TX_Diesel

Ok,

I bought an 06 Quad Cab 4x4 Cummins, SWB, 3.73 gears April 1st. The truck is still completely stock and has 4300+ miles on it now. My overhead computer reads about 3-4 mpg higher than I'm actually seeing which is 13-14mpg. The computer reads 17-18mpg.

So i called the Dealer asked about a reflash for the computer or if there were any fixes. The service writer asked if i had been towing anything and I said no the only thing i've towed was about 6-7K lbs for little over 600 miles running around 70-80 mph the whole time.

The service writer told me I need to hook up to a heavy load 15k lbs and run the truck hard, to properly seat the rings and sometime around the 10k mile mark i would begin to see better mpg and even more power.

My question is, does this sound right to anyone? Has this been anyone's experience? I've never had the dealer tell me to hook up to a heavy load and run my truck hard.

Thanks in advance for ya'lls input.

8mpg

give it a good 10k miles for breakin, you dont need to tow a heavy load like that. Dont granny it though, these trucks are meant to be driven. Im getting the same milage and it has come up about 1mpg since I bought it but still waiting for a flash.

Mcmopar

20-30K sounds more like what people are reporting these days, Oh-stay away from GAS your diesel won't like it.

blord

I've had my new dually for a week now. The 1st tank (236 mi) with mixed driving was 14.9 MPG (overhead was 2.5 higher).

2nd tank was a highway triangle 80 mi, 85mi, and 65 miles. I drove the triangle at 65 on 1st leg, 70 on 2nd, and 75 on the 3rd. I got 18.18 MPH (OH said 19.8).

At the end of the highway run I had 523 miles on the clock. I would say that 13 MPG is a might low considering mine isn't broken in either!

I think there are two flashes that are supposed to help one for CEL and one for either hard start or white smoke. supposedly make a tremendous difference on some vehicles. The best that I recall the TSB # is something like 18-003-06.

Dodgezilla

Towing a heavy load and pushing the truck hard WILL help. The first time I pulled my trailer loaded to about 10,000gvw I noticed that the truck felt stronger and the mileage DID start to go up. Around 10,000 miles and it went up some more... I started out at 13mpg city when new. Now I get 16 city with all the mods. If I turn the boxes off I get 17-18 city but that's with injectors and turbo......

CAR Hauler

My 04.5 gets 10 around town, I seen as high as 16.4 empty on the highway. It dont matter what I do It su*ks. I give up, every truck i have is bad on fuel.
I think it is cause i start it drive 6 miles and shut it off I live to close to work.

SSminnow

Without a doubt that is why your truck gets horrible fuel economy. Your diesel has not even come CLOSE to warming up at only 6 miles!!!!

Brad02ctd

I started towing heavy when the truck had 700 miles on it(case 580 back hoe on top of a 25' 10 ton trailer), and i pretty much tow 7 days a week(heavy). The truck has 7100 miles on it and seems like it is gaining power every day. I didnt go to a scale the other day but just doing the math i grossed around 30-31K lbs and that truck barely knew the load was back there. As far as fuel economy i ran down to virginia last week and drove 65 the whole way and i got 16.8 mpg when towing it all depends on the driveri think, i can burry it down to 9 mpg driving like a moron or i can granny it and get in the 13's when towing. just be patient(how ever you spell that) with the truck it will wake up.

SSminnow

You get 16.8MPG grossing out @ 30K LBS

Blast Chamber

Are you asking why the computer is reading different than your hand calcuations, or why your truck is getting low mileage? A 3-4 mpg difference is pretty large considering your truck is still stock. I'd question whether you are getting consistant hand calcs, as it's hard to fill the tank in a consistant manner without the vent kit mod.

That being said, your dealer is right about heavy towing helping to speed up the break-in period, but you will still need to be patient. You've had the truck less than 2 months and it has only 4,300 miles, so it has quite a ways to go before the engine and truck in general are done with break-in.

xyzer

IMHO.....Thats not why you are getting 13 MPG! This is my 3rd new break in and yes they do improve with milage but not 7 MPG! My first 2 diesels new got 18-19 new and improved 1-2 mpg with more miles. The present one got 13 new, the overhead was off...then I got a CEL and for battery tempeture somthing or other. They reflashed it and I just pulled a 20.2 MPG and the overhead is close...well either it got broke in overnight or there were some bad numbers in it brain. I wouldn't own one of these trucks if it got 13mpg all the time! Personaly I don't buy the break in excuse!

SSminnow

Well, if it was a small truck that got 13MPG, I would not be happy either. BUt, we ARE talking about a 4 TON truck here!!!! I am not saying 13 MPG is good for our trucks, as plenty, if not most get better then that, inlcuding mine. BUT, it does depend on driver. How you get over 20 MPG is beyond me. As for the 10K I have owned my truck (it has 106K on it now) I have tried on a fwe tanks to get the ablsoute best mileage possible, from throwing it into neutral and coasting to a stop at a red light, no RPMS over 1300 when shifting, and no speeds over 65 MPH, and the BEST my truck got, drving like an old woman was a tick over 19 MPG. Driving normal, 70+MPH, 1600-2000 RPM shifts, I will get @ 16 MPG @ town and @17-18 depending on how much highway driving I do. If all highway, closer to 18, and if more in town, but some highway, closer to 17. If you are getting over 20MPG, I can imagine how you are driving your rig. I think the fuel economy on our trucks is over rated anyway. I mean, did we really buy thse trucks for the fuel economy Sure it makes for a great conversation piece when you are bench racing. And yeah it's great that a truck of this size gets better fuel economy then my wifes Jeep GC. BUT, if fuel economy is what I was after, I would have stuck with my gasser trucks.

Brad02ctd

no no sorry that was empty down there and back i wish it was that good towing.

xyzer

We all buy them for different reasons....I drive a diesel because it does get good milage empty! They always have. Then pull there hearts out when you need them. If I got 13mpg all the time I would own a stinkin gasser! Lots of people out there get 18-21 MPG with these 4 ton rigs....I do and it didn't happen until it was flashed not after 10,000 miles!......and that was my point. If you have accepted your MPG....fine. But I didn't and it went from 13.8 to 20 MPG so go figure. Thats what I am telling the OP in my opinion 13.8 aint right and neither is wait 10,000 miles!

Tree DR

Brad, I'm with you on the fuel mileage. Mines only and 04 but my other 5 were all in the 15 towing, 18 hwy, just like this one. Now those are averages. Thing about people I've found is they only tell you the exceptional MPG trips they got not the average.
Driveing habits are a hudge factor in mileage. Sitting at the stop light holding your truck in place with the clutch or throttle. Some people can gain 2-5mpg just by driveing different. It seems odd to me that a few people get 13 in town with a 4x4 1ton, and a lot get 20 or more in a lifted 35" tire rig at 70+mph. People can say what ever they want to on here and is it true?
I don't doubt that there are some messed up trucks that get 13mpg. As far as break in? I broke all my trucks in pulling 26k or more as soon as I got a ball in the bed. I can't say it made any difference.