Check spark plugs:

• Inspect at every 8000 km (5000 mile) service interval.

• Replace every 16,000 km (10,000 mile) service interval.

1. After the engine has cooled to room temperature remove airbox assembly. See 1.4 AIRBOX AND AIR FILTER.

2. Lift fuse block off the retaining bracket and move to side.

3. See Figure 1-49. Remove rear coil fasteners (1).

4. Detach connector (2) [83R] at rear coil, [83F] at front coil.

5. Pull coil and boot assembly straight up to disconnect spark plug.

6. Using a spark plug socket with plug retaining sleeve, remove spark plug.


Remove battery for access to front spark plug. See 1.7 BATTERY MAINTENANCE.

7. Remove front plug following steps 3 through 6.

1. Fasteners

2. Connector [83R]

Figure 1-49. Rear Cylinder Coil

1. Fasteners

2. Connector [83R]

Figure 1-49. Rear Cylinder Coil

Figure 1-50. Plug Top Coil

8. See Figure 1 -51. Compare your observations of the plug deposits with the descriptions provided.

a. A wet, black and shiny deposit on plug base, electrodes and ceramic insulator tip indicates an oil fouled plug. The condition may be caused by one or more of the following: worn pistons, worn piston rings, worn valves, worn valve guides, worn valve seals, a weak battery or a faulty ignition system.

b. A dry, fluffy or sooty black deposit indicates an air-fuel mixture that is too rich, engine idling for excessive periods of time and/or enrichener usage for excessive periods of time.

c. A light brown, glassy deposit indicates an overheated plug. This condition may be accompanied by cracks in the insulator or by erosion of the electrodes and is caused by an air-fuel mixture that is too lean, a hot-running engine, valves not seating or improper ignition timing. The glassy deposit on the spark plug is a conductor when hot and may cause high-speed misfiring. A plug with eroded electrodes, heavy deposits or a cracked insulator must be replaced.

d. A plug with a white, yellow, tan or rusty brown powdery deposit indicates balanced combustion. Clean off spark plug deposits at regular intervals.

9. If the plugs require cleaning between tune-ups, proceed as follows:

a. Degrease firing end of spark plug using ELECTRICAL CONTACT CLEANER. Dry plug with compressed air.

b. Use a thin file to flatten spark plug electrodes. A spark plug with sharp edges on its electrodes requires 25-40% less firing voltage than one with rounded edges.

c. If the plugs cannot be cleaned, replace with No. 10R12A spark plugs.

10. Check electrode gap with a wire-type feeler gauge. Bend the outside of the electrode so only a slight drag on the gauge is felt when passing it between electrodes. Proper gap measurement is 0.89 mm (0.035 in.).

11. Check condition of threads on cylinder head and plug. If necessary to remove deposits, apply penetrating oil and clean out with a thread chaser.

Figure 1-51. Typical Spark Plug Deposits
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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