deezulsmoke

I have got six thousand miles on my truck now and took it on a short trip yesterday. On the interstate I averaged 12.5-13 MPG running unloaded around 65-70 MPH. Has anyone else been getting mileage this bad ???? I am about ready to get rid of the truck and get an 03 or something. My 03' got anywhere from 20-22 MPH on the interstate. Truck is an 04.5 3500 dually 4x4 quadcab. One more question also, I noticed my filter minder gets pulled down all the way and this is with stock air box and filter, has anyone else had this happen ???


thanks, Matt

blown32

Could be you have a restriction in the air inlet. I can make full throtle runs and the filter minder never moves! You should be dooing better than 12.5 to 13. Some say MPG improves with towing and or higher miles but with some towing and 8500 miles so far no change from new. I get around 16 - 16.5 interstate @ 75 - 78 MPH and a bit better around town. I tried running slower to see if MPG would improve but just could not stand it! Considering everyone says that I should have lost 1 to 1.5 MPG with the 315s (I would not know as I put them on when I returned from the dealer) 16 to 16.5 is not bad for something that makes 600 pound feet of torque. Would like to get better but.... past gasser trucks with the same size tire would be lucky to get 10 - 11 mpg.

kober

I was getting 12.8MPG empty. Just had the reflash done and I'm up to 14.5 MPG and getting better every tank full...

Lary Ellis (Top)

Don't forget the winter blended fuel will rob you of mileage as well.

MedicShawn

How many miles on your new truck? Is your rear end ratio the same on the two trucks? Anything else different between old and new trucks?

Mine started out life around 13 and with 20K it's averaging 17.25 on winter fuel.

snookinaround

04.5 2500 4by4 4.10 gear only getting 12.8 at 70mph. what is the reflash,what does it do.

kober

The reflash is supposed to fix a number of things like white smoke on startup, console readout accuracy, about a 1.5MPG improvement etc. In my case it was done to fix the check engine light due to low fuel pressure error. When I saw that there was an option now I also had the tech turn on my daytime running lights.
Kurt

deezulsmoke

The 04.5' I have now has 3.73 gears in it, the same as the 03 I had.

murray

Deez,

Yesterday in my new '05 I was running on the highway, and according to the overhead, I was getting 10.8 to 12 mpg. My '04 highway runs were yielding 22 mpg. I looked up at the overhead, and sure enough, I was in the METRIC MODE. Changed it to mpg, and it went up to 20.5. I'm sure you didn't do this.

Alan

Hounddog

What gear.Whats the spec's on the truck.When mine was at that mileage thats kinda what it got running 70 mph and no more.

GMScott

Mine got about 12 -13 mpg up to about 12k. Got the flash and did some HEAVY towing. From what I understand, towing weight is what starts the increased mileage process.
I took 10k lb. payload on a 3k lb. trailer to FL and averaged 7 mpg!! Stopped in S.C. to change the fuel filter, but that didn't really help.
What seems to have helped is pulling loads. Now I'm getting about 16.5 empty and the last load I pulled was a 10k lb. trailer from Pittsburgh, PA to Phila. PA and I got about 13.5 mpg.
Get some weight behind that beast!!

redneckonthenet

Mine is the same set-up. Thats the milage I was gettin with 6000 miles at 70mph. It has came up to bout 18-19 at 20000.

Miles PH

My 04.5 is getting 19-21 on HWY 16-17cty. Now it has 25K on the clock and allot of was pulling a 18'Toy hauler across country Yellowstone/Grandteetons/Sturgus full of toys. It dos get better with moor miles on her clock It dos Now my truck loves keeping around 18-19.5 RPM 70 MPH thats the optimum MPG

Nolynn3

My truck started out getting around 11.5~12.0 but went up to around 14.0 after about 10K miles. I was towing a car trailer at least weekly grossing around 8500lbs, and one heavy haul about 14K up and over the mountains. It never improved any after that, and my son bragged about his 18.5 just about every day. Needless to say, I wasn't all that happy, but I loved the truck. Then a couple of weeks ago I took it in for a horn pad short and got a new fuel filter, the reflash, and they rebuilt my rear differential. They said there was no preload on the pinion. Anyways, I've taken two long trips since then, the first got me 18.2 and today running from Seattle over the mountains to Lake Chelan and back...... 20.2 hand calculated. Now the speeds were low, anywhere from 55~65 but mostly around 60..... But never the less, I'm one happy and very surprised owner.

321 miles round trip......15.866 gallons @ $2.149/gal

Big smile here.

Now I wish I could kill the vibration at 68 mph !!!!

cschulz

At 6000 miles, your trucks still not broke in yet. If you haven't had TSB 18-037-007 done yet, DO IT! As far as your filter minder goes, there have been a number of posts here and on TDR regarding weak filter minders and likely you have one of them and I wouldn't be concerned. The guys with chronic bad fuel mileage problems on the new 3rd gens have almost always been traced to one or more bad fuel injectors (on trucks with less than 5000 miles!) and I would insist my dealer test them if all else fails. Even though your dually is a lot heavier than my SRB you should still get around 16MPG empty avg. in my guesstimation from what I've read on other posts. With a light foot and keeping at 65 and under, I have no problem seeing 20 plus MPG hand calculated. Believe it or not, the guy I commute to work with has a 04 315/555 auto/3.73 qc 4x4 SRB and when he put a Bullydog Downloader in on the Performance setting, picked 2 MPG. You might wanna try one.