Yesterday I was headed for a Dr appointment and about half way there the engine in my 02 F150 started misfiring really bad. I made it to the appt and back home noticing that it missed really bad at idle and at low rpm but seemed to run well at higher rpm. So, I used 2nd gear on the streets on the way back to keep the rpm up. I suspected the secondary ignition due to the way it was missing. Checked the codes and it indicated a misfire on cyl #5. I swapped coils with #1 cylinder and it didn't help. So I changed the plug and that got rid of the misfire. The plug was crusty and looked like it needed replacement. I installed new Motorcraft plugs 50k miles ago at 119K miles. I used anti-seize and tightened to approximately 28 ft lbs using my calibrated arms/hands. The plug was so tight that I sprayed penetrating oil down the hole and let it sit for a while before breaking it loose. So, I think it may be safe to say it's okay to use anti-seize. The engine has been missing a little at idle for a while and I had bought new Denso iridium plugs from rockauto and had them in the garage. Now, I need to change the other 7. Just thought I'd let you guys know about my experience.

 

Mine's an '02 5.4, bought 4 yrs ago. Still learning these. Think I read, 100,000 for plugs. My misfires & bad performance were from a heater core hose failure, due to a v minor, intermittent headgasket leak. Took out 2 cops. 2nd gear - yup.

 

Well, I drove the truck yesterday shopping and it started misfiring again, not as often as before so I suppose the coil was the biggest part of the problem after all. I ordered a set of Motorcraft cops from rockauto and will change out all of the cops and plugs when they arrive. Twenty years and 170k miles, I suppose it deserves new cops and it definitely needs new plugs from the looks of the one I replaced already. I'm wondering now if the Motorcraft Platinum plugs I bought from Advance Auto 50k miles ago were chinese knockoffs.

 

> The plug was crusty and looked like it needed replacement.

Black, tan, or rusty iron looking crust???

 

Gray. It's not losing any coolant and it's not burning oil. Never have to add coolant and 5k miles on a qt of oil, as good as it's ever been. And the fuel trims are perfect. I'm thinking about giving it some new O2 sensors though. It still has the originals.

 

Grey crustiness... above my paygrade... injector?!?

 

Gray crust can be aluminum deposits, I'd borescope that cylinder and maybe replace the injector. Could be running excessively lean.

 

Aluminum could sure aid a misfire...!
But rings ate not. Sleeves are not. Pistons ate aluminum then, is all I see left.

 

I drove it yesterday thinking it would miss and set a misfire code. But, it didn't miss and no code. So, I'll wait for the cops to arrive and pull the rest of the plugs to see what they look like. I'm retired and have another vehicle to drive when needed.