Other information:
Acceptable Noise, Vibration and Harshness (NVH)
Noise is any undesirable sound, usually unpleasant in nature. Vibration
is any motion, shaking or trembling, that can be felt or seen when an
object moves back and forth or up and down. Harshness is a ride quality
issue where the vehicle's response to the road transmits sharply to the
customer. Harshness normally describes a firmer than usua..
Inspection
NOTE:
Dropped spark plugs should always be discarded.
Unfired
An unfired spark plug should appear very clean
with a pure nickel finish to the threads and ground strap. The center
electrode ceramic insulator surface is often a matte or dull finish and
pure white in color. The external primary insulator is often a polished
white ceramic with appropriate stamping ..