Terrible MPG on 07' Dually W/g56

[ACooper]

Is anyone with a new 07' dually with G56 getting horrible mileage? This is a 5. 9 CTD not the 6. 7L. I have had a 01' 2nd gen and a 05' 3rd gen both with autos and averaged 18 to 20 on highway and 13 to 16 around town :{ I am averaging 11 with my 07' with no go fast boxes. I have already gutted my factory intake and removed silencer along with the muffler and have the exhaust exiting right behind the cab :-laf Still horrible mileage.





Anyone experiencing this problem other than myself?

 

[JensenC]

4wd or 2wd? 3. 73 or 4. 11? Were your first trucks duallys? How many miles on the 07? How do you drive?

 

[NDietel]

get a bigger turbo, bigger air filter, bigger fuel pump, bigger exaust, stack a couple of electronic boxes, do some transmission upgrades and your mileage will go up 100% as long as your not always getting on it. The more you free up your engine, the less work it has to do.

 

[klenger]

Sounds like your truck is broken. Bad injector?

 

[Bodie]

Is anyone with a new 07' dually with G56 getting horrible mileage? This is a 5. 9 CTD not the 6. 7L. I have had a 01' 2nd gen and a 05' 3rd gen both with autos and averaged 18 to 20 on highway and 13 to 16 around town :{ I am averaging 11 with my 07' with no go fast boxes. I have already gutted my factory intake and removed silencer along with the muffler and have the exhaust exiting right behind the cab :-laf Still horrible mileage.





Anyone experiencing this problem other than myself?

Welcome to a NEW truck with a G56 . Your experence IS normal with that truck and driving in town or over 70mph. Let it get broken in and buy some sort of module or programmer with timming and you will be fine. Check out how many RPMs you are running with the G56 @ 70mph, with the auto you were running somwhere around 2000, and with the G56 about 2300-2400..... Thats why



Just give her some time and help.

 

[abrankod]

My 07 is the same setup as yours dually, 4wd and g56, I've got 4200 miles on it and I'm seeing around 11mpg as well, but I think that its definitely not broken in yet as the engine still feels pretty tight compared to other trucks and buses I've driven with more miles on them. Give the engine time and some work to do, and it'll loosen up and you'll see better mileage.



-Dan

 

[JStrasser]

I have an '06 2500 G56 4x4 qcab and just passed 13k miles. While obviously only a SRW and not a dually, I have noticed that highway speed is crucial in determining mpg's.



On a recent 500 mile round trip I kept it closer to 65 than 70 and checked it at the halfway point (hand calc'ed with fuel up to the filler neck) and got about 19. 5. On the way back I kept the CC around 77-78 and the mileage came way down- low teens! BTW, we live in northern NH and there are NO flat roads around us, so "your results may vary".



The low gearing of the G56 must has something to do with this thirst.



Just my input.

John

 

[ilovetrains]

I love the guys that want to know what rear end. There is only one rear end available with the G56.



anyway, your results are in fact normal. There are probably 50-75 posts on this board having to do with overall MPG in 05 and up trucks being lower, and then a subset within that for G56.



The final drive ratio with the G56 is about 10% lower than with the NV5600 or the current gen automatic. That means that the engine is spinning 10% faster in 6th gear.



The overall result is that they will pull heavy loads incredibly well, but the MPG will suffer.



My MPG did not com up until around 50K miles. Heavy towing during break in will also help.

 

[CUMMINZ]

Give about 10k miles and it will get better. :-laf

 

[Regcabguy]

New '07

I've got a whopping 75 miles on mine and can really feel the need for a seventh gear. My popup will be going on shortly and the gearing should work out pretty good. Real smooth transmission and killer brakes. I've got 285-70-16's on it so the gearing is now the equivalent of 3. 97's w/nv5600 someone posted. I read where AAM will be releasing 3. 42's soon. Hope that's reality. Don't really want to go with 35's.

