My 98 is a V8

[crazymoon]

ok am i crazy or what. after doing countless maintenance, parts changing on everything that is possible accessible. my MPG is 12(town only). the vehicle is rated at 17/24MPG(3.8 V6). my van did not start this morning it had 243 miles on it after my last fill up and there was no gas. i have read where the vehicle needed a software update to modiufy the fuel ratio(is that true) if not what should i be looking for. this is killing me $$$$$ and driving me crazy. the gas was not stolen either

[12Ounce]

Perhaps a V12?

You didn't mention a OBII code, so there must be none.

I wonder if you have some exhaust restriction of some kind? If so, this would probably escape detection by the OBII and would give terrible gas mileage.

Do the wheels roll freely of any brake drag?

??

[crazymoon]

Thanks for the reply 12ounce, no there were no OBDII codes. the van wheels do roll freely i guess, never tried to see if they had issues, i guess i would put it up on a stand and see if they roll freely??????? What will i be looking for. as many times that i have gotten under neath the van i dont ever remember seeing an exhaust leak of any type, if i had i would have repaired it. Have you heard of the software upgrade to the PCM. i dont remember where i read it but i had somethinbg to do with a tsb fix and then getting the software upgrade. i have been searching the forums and net and i guess im using the wrong words because nothing comes up. filled her up today 19.5 gallons, will see if i get the same results

[12Ounce]

The front wheels should be easy to roll while tranny is in N. Of couse, the drive shaft and some tranny entrails are being dragged along so don't expect a "freewheel". The rear wheels, on the other hand, should roll quite freely...with a minimum of brake shoe contact.

An exhaust leak would not be much of a problem for mileage. A restriction would be... and is also harder to detect.

I heard of PCM reprograms for the '99 and later... not so sure about the '98. A Ford service center should be able to tell you if your's is at latest spec. If it has already been reprogrammed, there should be a little label under hood documenting the action. My underhood has a couple. Approx 1 1/2" square.

[wiswind]

I think 12Ounce is thinking of a possble dragging brake. On the front...Brakes "float" on rods..(there is 1 piston that presses a pad against the disk...and the other one comes to the disk as the caliper pulls it in ..and sometimes they loose their lubrication.....so that one side can stay against the rotor (disk)....I don't think I used the best words to say it......but hopefully I am making sense....

The rear brakes can drag....from the parking brake not fully releasing, even if released inside the car...(lubrcation). If rear disk brakes....they can drag just as described for the front. If rear drum....they can drag from improperly functioning "self adjusters".

Anyhow. If they are not dragging.....then don't worry....but if they are.....a few suggestions on why.

Fuel economy in the winter is often down from the summer. One reason is the cold weather.....
Another is the winter driving conditions. And yet another....is the "winter formulation" of the gasoline.
This formulation DOES vary from one part of the country to the other. The Oxygenated formulations that are Federally mandated for different parts of the country WILL yeild less energy.....and less MPG than the non-oxygenated formulations.

The other thing that I have found.....the pump may shut off.....before the tank is full......even with a little "topping off" which...none of us do......
Also, the gas gauge can be a little inaccurate.....

[12Ounce]

Crazymoon
Did your maintenance actions include checking the "timing" of the cam sensor synchronizer? This area could affect gas mileage without a OBDII code, I believe.

[crazymoon]

the camshaft positioner was aligned properly with the alignment tool and the #1 cylinder at TDC. i will check the back tires as suggested by you guys tomorrow and see how it goes. im really at a loss for this one. the only thing i can say about the fuel gauge is that when the needle is at E and i fill up it will only takes 15-16 gallons, and as we all know we have 20 gallon tanks.