was having some idling and starting issues with my 99 f150 (4.6l--v8) which lead back to a bad ignition coil. so changed the coil two weeks ago and that totally cleared up every problem i was having until early last week. died at a stop sign and this is reminiceint of the behavior before. the exception here is that it would not restart after sitting for a few minutes. also, there was a small amount of smoke. i was left with an immobile truck and the lingering smell of what i can best describe as 'burning army men'.

then, i relaced the cam shaft sensor, as a recent code check indicated needed to be done, but was still experiencing the same problem with the same sounds. the starter engaged but then nothing happens. my oil temp, theft (flashing) and battery lights then turned on. upon further investigation i identified the area causing the problem, once again, as the ignition coil. it had cracked open, and melted from the inside out. i replaced it not once, but twice that day with the same results. i don't know what could be causeing this to happen, but i know it's not the coil.

having exhausted my limited automobile knowledge i finally decided to take it to the shop where they told me there was some hardend 'residue' in the mount for the ignition coil that may have been causing it crack, and inevitably blowout, when tightening down the bolts. this was also the cause of the blown fuse (specifically a 30amp minifuse located in position 30 in the cab fuse panel which powers the passive anti theft transceiver, cluster, ignition coils, powertrain control module relay).

i was skeptical of such a simple fix, but it drove fine. unfortunately that only lasted a day before frying the new coil, blowing another fuse, and loosing all powersteering going 70mph. i managed to safely pull it to the side and since i was traveling i got a new ignition coil and replaced the fuse just to get it off the side of the interstate and hopefully home. got 2-3 miles up the road before the coil melted out again. the only things i can think this could be would either be the relays or the spark plugs/ignitors. im not terribly skilled so any other ideas would be greatly appreciated...?

 

Usually any time an electrical coil overheats is due to excessive current going through the coil. For starters I would suggest checking your charging system for possibly overcharging.
Then another consideration would be to check the spark plug connections for open connections or gaps other than the normal spark plug gaps.
If I can think of any other reasons, will post them.