I was getting about 12.5 mpg at first. I didn't see an improvement until about 8 or 9K also. It jumped up to about 15-16 mpg in the city. I towed a 12K fiver for about 1000 miles total in that 8 or 9K, too.

My setup is almost like your setup plessm, except I have the longbed. I think changing to a straight-thru muffler and adding the Rokktech did help a little, but towing heavy seems to work best.

Tony

 

Dude. . .just my 2 cents but it sounds like the best mod for you right now is throttle control. I have owned three different CTD and have found they all get between 18/22 MPG if you just play nice. Just did a 2K round trip down to Texas and back last week and even with the 35" BFG's and running 75 or better all the way I still got just under 17.

 

-get your rear diff gears set properly buy a decent gear shop (front optional)
-redline 75W90 NS synthetic gear oil in front & rear diff, (75W140NS if you tow heavy)
-more efficient torque converter w/ matched valve body (shift kit optional)
-redline c+atf in your transfer case and transmission w/ new filter (or valvoline equivalent)
-4 oz howes meaner cleaner in every tank of fuel (guaranteed 4.8% improvement in fuel economy or double your money back)
-synthetic oil and filter every 5000, fuel filter every 10000, air filter every 20000
-adequate tire pressure w/nitrogen
-keep the highway rpm over 2000 but under 2100.
-rokktech or equivalent Timing Sensor mod
-muffler delete or donaldson replacement (cat removal optional)
-oem intake box mod
-intake torque tube mod
-always let your grid heater cycle before starting
-let truck run for 3 minutes before moving, 5 minutes if its cold.
-let truck run for 3 minutes before shutting down, 5 minutes if towing.

opinions?

 

18.45 mpg hand on my 06, ~2000 miles.

DIY cranksensor. all else stock

http://s27.photobucket.com/albums/c154/cranksensor/

 

You need more miles on it for sure. With the auto in town try to get it up to 45 MPH so the TC will lock. Then you can drift back down to around 40 MPH. Any lower and it will unlock. Throttle control is the key. When you get to around 41 MPH cruising don't mash on the go pedal to hard. It will cause the TC to unlock, hence worse mileage.

 

You would be amazed at what towing will do. I had 500 miles on mine yesterday morning. I hooked up a 6500lb trailer and hit the freeways for a day. I pushed it as hard as I could without going over 85mph. I would slow down to 50mph and floor it until I hit 85 or the egts hit 1100, then back off and do it again. I towed about 400 miles yesterday. The truck feels completely different today. It is smoother, and there is a very noticeable power increase. Don't beat it up, but work it hard. It makes a HUGE difference.

 

Redspider where did you hear over 2000 and under 2100. Or is it just your experience. Ive never heard this one be for, just kinda curious. May have to give it a try. Thanks Joel

 

redspider where did you hear aboutI always start up my truck and slowly start driving. How does cycling grid heater? The heater cycles anyway when teh engine is cold & running, not just during stating. What about the 5 minute idle - how does that improve economy (or engine life for that matter)?

 

I wouldn't let it idle for 5 minutes. I let mine warm for a minute then pull away slow and then just keep off it till it warms. I have read about cylender wash and other things. But I think you are wasting more fuel sitting than moving

 

I read it in the OWNERS MANUAL. Yes I realize there is both an initial grid heater sequence and then a cycle, hence the idle time. By "cold" I meant -20 deg C or ~0 deg F, with the block heater plugged in. And if its that cold I'll throw the auto in N while I idle for 5 mins. after that if you still need to idle, thats what the high idle is for.

 

if I idled my truck for five minuts at -20 or lower as it gets here all the time and tried to drive off Id be more affraid of hurting things and straining the truck than letting it warm up for a while,,, I guess Idleing them here is pretty much normal everyone does it here
North Pole Alaska. its been -20f and lower -34f almost everynight here. she idles for atleast 15 minuts in high idle (1500) untill I leave for work. even with synthetics in her the oil in the tranny is too cold and the power steering just growls in the cold till it warms up. so I just let'er warm up I havent ahd any bad results with the oil analysis.

 

If it's cold outside I plug mine in and I drive off when I start it. No idle time. I got 12.2 MPG, bone stock, empty, hand calced on the last tank. I don't need to make that worse. If something breaks because of running it cold so be it, maybe when DC fixes it they might fix the lousy mileage. Stock 05 w/23k
Sorry about the rant, guys

 

man if mine got that kinda mpg Id considder selling mine.lol

 

It just hit me. The best upgrade for fuel milage is a wooden block under the pedal!

 

you guys are getting great milage i am getting 6.8 to 7.4 towing and around
14 running empty this truck sucks 2006 4x2 dually if there is a lemon i think i have it