 

[EZeis]

My 07 2500 SALT 4x4 regular cab 6spd 3. 73 gears has 160 miles on it. My overhead started out at 12 MPG when I left dealer and now reads 15. 7 MPG. Won't have real numbers till the tank is empty. Don't know how close the overhead is. That's empty and raul driving. A card hanging on my cig lighter said I wouldn't see good fuel milage till 10k miles. Owners manual said same and will take longer to break engine in with empty or light loaded truck. Once my truck hits 500 miles (not suppose to tow in the first 500 miles), I'll probably pull my 5th wheel to work daily to help break it in faster. :-laf





Earl

 

[RodMorris]

2007 2500

Earl:



Sounds like we have twin trucks. How do you like your regular cab? I love mine. I switched from a '97 Chevy K2500 with the 350 and the NV4500. It has 265,000 miles on it and is probably good for another 265,000. I love this Cummins engine, though. I'll be happy if this Dodge turns out to be half the man the Chevy has been.



Anyway, I don't ever drive over 65, although I'm just as likely to be doing 65 in a 45 zone. I switched to BFG MT 285-70-17 tires at a little under 2000 miles, now have 3200 miles on the truck. I can't say that I've ever had the tank all the way full - I get tired of waiting for the foam to settle - but all tanks have between 17. 5 and 18. 5 mpg. That's commuting to work and back (31 miles one way). I haven't pulled the boat yet to see what towing mileage is.

 

[ACooper]

Sounds like I just need to drive her more and get some miles on it. I drive a company van and my dually sits in the drive just waiting to be driven. I only have about 500 miles on it. About time to put my Arctic Fox camper on it and log some miles with my boat and break it in alittle faster.





My previous CTDs were a 01' SB QC w/3. 54s 4X4 and a 05' SRW QC 3500 4X4 w/ 3. 73s. My 01' had 35's and my 05' had 37's and realize these are much larger than stock but also alot more rollin mass to get moving. Highway was great though RPMs stayed under 2K @ 70MPH and averaged 20 consistently with both. Both also had boxes. 01' had Edge EZ... 05' had a BDDL and kept it on performance and both had strait piped, intake mods and AFE drop in filters.



I am seeing the need for that 7th gear that guys with the G56 are talking about.

This is my first manual and I am loving it! :-laf Once I get more miles on it the fueling box will be added.



I will be doing the 22. 5" big rig conversion on my Dually here soon and will post pics... That will drop my cruising RPMs :--)



Sorry for the long Thread... I am new to posting but have been using TDR since my first Cummins in 01'. couldn't ask for a better resource

 

[EZeis]

Rodmorris,

So far I enjoy my new truck. Only 160 miles on it, so I haven't drove it much. I will take me some time to get use to the trans gearing compared to my old 93 and the clutch on the new truck is for women. I have a hard time with the clutch pedal being so soft. May put a 50 lb spring on it. :-laf



Had a hard time finding a regular cab CTD. But found mine after a long search. Mines Khaki in and out, SLT, sat. radio, upgraded wheels and tires, rear slider window, snow plow prep, tow package, tow mirrors, floor mats, limited slip, fog lamps, and chrome bug shield.



I was going to get a 2500 quad cab long bed CTD until I ran the payload and tow ratings. I'd be over weight all the time, so left me with regular cab or quad cab 3500. 3500 quad cab was 5k more and would eat more fuel from being heavier and I hate buying 4 tires, not to mention 6. :-laf Also 3500 quad cab has a 12200 GVW and would eat me alive on plate renewals. So off I went regular cab shopping.



Earl

 

[EZeis]

Got a little over 1K on the truck now and on a 5 hour trip to ohio, my overhead showed 18. 5 to 18. 6 MPG at 70MPH @ 30 degs temp. Also using cruise. Saw higher MPG while not at highway speeds. Depending on my speed and how hilly or how steep the mountains were, I saw 17. 8 to 18. 9 MPG. Empty truck and just myself.





Earl

 

[MAshley]

For what its worth



06 dully quad 4x4 g56 stock





... . at 30,000 miles overhead now shows 19. 1 city-highway driving with 100 gallons of diesel in the bed at 10K miles i was only getting 13-14 at most,



hauling at 26K lbs I get about 10-11 now and brand new I got 9