I just bought a 2005 F-350 crew cad with 3.73 gears and my gas milage is going bad My first tank I averaged about 15 now about 12 mpg highway driving at about 70 miles per hour. WHat is going on my buddies have the same truck getting almost 19 with no mods. And what else can I DO TO IMPROVE MY MPG WITH AFTERMARKET AND ALSO WHAT CAN BE WRONG.

 

anyone???????????????????????????????????????????? ??

 

When was the last time you changed your fuel filters. My truck cruising at 80 got 16.8 last weekend.

 

Sounds pretty low, I got 20 @65mph the other day. Around town it drops to around 14.

 

the truck has 32k on it, and the fuel filters have not been changed yet, also should i be mixing anything in with the diesel?

 

1) The fuel filters should be changed every 15K miles under normal service and every 10K miles under severe service condtions. So you are long past the fuel filter change requirements. This could be one of your problems.
Also the HFCM should be drained every 5K miles.

2) Oil & Filter should be changed every 5K miles. If you are running farther than this between engine oil changes this can effect fuel mileage also.

3) Air filter restriction guage should be checked at least every 5K miles and air filter should be changed when restriction gauge reaches the middle restriction line.

Use only Racor fuel filters that contain the Aqua Block fabric on the primary filter. These can be purchased from Ford or your local International dealer (Cheaper at International ~ $35). Do Not use will fit filters by Wix or any other manufacture.

Use only Racor Oil filters, again either Motorcraft or International, (I have heard that Fram maybe paying to purchase these filters under their name also). Do Not use will fit aftermarket oil filters because they don't meet specs and can cause major engine damage do to improper functioning in the patented filter housing.

The other thing that will effect your mileage is the type of fuel you are using, i don't know what part of the country you live in but the switch to winter diesel fuel has occurred in the colder climates and this will reduce fuel economy also.

As for fuel additives, use either "Diesel Kleen" (Grey or White bottle depending on climate) or "Stanadyne" (Performance formula).
www.powerservice.com/dieselkleen_cetane.asp
www.stanadyne.com/new/ppt/showfile.asp?id=1295

Hope this helps

 

can the fuel filters cause you to have worse mpg,

 

dcf350,

If they are not clean and not supplying the proper amount of fuel to the engine then yes they can.

Please understand that many things can effect fuel mileage. Weather, driving style, load, 4WD vs 2WD, city vs Hwy, type of fuel used (#1, #2 or Bio), tire size, gearing, auto vs manual trans, dirty air filter, to many miles on engine oil.

Have you made any changes to your truck since you bought it? Has it been to the dealer for any work since you bought it? Did the mileage decrease after the weather got cold? Did you switch were you purchase fuel?

Lots of questions i know, but lots of things can effect mileage.

It definitely sounds like you have a problem, but without finding out some more information on exactly what is going on or what has changed it is hard to diagnose over a computer.

Give us some more info. Do you have any other driveabiltity issues? How many total miles on the truck?
Also do not start adding mods until you find the cause of the problem.

Hope this helps

 

thanks for the input i will def. try that right away, what do you recomend as far as a programer and exhaust goes and how much do you think it will improve my mpg

 

dcf350,

Yes i would definitely change the fuel filters if they have 32K miles on them. This may not solve your problem however.

Give us some more information, ie answer the questions that i asked and i am sure we can direct a better response to your problem.

As far as tuners and exhaust go, you may or may not see an improvement in mileage. Alot will depend on driving style. Also if there is an underlying problem with the motor currently a tuner is not going to solve the problem.

First mod should always be gauges, then exhaust and tuner. Adding a tuner without gauges is asking for big trouble.
The favorite tuner on the boards is the SCT with custom tunes for your application.

As far as exhaust goes there are alot of good manufactures of exhuast systems with MBRP being very popular. Cat back exhaust will give you about 75-80% if the benefits of a Turbo back system. The main benefit of the exhaust system is lower EGT especially when towing.

Please not that adding a Tuner or Exhaust (especially turbo back) can cause Ford and/or Dealer to deny warranty work on your engine. BTW these motors come with a 100K mile warranty.

Hope this helps

 

I Just Bought The Truck, I Have Only Ran Three Tanks Through It My First Tank I Averaged 15, That Was City And Highway. Second Tank Was All Highway, And Only Got 11.5, I Had A Small Trailer On Back One Place Atv Trailer, Third Tank 14 All Highway With The Same Trailer, It Has Not Been At The Dealer Yet. The Gear Ratio Is A 373.the Previous Owner Claims He Would Get 16-17 In The City And 19-20 On Highway. I Dont Know If This Has Anything To Do With It But The First Year He Owned The Truck He Put 25k On It And The Second Year He Only Put 5k On It So It Sat A Lot Last Year

 

Im Not Sure If The Mpg Got Worse From The Cold Cuz I Just Bought It Two Weeks Ago. It Seems To Run Perfect But This Is My First Diesel

 

dcf350,

Mixed city/highway driving you will see about 13-16 Mpg depending on conditions. Flat highway empty 16-18 Mpg. Towing anything, or hilly or winding roads will lower fuel mileage. Also in IL the weather is cold now and winter diesel fuel is what is being offered at your local fuel stop, winter fuel will lower your fuel mileage.

You have only run three tanks thru your truck which is not enough for you to determine what kind of fuel mileage you are really getting.

From your posts it appears as though the truck has 32K total miles on it and you have put about 2K of those miles on it in the last 2 weeks or so.

Truck should be serviced at the intervals i posted above. If you have the service records from the previous owner see what they say.
If you have no service records then i would change oil & filter, fuel filters, and check the restriction gauge on the air filter.

Also at 30K i would be changing the transmission fluid and external filter. (BTW the Torque Shift transmission takes special "Mercon SP" fluid that you can only purchase through Ford) do not using any other fluid as it will ruin the transmission.

Also change the differential fluid and the transfer case fluid.

If the previous owner had let the truck basically sit for the last 12-months with very little use, then yes it can cause problems with the truck. Most notably the turbo vanes can corrode and stick. This will cause performance and fuel mileage problems.

Hope this helps