INSPECTION
Check the electrodes and inner and outer ceramic insulator of plugs, noting the type of deposits and the degree of electrode erosion.
Scheme 8
- Spark plug gap
- Carbon accumulation or wear
- Crack
- Damage
- Damaged gasket
Normal
Brown to grayish-tan deposits and slight electrode wear indicate correct spark plug heat range.
Scheme 9
Carbon fouled
Dry fluffy carbon deposits on insulator and electrode are mostly caused by slow speed driving in the city, weak ignition, too rich fuel mixture, dirty air cleaner, etc.
Scheme 10
Oil fouled
Wet black deposits show excessive oil entrance into combustion chamber through worn rings and pistons or excessive clearance between valve guides and stems.
Scheme 11
Overheating
White or light gray insulator with black or brown spots and bluish burnt electrodes indicate engine overheating. Moreover, the appearance results from incorrect ignition timing, loose spark plugs, wrong selection of fuel, etc.
Scheme 12
| IMPORTANT | Avoid using a plug cleaner because of the spark plug with a platinum tip. |
Check the following using a tester. Replace if defective.
Scheme 13
- Secondary coil resistance IMPORTANT: If the resistance is extremely low, it indicates the presence of a short-circuit. Ignitor is integrated with the coil. Therefore the resistance of primary side coil cannot be measured. Specified resistance: [Secondary side] Between (A) and (B) 11.2 kO+/-15% Between (C) and (D) 11.2 kO+/-15%
Check the following items
- Damage to cords, deformation, burning or rust formation of terminals
- Resistance values of cords
Resistance value
#1 cord: 7.1 - 12.1 kO
#2 cord: 12.1 - 19.9 kO
#3 cord: 7.7 - 13.0 kO
#4 cord: 12.3 - 20.2 kO
