why is my mileage horrible?

[scso]

all these threads talking about 18mpg are really bothering me, if i baby my truck im lucky to get 12, usually about 10 or 11 mpg. 05 CC SB auto trans, intake, TB exhaust with cat & muffler. the rest stock, no tuner yet. 78000 miles, i just bought it out of south carolina, i had a 04 psd for a short time 2 years ago and it got 18-19 all the time. theres got to be something wrong with this picture.

[fordfan30]

Check the basics. Tire pressures,fuel and air filters, oil life. My mpg is bad if I dont change the oil on time or if my fuel filters need changed. Are you running a lift with larger tires or driving fast? I got 18-21 mpg last year when fuel was high and before my tires but now that it is back down I get 14-17 cause fuel is "less painful" to buy and I ENJOY driving my truck. I assume you have no other symptoms or complaints about your trucks power.

[POWERED SPARKLESS]

+1 with above, when I had a handfull of injectors bout ready to drop out I was down to 12-14.

[dusted4eva]

I'm gettng 20.6 mpg. with all my mods.

[scso]

i dunno, ive been reading this site for a month now, theres a lot i want to do, im scared this truck was really abused maybe? it was immaculate inside and out, zero rust, engine you could eat off of, not the armor-all engine detail that dealers do, but garage kept-good. no lift, running smoothed over terra grapplers maybe close to 33's? i cant believe that alone would bring the mileage down, i changed oil and trans fluid when i bought it, is the oil supposed to smell like diesel fuel just a little bit? it doesnt seem to be climbing the oil stick, but ill keep a check, maybe bad injectors?

[Baddestt]

What size tires are you running? What is your gear ratio? Have you used synthetic....such as Mobil 1 Turbo Diesel Truck 5w40...it has been known to increase MPG. Make sure that you are changing BOTH fuel filters, clean the EGR valve, and make sure your airfilter is clean...you should do te zoodad mod.

With my mods I'm getting 18.9mpg...highway and 15 in the city

[tabraha]

If it's on larger tires was the speedo recalibrated? I run 34" swampers on my lexus and when I hand calc I have to factor that in b/c I can't recalibrate the speedo easily in it. Also take a look at the threads on how to read the door code for what rear-end you have. Tow oriented rear ends like the 4.10, 4.30 or higher for the big-tire boys drop the mileage a noticeable amount over the 3.73's alot of folks have.

[2005F250]

Stock my 05 got 12. With 35's it gets 11. Towing 8K lbs. it gets 8.

[forddieseldoctor]

what rpm do you run down the highway? how much does the truck idle?

[scso]

i baby the throttle when i drive, trying to keep it under 2k rpms, very little idleing, stock rearend probably 3.73 ill check tomorrow, tires are just under 33 inches tall. it has a k&n intake which ill probably change. i guess ill have to find a dealer who can work on diesels, my local ford dealer knows nothing about them and cannot answer any questions i ask. i appreciate all the help from you guys.