Ignition System

Spark Plug Inspection

 4-18  

  1. Inspect the electrodes and ceramic insulator.

Burned or worn electrodes may be caused by:

  • Advanced ignition timing
  • Loose spark plug
  • Plug heat range too hot
  • Insufficient cooling

Fouled plug may be caused by:

  • Retarded ignition timing
  • Oil in combustion chamber
  • Incorrect spark plug gap
  • Plug heat range too cold
  • Excessive idling/low speed running
  • Clogged air cleaner element
  • Deteriorated ignition coils

  1. Do not adjust the gap of iridium tip plugs (A); replace the spark plug if the gap is out of specification.

Electrode Gap:

Standard (New):

1.0 - 1.1 mm

(0.039 - 0.043 in.)

Service Limit:

1.3 mm (0.051 in.)
  1. Replace the plug at the specified interval, or if the centre electrode is rounded (A). Use only the spark plugs listed below.

Spark Plugs:

IFR7G-11K (NGK)

SK22PR-M11 (DENSO)

  1. Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight. Then torque them to 18 Nm (1.8 kgf/m, 13 lbf/ft).