Hi, everyone I am new to the site and looking for any tips, on squeezing more mileage out of my 03 expedition 5.4. I have already put cold air, royal purple oil over the year and today red line syn trans fluid. We are leaving Sat for vacation (400 miles) and hoping to see alittle change (a mile or two would be great).

 

Just more of my $.02 worth, but the colder air is gonna make the air more dense, so the MAF is gonna measure more air mass, and therefore its gonna require more fuel mass to maintain a 14.7:1 air/fuel mixture.

Now if your trying to extract the last 0.5 HP out of the engine when the pedal is in the carpet, it will prolly make a difference.

But if your trying to squeeze the last 0.1 MPG out of your rig, if you can throttle back so that you are using the original amount of air mass for the same speed/load, shouldn't make any difference.

My experience is where you drive (stop and go vs. open road, hilly vs. flat terrain, etc.) and how you drive has the biggest impact on fuel mileage. Keep a light foot on the pedal, getting it into high gear as soon as possible, and maintain the highest vacuum reading (which maximizes spark advance) and you will see an improvement. I'd recommend getting a vacuum gauge and/or a scan tool that displays instantaneous MPG and you'll be able to see what works best for where you drive.

 

What Jim said. Plus, make sure you take any extra weight out of the vehicle (i.e. third row seat, junk that always seems to collect in the back, etc.) and make sure your tires are inflated properly. Making sure your alignment is correct will help too, so that you're not wasting energy on scrubbing tires. But above all, the thing that helps the most is: take it easy on the loud pedal.

 

Also, if you're on the highway, maintaining a steady speed with cruise control or if you're just good with the pedal helps too. From 40 miles north of Atlanta to St. Simons Island I managed 21 mpg in my '98 Expedition 5.4 liter. I was easy on the pedal, have all clean filters on the car and had the tires inflated right and balanced and the alignment in check. Good, fresh plugs also. And no, with my experience at least, platinum or iridium plugs do not improve performance or fuel economy, they only extend the useable life of the spark plug. And unless your car is just very restricted, which most Ford trucks are not, CAIs will not make a difference worth the $250-400 it will cost you.