So Ive had my new 04 Ex for a little over two weeks or so now and Im more than shocked. Im not getting the same kind of fuel economy that my 05 PSD was getting....

The specs,

2004 PSD 6.0L,
108,000 Miles.

Bone stock.

Valve covers still are oem International the do not say Rebuilt on orange International stickers. They are Blue and says 2004 Motor.

Now im driving always highway miles and average 100-180 miles per day min somedays more.

Now I did swap the stock tires for 315 but I have lost over 300 miles to a tank and these tires were the exact same ones I used to have on my 05.

SO my question is where can I start to figure out whats causing the loss in fuel economy. Once I get my emission test tomorrow im pulling the factory exhaust and installing the turbo back Billy Boat 4 inch exhaust and the cat delete will be installed.

Anywho, Im also going to do a full flush on the coolant as well as the previous owner decided to install prestone green coolant no the ford gold coolant. Then Ill do a full fluids flush.

Oh I also forgot that I notice that when I do put it to the floor its feels almost like sometimes its not wanting to and it will not down shift from fourth into third or fifth into fourth where my 05 would. Is there a possibility that there is a firmware upgrade for the ECU and PCM or the BCM?

 

Since it's new to you, are you putting in ~40 gallons @ fill-up?
Just wondering if perhaps the tank isn't getting emptied.

Use GPS to see how far off your speedometer and odometer are.
Are you driving 80+ on the highway?

These are things that effect MPG.

 

Im usually filling up around the 1/4 tank level but the last two fill ups I tried to squeeze out as much as I could from her and didnt break 300Miles.

Im usually not hitting 80, Im floating around the 65-70mph.

 

Your speedometer is off. But you probably did lose afew mpg with the larger tires. Put 75psi in them.

 

damn your getting V10 MPG :-p lol

 

Hi, welcome to the 6.0 Excursion. I have an '04 6.0 Ex and I usually get 600-700 miles to a tank, and 300-400 if I pull my travel trailer.

I did have a brake problem once that caused my mileage to go way down. One of the calipers was sticking and the brake was lightly applied all the time. The cure was nothing more than pulling the caliper and cleaning the rust from the pins and replacing it. I only knew it for sure because it was a front caliper and once it stuck in a tight applied condition which lead to pulling to one side. I would think a rear caliper would do the same pulling but not as noticeable in the steering.

It's just a thought but it made a huge difference in MPG without really noticing anything was wrong with the vehicle.

 

There is an OEM upgraded parts kit for the sticking front calipers its a known problem. a search will find you all the needed info. If your FICM has an updated flash it can kill a few mpgs easy. go to Power Hungry Performance and get the FICM flashed to a better version... Ford did the MPG and performance killling update to reduce warranty claims

 

I didn't know that! I'll have to look that up. Also the flash thing. When the dealer replaced my EGR Cooler and Oil Cooler I noticed a drop in MPG. I didn't realize they were pulling that sneaky trick, thats' the first I read of that. I don't have a flash tuner yet. Are you saying I can download a flash from Power Hungry Performance online and flash it with something like an SCT tuner? What if I buy an SCT and download Matts custom tunes. Is that basically doing the same thing as the tunes from PHP? So many options and so many different opinions...Thanks for the info.

 

no the FICM (Fuel Injection Control Module) was removed from the PCM on the 6.0 engine. PHP will send you the programmer and the files to reflash your FICM then when you return the programmer you get your deposit back for the Programmer.. here is the link Power Hungry Performance - FICM Reprogramming And I can gurantee that your FICM was re flashed by the dealer when you had the EGR and cooler work done...