4 bad coil packs at once?
 

my '05 F-150 with 4.6 L started running rough and check engine lite came on. ran the truck for about 80 miles after this happened, no choice. had the codes pulled at autozone and they told me they read as follows: cylinder 3 misfire, coil pack A bad, coil pack F bad, coil pack G bad, and coil pack H bad. would 4 coil packs go bad at the same time, or is there another problem causing this? if anyone could tell me which coil packs these are it would help a lot. also wondering if there is a way to check the coil pack with an ohmmeter? thanks for the help.

Usually when the COPS go bad, they go bad all at one time. You didn't say how many miles on the clock but I'll assume about 50,000 miles. That's an early failure for COPS as they generally go 100,000 or more miles before failing. If you are beyond warranty, I'd suggest buying them off of ebay from one of two suppliers. Uneek and Global both have fully warranted sets of 8 COPS for about the price of one Ford 90 day warranted COP. They have quite a following of happy users and no, I am not affiliated with either. Another issue you might have is that the plugs were not gapped correctly. My 2004 4.6 had gaps in excess of .075 from the factory. Larger than spec gaps causes the COPS to work harder and fail sooner. I'd change plugs while you have it apart. The 4.6 is a standard one piece plug and is a pretty straight forward change. You'll need dielectric grease to use on the insulator of the plug to seal out moisture, otherwise it's pretty much like changing any other plug. The Tritons seem to like Motorcraft plugs over others- YMMV.

I would have to disagree with you on when coils go bad that they do it all at once I have had two go out one at 48000 and one at 56000 #4 and # 8 .And have seen on several forums that once one does go out then starts a snow ball effect.The last one done at the dealer ,the tech told to expect that because when you do have one go out it causes the others to to compensate for the weak or dead one.

I would also disagree coils should never all go out at once I would look for water intrusion into the spark plug wells when the coils get miles on them the boots shrink and don't seal as they should water will migrate even overnight as condensation if you find water droplets or rust on the boot or plug replace the boots they are availble without the coil they should be replaced everytime you change your plugs

hope this helps

I doubt all coil packs would go bad at once. I would look over the codes again, typically a bad cop will produce a code that reads p304 or something similar for a misfire. You may be receiving multiple codes. Also driving for 80 miles with a substantial misfire can damage your cat converter so perhaps you may have a bad cop and now a bad cat on the same side of the engine.