I keep getting a Cyl 4 misfire on my '98 F150 4.6L V8. I can feel it in the engine when I'm driving so I know it's there. Plugs and wires were replaced about a month ago and it was running fine for about a week, then it started misfiring. I have double checked the plugs and the wires. I even bought an ignition coil pack for the side with #4 wire/plug and replaced that, and it did not fix it. I'm stumped on this.. Does anybody have any suggestions??

 

Since you just replaced the wires and plugs, I would start by replacing those first just on that cyl. I've had a new plug that was bad and it looked fine. Good luck.

 

I had a similar problem where I replaced the wires and about two or three days later a misfire developed. Messed with it for about a week and took it to the dealer. Turns out one of the plugs had a cracked insulator and was arcing on the block. Can be pretty hard to see.

 

Thanks. It seems like the cheapest and best route to go thus far. I'll let you know what happens.

Thanks again.

 

put some sealant around the outside of the boot, keeps the moisture from the ac compressor out. that kills em.
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94 ford f-250 4x4 7.3 diesel auto tranny rebuilt by myself
97 f-150 305 auto
01 excursion 4x4 v10
84 f-150 351 winsor 5 speed

 

Make sure the heater hose isn't dripping into the plug pocket. Common on these trucks.

 

What wires are you talking about replacing?

 

plug wires. 97/98 4.6L have coil packs, not COP's.

 

You mean, the 4.6L engines have full-up actual old style plug wires coming out of the top of the coil packs? Guess I was just confused. The 5.4 doesn't have wires, but I get the 4.6 does.

 

i had the same problem....its the fuel injector ...guarenteed..i changed all and ...it is definately the injector