i got a 2001 f-350sd 4x4 7.3.bought it w/15k on it,it has a k&n air filter on it,i was getting 18-19mpg when i got it,now 8 months later i just get 14mpg,it was a steady decline over 8 months,i keep the oil changed,have changed the fuel filter twice,and run good fuel,i put in fuel additive every other tank full,also ive cleaned the air filter 3 times since i got it ,i now have 32k on it. i wonder if the previous owner had an upgrade chip in it?this is my first diesel,so im learning as i go

 

Perhaps one of the brakes are dragging OR you got used to the performance end of the psd and you are getting carried away a little bit ( hmmmmmmmmmm ). Hope this helps.

 

Jeffgo

I have a 2001 crew 4X4 auto and the best that I have gotten so far with mods (chip set at 65hp and a airfilter and 4"exhaust) is 16.1 and average is about 15.2 or so.
I have seen on here that some guys are geting 18+ mpg but I don't know how?? Good luck... If you find the magic trick please let me know...

Joe

 

Jeffgo,
Your situation is interesting as a friend of mine purchased a 2000 Excursion last year with about 26K miles on it (K&N Filter on board). First 10 months or so he got about 18 MPG and he just now started getting 16. No changes, nothing. I personally only get 15 MPG with mine and always have. I wish I could help.

 

Could be the winter blend of diesel. Don't know much about it but have seen it mentioned often enough when fuel mileage is a topic of discussion. Depends on where you live as to the "winter blend". I just checked my mileage and I'm getting 17.2 mpg. No mods. That was about 20 percent city and 80 percent highway. Normally I'm 40 city/60 highway and usually see 16-16.5 mpg. I've had my truck since Sept. 03. Normally speed on highway is 65-70. Also use Diesel Kleen fuel additive.

 

kmans777 is probably on the right track with his comments about winter blend fuel. Depending on your location, the fuel is probably winterized, which would help reduce the risk of the fuel gelling. By winterizing the fuel, the cetane rating is dropped a little, which requires you to give it more pedal to do the same things as in the summer. I've logged every drop of fuel I've put into my truck, so I can look back and see what affect my mods have done to mpg. February and March are the months with the lowest average mpg, so as the weather warms, I expect the mpg to improve as it has every spring since I bought the truck. I get about 2mpg less in February and March than in the summer.
The colder your climate, the more the fuel must be winterized, and the greater the effect would be.

 

The "fun factor" could be a big issue. I drive only to get "there" and to get good fuel economy. No fun I've manager to keep my mpg's @ 20. Booring, but hey I get excitement in silly things like double digits that begin with the number two.

VW busses pass me but I have time to catch up since I'll go 800 miles between fill ups. When I had a little fun like 70+ mph or rushing to get to the next stoplight i was in the 16-18 mpg range.

I've been using Diesel Kleen fuel additive for a few tanks now. So far I have nothing solid to report. I'll wiat a few more tanks to make a decision about its effectiveness in boosting efficiency.

My tires are often on the hard side. I will carry an ocassional load and don't always release the pressure afterwards.

When my cam position sensor started going bad I had to push the TimeSpaceAdjustmentLever harder (throttle) . I wonder if it could be possible.

 

thanks for all the good ideas/thoughts on this subject.ill give,em a try and see what happens