1 Spark plug coil is brown - should I be concerned?

[john123drury]

Hey gang - 2005 4 Runner V6. Today I went to do some routine maintenance and change the plugs. Of course everything goes perfect until I reach the last plug. When I took of the coil connector, this is what I saw:





Now I will say that the plug itself was just a little bit loose (didn't take any effort to unscrew it). So i'm HOPING that is the reason for the brown burn marks I am seeing.

Just wondering if I should be concerned about this, or if you think it truly happened simply because of the loose plug. Appreciate your input gang!

 

[NuclearN8]

looks like combustion by-products to me, so the most logical answer is over time they snuck by the spark plug threads since it was so loose... I wouldn't sweat it if you're not getting any codes and everything else is normal. button her back up with proper torque values.