Can someone help?
I have a 1997 Ford F-150 ext. cab Lariat 4x4 4.6L 73K miles
I have but duels, K&N air intake, and performance chip in this about 14 months ago.
In the beggining I was getting 15mpg, now about 4 months ago the milage stated going down now its at 10mpg.

I have tried a tune up putting a new fuel filter, spark plug, and wires. It seems it started getting bad after this, also I had the tranny services. All the milage problems started after it also got cold. Indiana.

Should I try an additive to clean the injecters?

What could the problem be? Any ideas?
Thanks

 

Winter gas has ethenol in it to lower emissions in the winter, it will also make your gas mileage drop, how much, I couldn't tell you, try some octane boost see if that help's any...........

 

I ALSO NOTICED THE RPM'S ARE HOLDING HIGHER NOW WHICH WOULD CAUSE THE MILAGE TO GO WAY DOW.

AT 80MPH I WAS RUNNING AT 2200RPM
NOW ITS MORE LIKE 2600-2700RPM

I JUST HAD THE TRANNY FLUSHED AND SERVICED, IS THIS COMMON IN THE WINTER?

ANY IDEAS?

THANKS

 

Makes it sound as though it isn't shifting into overdrive, if you have the od on off switch try turning it off while driving and see if the r's go up, if not then that's probably the problem.

 

I agree it sounds as if it's not getting to the 4th gear (overdrive). Is your overdrive light on? Is it flashing?

You may want to have a diagnostic run on your tranny. This has nothing to do with fuel. RPMs are soley based on the engine speed and the only thing that can change the RPMs when at a certin speed is the tire size, gear size, what gear the transmission is in, clutch engaged or partial engaged, etc...

 

The overdrive works fine the button works the light works. If I'm doing 80 at 2200rpm to 2700rpm depending on the day and I take off the overdrive the rpms goto 3000 something...

thanks for your help