5.0 Spark Plug Condition

[Houston Kid]

I know not a Mustang but a 5.0 none the less and I am not on any F-150 forums. Take a look at the plugs from my truck. 2011 F-150 5.0 with 107,xxx miles on the clock. Gas millage lately started to suck a bit so I figured time to change the plugs. First time for a spark plug change. The #3 (left in pic) and the #2 (right in pic) were very dirty. The middle plug is how the rest looked or even a bit cleaner than that. The gap was at .059 on all plugs which is well past spec. I gaped the new ones a .045 and millage is back to 18.5+ on the highway.

#3 took zero force to remove. No breaking it loose, it immediately started to spin with minimal force applied. Looking at the burn residue on the upper part of the threads. I think the plug was not fully seated. I bought the truck CPO with 60,xxx miles on it. I doubt that plug has been like that for almost 50,000 miles.

Anyway, the black stuff on 2 and 3 is thick like a crusty tar. Any thoughts? Rings going bad, injector bad????

Knock on wood, zero issues with the truck other than the decrease in millage.

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[F1scamp]

Looks like used spark plugs to me...

 

[GTBOB]

What he said ^^^^. I wouldn't worry about the oil on threads. Probably helped getting them out better! That is a huge gap though, will definitely run better with a new set.

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