First question I have is... Did you reset the Check Engine light by clearing
the trouble codes? Second question... Does your Ford Taurus's check engine
light re-illuminate after a reset soon as you start the engine? Have you
rescanned the OBD II for new trouble codes; or perhaps the same trouble code
(P0301) reappearing?
If the Check Engine light turns on again after resetting and you have
ensured the engine ignition system is working properly, you may want to run
the ignition system on an ignition oscilloscope. The oscilloscope will show
small variances in the ignition pattern which might not be apparent to you
by simply listening to the engine or feeling for misfires.
If the oscilloscope shows no ignition system defects either, the next
component you might want to suspect is your Ford Taurus's camshaft position
sensor. Why the camshaft position sensor? Believe it or not, the way your
Ford's OBD II system learns about a misfire or senses a misfire is by the
"skip in the beat" seen by the Camshaft Sensor at the exact moment the
misfire occurs. So if all else fails and you can't get rid of the Misfire
Trouble code, your Ford might not have a misfire at all and just a faulty
Camshaft position sensor.
