fuel mileage issues

[tooled]

I have read many fuel milage threads on this site but need a few more answers please. I have a 2000 f-350 psd, k&n cold intake, 4'' mbrp turbo back, tower with guages and evolution programmer set to tow mode[60-hp]. The problem is last year I only had the intake and was getting 13-14 mpg towing a 8500 lbs. trailer. This year I made the other mods. and now I only get 9.5-10. Does this sound right? I'm not driving it any different than last year [while towing]. However I did just change my fuel filter for the first time. Any input would be great.
thanks-tooled

[mschn99]

first of all, are calculating milage by hand, or trusting the overhead computer???

are you keeping the air filter good and clean??

Do you regularly check your tire pressures??

lets start with the basics first....

and welcome to the forum!!!!

[tooled]

Mileage is calculated, tire pressure is checked everytime we head out. Just cleaned my intake 400 miles ago. Man this is just killing my checkbook.

[mschn99]

this is kind of a gray area. Terrain type (IE lots of hills) can affect fuel economy in different ways. 14 would be great with a heavier trailer. 8500 isnt huge, but that is a pretty substantial trailer. 10 is not terrible, although i would expect a minimum of 12 generally towing something around that wieght. What kind of economy are you getting unloaded??? and does it seem to be running well........and how many miles were on that old fuel filter????

[tooled]

The old fuel filter had 23000 miles on it. The terrain we travel is the same as we traveled last year. I was dang impressed with the throttle response when first programmed and it actually is getting better fuel mileage when empty. The only two things I can think of is 1-fuel filter and 2-the programmer. Am I mistaken or are the programmers supposed to help with fuel milage as well as power? thanks for your input and help!

[mschn99]

how many miles on the truck?? also, has any thing else changed...tire size...etc. Is it running good all the time, even when its towing, getting the poorer milage?? have you even switched fill up stations??? maybe try a cetane booster next time you go........

[tooled]

Just turned 24000 miles. Use stations that sell alot of diesel except this past fill-up I decided to try bio-diesel and i'm pretty impressed. I think I will tow next time back in stock mode and see what that does. But I think this will give me a good excuse to buy a t6 chip. Since that seems to be a popular choice around here maybe you guys could tell me if you noticed any increase or decrease in fuel mileage while towing with this chip.