What's going on with this spark plug?

[plymouthcolt]

In trying to diganose my stuttering/hesitation in low gear, I removed each spark plug wire and reseated to eliminate the easy possible problems.

When I removed the wire for #6, I saw this green corrosion inside the wire housing. How does this type of corrosion occur? All the other plug wires were fine.

So I removed the plug and saw this on the plug.





My best best guess is the wire was not seated firmly (maybe not at all) on the tip of the plug.

I am going to buy a new spark plug, but any ideas on how to remove the green corrosion from the plug wire?

Lastly how does the firing end look to more experienced eyes?

[ben parrish]

Do you live near the ocean?

[Paulporsche]

Looks like verdigris, which is a copper oxide. Brass, bronze and copper get it when exposed to air/water. Try cleaning it off. Depending on how old the plugs are, you may just want to replace them. If fairly new, I would try polishing it off and reinserting the plug wire cap w/ some dialectric grease. The plug wire may not have been clicked on properly.

The electrode end looks pretty good as long as those black deposits are not wet. If you have MTBE in your gas, that could be making them a little black. Or you may be running just a little rich, or taking too many short trips.

[dentist90]

A bit rich was my first impression, too. Electrode doesn't look worn at all, so if it's had quite a few miles should be no problem.
As far as oxidation on connector goes, check your plug wire boot very carefully for ANY sign of cuts or tears or especially melted spots which could allow water in (happens when washing car or rain gets thru grill). It looks to my eye that there may be a bit of carbon tracking right where the green letter S is on the insulator base. So if you have hesitation under load, carbon tracking and/or visible wear on boot it may be time for a new set of plug wires. Usually a cracked insulator and grounding out would cause misfire in all gears, not just low, so don't know what that's about.

[bigchillcar]

top appears to have been exposed to moisture..

[KCinBR]

I had a similar sort of greenish deposit on one of my plugs, I think it is caused by electrical arcing from a bad connection, I ended up replacing the plug connector ( the end of the spark plug wire that fits over the plug) it's fixed now