Gentlemen,

Does anyone out there have any knowledge of reasonable (not polyrazmatazz) techniques for improving fuel mileage?

Does synthetic gear lube help? Do other synthetic lubricants help in this area?

Is there any way to advance spark timing on a 4.0 91 engine (no distributor)?

My van gets good mileage now, driven carefully I can get almost 20 in mixed driving with 26 or so on the highway. My computer reads about 10% high but the numbers have been corrected. a/c on

Ken

 

Yes fully synthetic lubes do help fuel millage and longevity of components. It is a higher quality of lubricant than Dino oil. With Fully Synthetic oil (Mobil 1, Amisol, Red Line, Royal Purple) there is less friction, less unwanted heat, and Less foaming which also generates more HP/TQ.

And now days it is more cost effective to purchase Syn vs Dino. 5 qts Castrol GTX= $11 every 3k mi, 5 qts of Mobil 1 = $20 and will last 10,000+ mi before needing changed (filter changed every 2k mi)

Terry Haines (former Ford Design Engineer and creator of the Ford Contour/Mystique/Mondeo) has been using mobil 1 in his vehicles for over 20 years and swears by it.

His imput on Syn oil:
http://www.fordcontour.org/index.php?showtopic=3797

Instead of copy/past 5 pages worth of talk, follow this link and read everything you wanted to know about oil:

http://www.fordcontour.org/index.php?showtopic=4160

And if you want more info, read this book:

http://www.motor-oil-engineers.com/

Yes, put 91/93 octane in, and the computer will automaitcally advance the spark. But the tradeoff in cost for premium would not really be worth it.

With Ford's DIS systems, after startup, the computer will advance the timing until the knock sensor detects knock, then it will back it off a little. That is why DIS systems are more fuel efficient than your normal Dist system. So if you are running 87 octane, the computer will spark at optimal time for that grade of gas.

 

Ken:

20mpg mixed driving and 26mpg highway driving for a 4.0L are unbeatable. My AWD 4.0L does about 17mpg mixed and 21mpg highway and I keep my van in top shape. I don't think you can improve on it any more without spending tons of money.

My brother just bought a 2005 Sienna Van with 3.2L engine. Even that thing gets only 20mpg city/26mpg highway. You are already at the very upper range of efficiency, it can only go down Why mess with perfection

 

Ken, synthetic oil is excellent, however, the key is to change your oil on time. Using a quality oil, even dino oil, use a 5w30 or 10w30 viscosity. Oil thicker than that (1ow40 on up) kill fuel mileage when cold, and pump much slower when cold. Also, make sure your tire pressures are up, and that the front end is aligned correctly. If your van has even a slight camber issue, or toe issue (+ or - ) the added resistance will ruin maximum fuel MPG. With the high cost of gasoline now, keep our Aerostars tuned up! Ed

 

Does the 4.0 1991 aerostar engine have'a knock sensor, I have never been sure of that.

Are you sure it uses that system?

Ken

 

I am 99% sure it does. When Ford introduced the DIS system on the 1989 Taurus SHO and Thunderbird SC, it required the knock sensor for timing. If it went on just pure tables, then fuel millage would tank compared to a normal distributer.

It is located just under the fuel rail in the head.

 

Thanks guys, always impressed with the colective knowledge on this site.

ken