Spark Plug Exploded on Freeway! Why?

[ExplorGM]

Has anyone else had this happen, and is there a reason other than defective plugs?

I was driving down the freeway yesterday and I heard a loud bang and clack clack clack. At first I thought there was a chicken under my hood, but it turned out to be a spark plug that had blown its ceramic center out of the metal "housing". The end of the electrode was broken off. I am hoping that it broke off upon impact with the frame or other piece of metal outside of the cylinder!
As many of you know, I have been trying to diagnose a "missing" problem for a week or so and two weeks ago I replace the plugs and wires and the problem went away only to return last week. The plugs are Bosch Platinums which I have use successfully over the years.
If the piece broke off inside the cylinder this would explain the new missing problem! If it did though, its been in there for a while and there is probably damage to the cylinder walls and or pistons, valves etc...

Has anyone else had a similar experience,and does anyone know of a reason for a plug to do this? The metal receiving end of the spark, is fine. It did not touch the piston so contact was not the reason for the explosion.
Bummed in CA.(Moab plans in serious jepardy.)
Rick


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Rick
95 Explorer Sport Expedition
Dead Link Removed

 

[gerry]

I had the exact same thing happen with a Champion plug. I thought at first that I might have put some side-to-side pressure on it when I installed them with the socket wrench, but after looking at it closely, I'm convinced it was a defect in the plug. I was lucky in that it blew "out" and not into the cylinder, but I will NEVER use Champions again!

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2000 4x4 XLT SOHC V6

 

[ExplorGM]

Well, I found the cause.Two injectors bad and running too lean. Burned up two plugs. Burned up either the valves, or cylinders or both.
Rick

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Rick
95 Explorer Sport Expedition
Dead Link Removed

 

[damon]

Must of been really lean, thats something you usually only see with a supercharger or NOS on the car.