WHILE DRIVING THE VEHICLE MADE A LOUD BANG AND SMOKE BEGAN COMING OUT OF HOOD. ONCE WE GOT THE ENGINE TURNED OFF AND THE EMERGENCY WAS OVER WE DISCOVERED THE SPARK PLUG HAD BLOWN UP. WHEN IT BLEW UP THE HEAD BECAME STRIPPED AND WE HAD TO HAVE A PLUG INSTALLED INTO THE DEFECTIVE HEAD AND REPLACE THE COIL. I HAVE SINCE FOUND OUT THIS IS A VERY COMMON PROBLEM WITH FORD EXCURSIONS. *TR