After a sudden loss of power and serious miss in the firing order I check out my plugs. Hehe, they're in critical shape, time to bury them.

A couple of the plugs seem to have a blackish, sooty, gritty deposition on the rim outside of the center electrode??? Furthermore, on those same plugs the insulation sleeve that directly surrounds the center electrode was either cracked or completely missing.

Any hypothesises on the cause or causes. Is it possibility a lean condition from fuel restriction? High temperatures in the cylinder due to carbon build? Combination of the two?? HELP....please!

This is a DB with 170,000miles on the ticker.

 

bump for the working folk

 

what mods have you done to the car?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by evolve &raquo;</TD></TR><TR><TD CLASS="quote">the insulation sleeve that directly surrounds the center electrode was either cracked or completely missing.</TD></TR></TABLE>

Overly advanced ignition timing.
Wrong heat range of plug to begin with.

 

With the spark plugs, I've tried near all heat ranges recommended. This was after timing was checked to be proper.

I don't have any mods...It's fired plugs since I've bought it over two years ago. Of course it could have internal mods that I don't know of. That might explain improper plugs matching?

I considered timing again, it has been awhile since the last check.