Found an interesting problem while listening to AM 630 all news station
here in WDC.
Getting loud clicking noise. Sounds very much like spark plug noise but
when coasting at 30mph and placing the engine in neutral such that the
engine RPM drops from 2500rpm to idle, the ticking noise remains at
speed. However, as the vehicle slows down the noise also slows down. I
can rev up the engine while it remains in neutral but the speed of the
noise doesn't change. Is there some type of speed or other monitoring
devices on the wheels of the 2001 Explorer that is sending RF signals to
the on-board computer? This one is got me scratching my head.