MY WIFE WAS DRIVING WITH OUR INFANT SON AND OUR TEENAGE DAUGHTER IN OUR 2003 EXPEDITION XLT 4.6L 2X4. SHE HEARD A LOUD POP AND THE VEHICLE LOST POWER AND STARTED SMOKING AND SHAKING VIOLENTLY. SHE THOUGHT THE EXPEDITION WAS GOING TO BLOW UP. WE HAD THE EXPEDITION CHECKED OUT AND THE CYLINDER NUMBER 7 SPARK PLUG BLEW OUT. THE ALUMINUM THREADS IN THE HEAD GAVE AND THE SPARK PLUG BLEW OUT, THE INJECTOR KEPT SPRAYING RAW FUEL AND THE COIL IGNITED IT. WHEN ALL THIS HAPPENED IT BURNED THE IGNITION COIL, COIL BOOT, SPARK PLUG AND THE COIL HARNESS. NOW WE WERE TOLD WE WOULD HAVE TO HAVE THE CYLINDER HEAD REPLACED. WE LOVE OUR EXPEDITION AND I CONSIDERED BUYING A NEW ONE, BUT I DON'T KNOW NOW. *KB