ABOUT 3DAYS AGO MY F150 TOOK A SPELL OF MISSING ,I FOUND OUT BY A FRIEND WHO HAS A HAND HELD CODE READER THAT THE #8 CYL HAD A CODE PO358 IGNITION COIL CIRCUIT FAULT.I BOUGHT A NEW MOTORCRAFT COIL FOR IT . IT RAN FOR ABOUT 45MIN THEN FAILED.I TOOK IT BACK AND GOT A NOTHER ONE .THIS TIME THE COIL SMOKED AND BLEW THE FUSE TO THE PCM. I THEN TOOK THE COIL FROM # 6 CYL AND PUT IT ON #8 STARTED THE ENGINE ,THAT COIL SMOKED AND BLEW THE FUSE.I HAVE NO WATER LEAKS WHAT SO EVER ON THE TOP OR ON THE BOTTOM (I.E. HEADGASKET) I DON'T KNOW IF THERE IS A DIODE SOME WHERE IN THE LINE OR IN THE PCM IT SELF. ALOS I REPLACED THE SPARK PLUG AFTER IT SMOKED THE 2nd COIL .
SO FAR COUNTING THE FIRST ONE IT HAS SMOKED 4 COIL. IF ANYONE HAS ANY IDEAS OR HAS KNOWN ANYONE WHO HAS DELT WITH A PROBLEM LIKE THIS PLEASE LET ME KNOW I AM AT MY WICKS END THANKS! MAINTAINER

 

something is probrally grounded out

 

Did you change the plug? maybe it's bad.
Jimmy

 

You must have a bad pcm cause the output transistor is sending out too much voltage to fire the coil. most likely. You did pull the plug and look right?