increase the injector's duty cycle. Some folks on this forum accuse Bosch of making junk injectors, but I suggest the observed reduced injector life of CR motors is simply the cost of reduced emissions and noise, after all it isn't free.

I have an early '04. The '03 and early '04 use a 2 event injector cycle, but when the CAT was introduced in late '04 and later, the injector cycle went from just Pre and Main, but to Pre, Main and Post. (the Post supports the CAT temperature). It is unreasonable to expect the same fuel economy with the older single event systems.