Daniel L. Katz wrote:
> badly fouled plugs provide a shunt path bypassing the gap, and the voltage
> may never rise high enough for a spark to jump the gap, causing a miss.

I saw this in action, once.  I tested a plug that my neighbor had pulled
out of his BMW.  It literally sparked from the center electrode to the
carbon-coated insulator, instead of to the outer electrode.

--

David Brodbeck, N8SRE
'82 VW Diesel Westfalia
'86 Volvo 240DL wagon