Too much coke
Side electrode and insulator attached to a thick layer of yellow
skirt powder, is due to the use of leaded fuel additives caused |
Hot combustion
Melting electrode, the center electrode and the side electrode of
the port portion into a molten state. Because premature ignition
timing, cooling system adverse; using low-grade gasoline, mixture
too lean; spark plug into the combustion chamber and spark plug
heat value too low; spark plug installation torque is not enough,
the outer seal leak worse
| Toner Blackened
Screwed steel face and cavity surface portion of the insulator side
skirts and black carbon electrode surface is covered by sediments,
causing severe spark plug flameout. Mainly due to the mixture is
too thick, clogged air filter, choke improper use; excessive oil
consumption, ignition time lag; prolonged low speed and the use of
high heat value of the spark plug. | Lead Contamination
Insulator skirt side white powder or yellow,brown, green, and black
lead color. Since tetraethyl lead in gasoline at low engine load
operation of the skirt adhered to the end surface of the insulator,
when the engine speed, high speed, full load operation, the
temperature increases further, the spark plug insulator formed on
the surface of the conductive lead compound due to temperature
increased with the increase, eventually leading to fire the spark
plug. |
