#7 plug is a different color than the others?
 

I pulled my plugs the other day to change them and when I got to the number 7 plug it was darker than the rest. It wasn't so dark that it worried me but the difference between it and the other plugs is noticeable.

Anybody have any ideas as to what this could mean? I've read that a clogged injector can cause this and mabye something to do with the valves, but I am not an expert. I have noticed a very faint ticking sound coming from the driver's side of the engine also.

Any ideas? Thanks in advance.

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1968 Fuel Injected Mustang Coupe

Are you loosing oil? I would do a compression test. It it is low on compression, put some oil it and see if it comes up. If so you have a ring problem. If rings are good, but you are burning just a little oil, I would go after valves next. If no oil, try a new plug (could just be a bad plug) and see what it looks like after a while. If it is bad, then I bet you have an injector problem.
Maybe none of these. Hope you find it. Good luck.

Thats usually associated with a lazy or clogged injector. the spray of the injector and its ability to close is off from the others(injectors). that cylinder might be on the rich side due to this; thus the color of the plug.