OK i will try and make this story short. About for a year and a half now my truck has dropped it's MPG from 18-19 down to 14-15. I have had a shop look at it and they say it is running great. The injectors all meet the standards, it doesn't really feel like i am lacking power, and there is no other noticable problems. About 2 months ago i add a edge w/ juice in hopes that would help and it did alittle.(i'm now getting like 15-16) One idea that has been brought to my attention after finding this forum is that maybe my speedometer is off. I went from the 245s two 265s and that was probably about a year and a half ago. I just didn't think that small of change in tire size could throw of my speedo that much. If anybody has any ideas or thoughts on this please let me know!:):)
Thanks for any help,
Tim :D

Dragging brakes: follow the steps here in post #7 http://www.dieselplace.com/forum/sho...her+soft+brake

And why it happens, in post #4 here
http://www.dieselplace.com/forum/sho...ghlight=brakes (http://www.dieselplace.com/forum/showthread.php?t=276509&highlight=brakes)

This means the pads should damned-near fall out on all 4 corners.

And the switch to a 265 tire resulted in no change to my trucks.

I read the post you gave me and it seems like those happened pretty early. Mine has about 87,000 on it know and the milage dropped at about 65-70,000. You think it could still be brakes draging. I don't hear anything.

It happens to ALL my trucks. Inspection of any corner with the wheel removed should reveal an inner and outer pad of the same thickness.


It's like driving with the brake(s) applied lightly and is unnoticeable to all but the most Anal technicians (like myself).

The only other thing to check is the restrictor gauge on the air cleaner (it should be retracted). If it isn't, an air cleaner is cheap. BTW, what are you driving??? Also, winter blended fuels typically carry a 1.5-2 mpg deficit around here.

I'm driving a 02 2500 HD. I love the truck, this has been the only propblem i have had with it. I bought it when it had 49,000 miles on it. i have a K&N intake system on it (think i will go back to stock after reading some interesting news), straight piped exhaust, and the edge w/ juice chip.(got that mainly for hope in MPG improvemeant)

If the brakes are dragging well enough to cause mileage reduction, I have little doubt there would be a burning smell. The tire size difference makes more sense.

The tire size change you reported definetley will cause your complaint.

The tire size may make the speedo off 3% or so. Check the old diameter against the new. Also, the bigger the tire, the more the weight. I saw about a 2 MPG reduction when I went to a larger tire, but I have averaged 15.7 over the last couple of years (calculated) with mostly city driving and putting my foot it in often :D. Take out the towing and it would be around 16.5.

Max 23 mpg on highway at 65 before big tires, 21 after.

I am running 265X75 Michelin MXV tires with a corrected speedometer. Today I checked mileage after reading this post. For 332 miles I used 18.01 Gallons of fuel. Figures to be 18.4 MPG. 315 miles were at 74 mph, some slowing for trucks to 60 MPH. 17 miles were stop and go, never over 30 mph. About 100 miles I had a 20mph headwind.

Truck is a 2002, 87K with new injectors running a Hypertech tune at 50 HP, 4" Banks Turbo back, K&N Air.

Hope this helps.

The brakes deal holds water. Even if it's not the ONLY source of your lowered mileage, it's VERY likely to be a partial factor.

Besides, the problem progressively erodes your stopping power. You might be surprised how much better your brakes work afterwards. It's a DIY job too. If the pads are not unevenly worn, they could still be sticking some and just not showing signs yet. Grease em up! it's easy!

I just did this on my camaro and the difference was pretty big. Virtually identical brake design, smaller scale.

The tire size may make the speedo off 3% or so. Check the old diameter against the new. Also, the bigger the tire, the more the weight. I saw about a 2 MPG reduction when I went to a larger tire, but I have averaged 15.7 over the last couple of years (calculated) with mostly city driving and putting my foot it in often :D. Take out the towing and it would be around 16.5.

Max 23 mpg on highway at 65 before big tires, 21 after.

X2 I corrected my speedo with the PPE after I calulated mileage after a tank and it was way off i lost 4 mpg before I corrected the speedo.

Look right behind your inlet intercooler pipe. Mine was rubbing on the the hard line for the fuel filter, and my mileage dropped about 3 miles to the gallon.

i would check the charge pipe but i have only run one tank through my truck with 65's on it and have noticed a 3 to 4 MPG difference. i would say that is all your problem is. especially if it is still running well.

alright, so i am getting the superchip tirepaq (should be here in a couple days), checking the brakes tomorrow and will look at the intercooler pipe and charge pipe. Thanks for all the suggestions! Hopefully i will find one of them that helps.