I know there is a tun of info on the spark plug problem on the f-150. Here is the problem I have and I don't know where else to look.

cylinder #3 misfires
1. swapped coil with #2 cylinder and still throws #3 misfire code.
2. Changed the plug on #3 and still the same code #3 misfire.

any ideas where to look next?

thanks
Jason

 

hate to sy it but mine ws the same, cyl 3. changed it all same s you. changed all 8, all better.....

 

wow sorry for the disaster above - ipad ..... mine was the same situation, except cyl 1. i had to replace all 8 before it felt better

 

Changed all the plugs, one broke and now it runs much better. I am still getting occational misfires. Drove 3 hours on the interstate and got 10 misfires from severa random cylinders. Is the occational random misfire normal or do I need to do something else?

Jason

 

Did you replace all the coils?

 

No just the plugs.

 

I would highly suggest replacing all of the coil packs. I have seen many people try to tackle the coils one at a time and end up losing. I wasn't happy until I replaced all of the coil packs at one time and things have been golden since.

 

It could possibly be the boots on the coils. Did you replace them?

 

No but they are in great shape still flexible and clean. I did put the spark plug grease on every boot to make sure I had good contact.

 

I had a miss on heavy acceleration, had to replace all 8 plugs (4 broke). That solved my problem. I had fouled plugs.

 

same with me replaced all. all good now

 

Those of you who had fouled plugs when you changed them out, I would be really concerned if they were fouled from excess fuel. That could be expensive if the injector stuck open and the engine hydro-locked. I would be proactive and check the source of fouling and get the cause fixed as well to avoid future problems.

 

The old style plug was a common cause of the misfires under heavy acceleration too. The new style with the larger gap at the end is what fixes that the most.

 

I did have the older style plugs. I also had 68000 miles on the truck. Dealer said Ford recommends replacing the plugs at 60000 miles. I was expecting to get 100000 miles out of the originals, with 4 breaking like they did I'm glad I didn't wait. Plus my fuel economy and pickup DID improve after the plugs were replaced. My only issue was the exhaust vapor that started seeping into the truck almost immediately after getting them done. After 3 trips back to the dealer I found information on another site that explained they needed to re-torque the plugs. They listened re-torqued the plugs and the odor disappeared immediately! I'm finally a happy camper again!!!