I have a 97 F150 4.6L. It has 112K mi. and has begun running rough on idle and worse on acceleration. Code reader at AutoZone showed a misfire on cyl. 4. With the mileage, everyone I spoke with agreed that plugs and wires were the likely culprit. I had the plugs and wires done today at the local Ford dealer, and after $320 I still have the exact same problem I had with my old plugs and wires. The service manager claimed they did not do any further scans or tests because all I had requested was new plugs and wires. I feel fortunate that they did not take any more of my money, but I'm sitting here with the same problem I had before with no resolution. I am the original owner of this vehicle since 7-96, and have been quite pleased until now. Any advice or ideas are greatly appreciated. Thanks

 

Sorry to hear about your bad experience with your dealer but unfortunately with alot of flat rate shops where the techs are paid by the job thats what happens. Now usually what I find with the early 4.6's is that the coolant hose to the heater core is leaking causing the miss but the tech should have noticed that and said something to you, in any case the next thing I'd try is grab a cheap spark tester from your local parts store and check to see if you have spark to #4 cyl as you might have a coil thats not firing.

 

The problem was in fact a bad coil pack. Dealer replaced the coil pack and now cylinder 4 is up and running with the rest of them. It sure is nice to have that smooth running truck back again!