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Spark Plug Inspection

  1. Remove the spark plugs and inspect the electrodes and ceramic insulator.
    • Burned or worn electrodes may be caused by these conditions:
    • -
      Advanced ignition timing
      Loose spark plug
      Plug heat range too hot
      Insufficient cooling
    • Fouled plugs may be caused by these conditions:
    • -
      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. If the spark plug electrode is dirty or contaminated, clean the electrode with a plug cleaner.
    • Do not use a wire brush or scrape the iridium electrode since this will damage the electrode.
    • When using a sand blaster spark plug cleaner, do not clean for more than 20 seconds to avoid damaging the electrode.

  1. Do not adjust the gap (A) of iridium tip plugs; replace the spark plug if the gap is out of specification.
    Electrode Gap
    Standard (New):
    1.2−1.3 mm (0.047−0.051 in.)

  1. Replace the plug at the specified interval or when the center electrode is rounded (A). Use only the listed spark plugs.
    Spark Plugs

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