Ignition System

Spark Plug Inspection

 4-25  

  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. Cracked insulator
  2. Damaged gasket
  3. Worn or deformed electrodes
  4. Improper gap

    Oil-fouling

    Carbon deposits

    Cracked centre electrode insulator

  1. Do not adjust the gap of platinum 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 (0.05 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:

Engine Type Spark Plug Type
D14Z5, D15Y6,

D15Y4, D16W7

 ZFR5J-11 (NGK)

KJ16CR-L11 (DENSO)
D15Y5, D17A1,

D17A2, D17Z1,

D17Z4

 ZFR6J-11 (NGK)

KJ20CR-L11 (DENSO)
D17A5 BKR6E-N11 (NGK)

K20PR-L11 (DENSO)
D15Y2, D15Y3,

D16V2, D16W8

 BKR5E-11 (NGK)

K16CR-L11 (DENSO)
D17Z2, D17Z3 ZFR6J-11 (NGK)

ZFR7J-11 (NGK)

KJ20CR-L11 (DENSO)

KJ22CR-L11 (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).