Hello from Michigan,
Well, after replacing the pre cat O2 sensor, the mpg's initially jumped up 40%, but then settled down to about 20%. Before replacing the sensor, mpg was 19 to 20 average. Now it is 24 to 25. After resetting the computer again, I am now getting a code for the post cat sensor heater circuit. After talking with Dan Merrick, scanned the computer while driving and found the post cat O2 sensor stable at 447 mV - should be changing, just not as frequently as the pre cat sensor.
Bottom line, I need to replace my post cat sensor.
Food for thought. Per Dan M., especially for Fords, your O2 sensors are critical for fuel management, and even if there are no codes, on vehicles that are not responding to the groove with mileage gains, your O2 sensors might be holding the gains back. I have grooved 6 Fords and have had little success with MPG gains. Possibly time for O2 sensor replacements.
Looking forward to the future!
Scott Castleberg
Pellston, MI
Gadgetman Michigan
