I'm kind of new to the diesel world. My truck is pretty much stock except for Aem CAI and a 4in Straight pipe turbo back. I average around 14 with mainly highway driving with some city. Just wondering if this is normal for a stock 2500 5.9.

 

Sounds low, but what gearing, trans and tires have you got? Best to fill out your signature so we know what you have.

 

Sorry still figuring out this stuff. Its got a 4 speed with 3.73 gears 33in tires a leveling kit. Turbo holds good pressure, and it doesn't smoke stock. Only thing that might be a little unusual is i have seen egts close to 1300-1500* at wot.

 

New to you truck? My first few tanks averaged about 14 or so. My 2006 is similar except mine is ALL stock. The 06 came with 4" exhaust and a Catalytic Converter.
Getting used to all that torque takes awhile to learn NOT to use it to get better MPGs. The best way to gain MPGs is:

1. Slow down. My 06 goes into torque converter lock up in OD at 50 MPH. Between 50 and 65 I can watch my AVG MPG go up and up. Up to 70 MPH ain't bad - stays steady MPGs, but going past 70 MPH and AVG MPGs start dropping.

2. Drive as though an EGG were between your accelerator foot and the pedal and you are trying not to crush it. It takes a bit of effort to learn to push down EASY, but you can actually accelerate as fast as traffic without pushing the pedal so far - so quick. By doing these 2 things, I improved to 15.5 MPGs and better - best tank yet is 17.13 MPG hand calculated. I use a smartphone app called Fuel Log to keep track.

I think even with the bigger than stock tires you can squeeze 16-16.5 MPGs driving easy as you have some upgrades and no Cat.

 

If you were to recommend an upgrade to help with mpg and possibly egts what would you recommend?

 

Yeah, the 33s are costing you at least 2mpgs. I lost 1 mpg highway on my '03 when my front airdam was removed by a frozen snowbank, and then I added the mopar bugshield and lost another .5-1mpg. 285s cost me another 2mpgs. It all adds up.

 

Going from 32's (265/70) to 33's (285/70) shouldn't cost 2mpg.

I went from 265/70 to 35x12.50 and 6" lift and lost 1-1.5mpg.

My guess is it's either locale or driver caused.

I commute 23 miles each way which takes 1-1.25hrs to work and .75-1hr home, it includes sea-level to pass to sea-level.

When I take the 400' pass commute route I average 16mpg (Before lift 17.5mpg)

When I take the 800' pass commute route I average 15mpg (Before lift 17mpg)

The 800' pass is 2.4 miles long and starts at about 6% grade the last 7/10 mile being 13% and I keep her at 70mph.

 

I suggest, because I really don't know your driving style, that you are suspect to throttle abuse. Reassess how you drive by watching your EGT and keep it below 600F. If you can, you will see 21+ mpg. Secondly, make certain your tire pressure is 55 psi. These trucks are not very aerodynamic. The ideal most economical speed is 50 mph. Speeds above that will kill mpg drastically. Try driving behind a big rig on the freeway. Maintain his speed and stay 2 to three car lengths behind him, watch your egt and see the difference yourself. The trip time difference doing this is surprisingly small.
Steve

 

Are you sure your odometer is correct for actual miles. You may be covering more miles than the truck sees because of larger tires. Try driving down the highway and measure trip odometer to the mile markers, 10 miles distance would even show whats going on. Just a thought.

 

Good call, completely overlooked that.

The post above Foxborough mentioning 21mpg's...You will never see 21mpg over a tank with a 325/610. I've hit 20 twice before my lift and both times were long distance travel on flat road (I-5) sucked up behind a tractor trailer stealing mileage from him with no head or cross winds.

 

I wonder if that why my over head is so bad off. I know most peoples are 2-3 mpg off but mine has been as bad as 8mpg off on a highway trip.

 

IMO, the overhead fuel mileage indicator is not to be relied upon.
Yours is especially off because of your pressure box.

BTW, running a pressure box is a really bad idea. It's very hard on your injectors and fuel system. There are better ways to add power without running additional fuel rail pressure.

 

What would you recommend. I'm thinking about a Bully Dog GT because I have a opportunity to get one pretty cheap.

 

I have a STOCK truck with NO mods that I can tell of, including running the stock size tires - LT265/75R-17 (Michelins at 65 psi) and my overhead display is consistantly off by 7-9 mpgs. I hand calculate each time I get fuel and I topp off the same way each time. My best tank of 17.13 was reading 25.9 on the overhead.

 

There is a reason why so many 2003-2005 Dodge Cummins are using the Smarty programmer. It's far more flexible and powerful, not even counting UDC, than any other programming option out their for 2003-2005 trucks.
I don't recommend any Bully Dog programmers at all.

However, if you are concerned with fuel mileage, just leave your truck stock and drive like a little old lady.
IMO, any upgrades purchased to improve fuel economy will take years to pay off.

Take the 20+MPG US claims with a grain of salt.