The tires are part of it, but check your fuel filter. I got some bad fuel at a Flying J down here and lost lots of power and killed my mileage. I changed the filter 3 times before i got it all out. Your truck should handle loads like that NO PROBLEM. Hell i average about 16.5 in my truck and its probably 800 pounds heavier, if not more.

 

Will check the fuel filter first. I guess even though it has only been in there for 4000 miles. Thanks!

How much black smoke? Does the smoke clean up after the turbo spools? When your foot is in it hard does it sound like there is an air leak under the hood? Check all you boost hoses for holes and the clamps for tightness.

Stock: very little black smoke, just a haze. Towing Setting: about the the same, with a little more power. Performance Setting: If I lug it it bellows smoke, but cleans up really fast and is gone when boost comes in. Extreme Setting: Haven't tryed.

The Outlook says I'm running 29-30 psi of boost. EGTs stay well within range, takes it a while to get to 1300 on the Performance setting and the hightest I see on Tow is like 1200, but takes it for ever to get there. I don't hear any leaks, but will double check things. Thanks!!

Have you adjusted your speedo for your tire size? If not, you will skew your mileage numbers regardless of whether it is hand calculated or not.

Tires can/cannot make differences. My 2006 got the same fuel mileage with either the stock 265's or the 315's, nothing changed when I added the 315's and adjusted the speedo for the tires.

Before adding the twins, I got 14-15mpg towing 10-12K, something is def wrong with your truck, fueling, or your programmer settings are causing the poor mpg's. I got close to 20mpg running empty. Since adding the twins, I do better by 1-1.5mpg across the board.

CD

Yes, I calculate the different tire size when I calculate the MPGs. They are about 10% off from a stock tire. The Triple Dog does not recal speedo for tire size.

The truck has ran like this sense I bought it back in January. It also is very hard to start sometimes. Is my lift pump maybe on the way out? What should be my rail press. be @cruising and @WOT?

Thanks for the input everyone!!

 

yeah im not sure...just doesn't sound like a cummins...i hav 355/65-18's and i still hav plenty of power. i think i might b fuel related as well....

 

How much black smoke? Does the smoke clean up after the turbo spools? When your foot is in it hard does it sound like there is an air leak under the hood? Check all you boost hoses for holes and the clamps for tightness.

 

Get rid of that K&N as fast as possible.

 

IDK I'm pretty disappointed in mine so far. All stock 16.7 MPG. I haven't pulled anything yet

 

Mine is about 16mpg with 37s on it empty. Was impressed how well it pulled my 12valve on a trailer (about 10klbs) with 37s. Exahaust, afe intake, afe bladerunner, edge was only on 2 (40hp). Stock trans for now also.

 

i just filled my new to me 03 QCLB auto and i got 19.2 hand calculated. Sometihng must be wrong with yours

 

Ancient history.

 

I'm running 16.9mpg hwy loaded w/firewood or 4wheeler. There's definitely something not right on your truck.

 

Does the triple dog adjust for different size tires?

 

i can pull a trailer full of drill steels, up hill no prob, smarty on 3, u must not be getting enough fuel

 

Have you adjusted your speedo for your tire size? If not, you will skew your mileage numbers regardless of whether it is hand calculated or not.

Tires can/cannot make differences. My 2006 got the same fuel mileage with either the stock 265's or the 315's, nothing changed when I added the 315's and adjusted the speedo for the tires.

Before adding the twins, I got 14-15mpg towing 10-12K, something is def wrong with your truck, fueling, or your programmer settings are causing the poor mpg's. I got close to 20mpg running empty. Since adding the twins, I do better by 1-1.5mpg across the board.



CD

 

Does your fuel pressure fluctuate? That can be a sign of lift pump issues. If you fuel pressure fluctuates, your rail pressure might be fluctuating too. My fuel pressure is a solid 10 with my stock lp. My rail pressure sits right at 18-19K pretty steady, it will rise/fall with accel/decel, but when on cruise at 65mph it is a steady 18-19K. Every truck can be a little different, it more about what's steady on your truck that matters. I have a friend with an identical 2006 truck like mine, same make of aftermarket gauges, his truck runs a solid 8lbs of fp and his rp is 17.5K steady at 65mph. He has a little more black smoke than I do at heavy accel. So, differences can be noted but it what your truck is steady at that counts, it is your baseline for your comparisons. I had a long crank problem and a little white smoke problem when my truck had about 30K on it, the dealer did a total flash/completely update and those problems went away never to return.


CD

 

I guess I need to check my fuel press.

 

sometimes a hard start could b a sign of a weak battery...JMHO...they should b changed out every 3yrs anyway

 

Do my boost numbers look about right 29-30 PSI? I thought it would be more around 35 or so. This reading is with the Outlook monitor.

 

Now i know the Attitude monitor with my Edge isnt the most accurate, but accelerating hard it peaks at about 42. Towin it goes to the mid 30 almost every time if im having to get on it hard

 

Doesn't the EDGE boost fool though or are these stock numbers?

 

I think for me it's the gears. I think bigger tires will help my mileage.

 

Are you running stock height tires now?

 

I am, 265/70s

2K at 60 about 2300 at 70. No me gusta

 

I'm running 64 @ 2000 RPMs with my 315s

 

That's the corrected number through my Outlook.

 

35" mud tires 3" lift. Empty 18.5 19 mpg. Trailer 2,500 lbs 16.5, can't even fell the trailer is there. Plenty of power. 3.73 gears. No chip or programmer.

 

Changed fuel filter today. Filter was way more nasty than I expected to only have 4000 miles on it. I may need to start buying my fuel from another spot. Truck seems to have responded to the filter change. Seems to have a little more power on the roll, and better throttle response.

So I wonder what my next step should be as far as cleaning up my fuel system. I normally run Lucas Fuel additive at least every other fill up. Try to do it every time. Is there something better to run in our trucks for this?

 

Hey Guys,
I have a 2006 (Build date June of 06') Cummins 4x4 2500 with 33,xxx miles on it. The truck has 315/70 tires, G56 trans, 3:73 gear, straight exhaust, modified factory airbox with K&N filter, Wilson Thrasher Intake, With a Bully Dog Triple Dog tuner. The truck just does not run or tow like I think it should. With the truck empty, the best I can get MPG is like 16.3 before I even had the Bully Dog on it. I can hook my little 4-wheeler trailer with my wheeler on it (about 2500lbs at most) and my fuel drops down to like 12-13 MPG. This is calculated by hand not using the lieometer. I know my right foot has a lot to do with my MPGs but, I've done this numerous times and come up with the same results.

When I hook even this little trailer to it, I have a hard time trying to pass people on the hghway. Are my tires killing my truck this bad or is this a common result with these trucks? I keep the fuel filter changed on time. Is there anything else that i need to look at? I'm just really disappointed in my Cummins in the power department My buddies Duramax will run all over me!!

Also, just for info. I put a quadzilla boost fooler on the truck, and the truck will not hardly take off from a dead stop in tow mode. It does a little better in performance mode, but is still real lazy until about 1700-1800 RPMs so I took that off.

Any input would be greatly appreciated!

-Coleman

Fuel issues I'd check fuel filter first, then go from there. Iv learned over the yrs (9yrs) as a HEAVY equipment operator, that a bad lift pump will make any diesel run like ****, and progressively worsens to where u can't get fuel to your injection pump