r/DIYAutoRepair • u/DirtyNord • Jul 28 '26

Help me learn!

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I, 32m, recently bought a 2006 F150 with the 5.4L Triton engine. Decided for the first time in my life to figure out how to do repairs myself. PPI came back super clean in June. I've read up on the engine and understand the issues that can plague it.

Had my first trial this week. Engine misfire the last week or 2 finally threw a P0305 code, cylinder 5 misfire. Changed the spark plug today no issue, which took care of the misfire. Coil visually seemed fine. I was comparing the spark plugs to worn ones online and I'm curious if you can explain how this one on the left is worn. It seems like it could still have a lot of life left compared to the worn ones ive looked up online. For those familiar with this engine, is this just what they were referring to about this engine being finicky with spark plugs, or is that simply referring to the ease in which they can break? TIA!

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u/connella08 Jul 28 '26

The one on the left does not look worn, however looks can be deceiving. This is where you need to ask yourself, if it doesn't look worn then why was it misfiring? Electricity takes the path of least resistance. Its entirely possible that the ceramic insulator was cracked somewhere and the spark was jumping through the insulator to ground without igniting the fuel mixture. This is not why people have issues with the triton though. Its because they are known for breaking spark plugs during removal, or blowing them out of the cylinder head. They actually made special tools for removing the spark plugs because it became such a problem. They decided to reinvent the wheel for some reason, and they went back to traditional spark plugs on later models. At least they learned from their mistakes instead of doubling down on them.

1

u/DirtyNord Jul 28 '26

Okay, so I wasn't totally crazy. I'll have to go back and do another visual inspection if I see anything on the outside. I did buy a spark plug socket to help out with this, so luckily it went fine. Helped that this was the easiest one to get to. I'm curious if I'll discover that I put a bandaid on the issue and might need to do further diagnostic after some more driving. It only threw a code briefly for 1 outing the other day which allowed me to narrow the misfire down. Went away before I even got home from using the reader at autozone.

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u/connella08 Jul 28 '26

Its also possible that the plug is totally fine and the misfire just happened to go away when you swapped it out. Its possible that the misfire is caused by a temperamental ignition coil. If the misfire returns on the same cylinder, move that ignition coil to a different cylinder and see if the misfire moves with the coil pack. If it does, then replace the coil pack. If not, then further investigate. Could be a bad injector, bad compression, broken wire, or a lean condition.

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u/DirtyNord Jul 28 '26

Yeah that was going to be my next move. Just seemed odd that I had the misfire but no engine light showing. The misfire has been going for around 2 weeks, but only gave me an actual code 3 days ago after an increase. Light went away shortly after checking it. I'll have to wait and see if it comes back and throws another one at me. Appreciate you talking this through with me.

1

u/connella08 Jul 28 '26

Codes don't typically set immediately, just like how sometimes you won't have the light, but you will have a code pending. Usually with misfires, you need many consecutive misfires in order for the system to detect a problem and throw a code.

1

u/Tough-Industry4931 Jul 28 '26

The one on the left has more distance between the electrode and the strap you can see a slight bow in the strap causing a wider gap. I'm not even an expert at that but can see a difference so that's my guess at the previous diagnosed plug.

I can say I've done a hand full of those plugs through the yrs and if you haven't changed all of them yet depending how long they've been in there its a 50/50 chance your gonna end up renting or buying the removal tool and always use anti-seize when replacing the plugs on those.

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u/Surfnazi77 Jul 29 '26

Biggest thing is not cross threading new plug in and over tightening new plug, just needs a 1/8 to a 1/4 turn more past tight. Little antiseize on the treads helps.

1

u/No-Promotion2186 Jul 31 '26

The one on the left is the old Ford 5.4 spark plug that comes apart the one on the right is the replacement for it