NO.27 SPARK PLUG CONDITION [WITH WU-TWC]


27	SPARK PLUG CONDITION
DESCRIPTION	Incorrect spark plug condition
POSSIBLE CAUSE	Note • Inspecting the spark plugs condition can determine whether problem is related to a specific cylinder or possibly all cylinders. Wet/carbon stuck on specific plug: • Spark-Weak, not visible • Air/fuel mixture-Excessive fuel injection volume • Compression-No compression, low compression • The malfunctioning spark plug Grayish white with specific plug: • Air/fuel mixture-Insufficient fuel injection volume • The malfunctioning spark plug Wet/carbon is stuck on all plugs: • Spark-Spark weak • Air/fuel mixture-Too rich • Compression-Low compression • Clogging in intake/exhaust system Grayish white with all plugs: • Air/fuel mixture-Too lean Warning The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services: • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "BEFORE REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual. Caution • If there is foreign material on the connecting area of the quick release connector, it might damage the connector or the fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.


STEP	INSPECTION	RESULTS	ACTION
1	Remove all spark plugs. Inspect the spark plugs. Are the spark plugs normal?	Yes	Troubleshooting completed.
1		No	Specific plug is wet or covered with carbon: Go to the next step. Specific plug looks grayish white: Go to Step 7. All plugs are wet or covered with carbon: Go to Step 10. All plugs look grayish white: Go to Step 16.
2	Is the spark plug wet/covered with carbon due to engine oil?	Yes	Working up and down, inspect all areas related to oil.
2		No	Go to the next step.
3	Inspect the spark plug for the following: • Cracked insulator • Heat range • Air gap • Worn electrode Is the spark plug normal?	Yes	Go to the next step.
3		No	Replace the spark plug.
4	Inspect the compression pressure at suspected malfunctioning cylinder. Is the compression pressure correct?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning parts.
5	Install all spark plugs. Carry out a spark test at the suspected malfunctioning cylinder. Is a strong blue spark visible? (Compare with normal cylinder.)	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning parts.
6	Carry out fuel line pressure inspection. Is the fuel line pressure correct?	Yes	Inspect the fuel injector for the following: • Open or short in injector • Leakage • Injection volume
6		No	Zero or low: Inspect the fuel pump circuit. Inspect for fuel leakage inside the pressure regulator. Inspect for a logged main fuel line. High: Inspect the pressure regulator for the high pressure cause. Inspect for a clogged fuel return line. Inspect the vacuum hose to pressure regulator.
7	Inspect the spark plug for the following: • Heat range • Air gap Is spark plug normal?	Yes	Go to the next step.
7		No	Replace the spark plug.
8	Turn the ignition switch off. Disconnect the suspected fuel injector connector. Turn the ignition switch to the ON position. Measure terminal voltage for fuel injector terminal A. Is the voltage B+?	Yes	Go to the next step.
8		No	Repair the open or short circuit to the fuel injector power supply circuit.
9	Turn the ignition switch off. Disconnect the PCM connector. Measure the resistance between the suspected fuel injector terminal B and the following terminals of the connector: • For No.1 cylinder: 2B • For No.2 cylinder: 2C • For No.3 cylinder: 2D • For No.4 cylinder: 2H Is resistance less than 5.0 ohms?	Yes	Inspect the suspected fuel injector for the following: • Resistance • Fuel injection volume
9		No	Repair the fuel injector control circuit.
10	Is the air cleaner element free of restrictions?	Yes	Go to the next step.
10	Is the air cleaner element free of restrictions?	No	Replace air cleaner element.
11	Carry out a spark test. Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
11		No	Repair or replace the malfunctioning parts.
12	Carry out the fuel line pressure inspection. Is the fuel line pressure correct?	Yes	Go to the next step.
12		No	Zero or low: Inspect the fuel pump circuit. Inspect for fuel leakage inside the pressure regulator. Inspect for a clogged main fuel line. High: Inspect the pressure regulator for the high pressure cause. Inspect for a clogged fuel return line. Inspect the vacuum hose to pressure regulator.
13	Inspect the following PIDs: • ECT • O2S11 (When engine can be started) • MAF Are all the PIDs normal?	Yes	Go to the next step.
13		No	Repair or replace the malfunctioning parts.
14	Carry out the purge control inspection. (When engine can be started) Is the purge control correct?	Yes	Go to the next step.
14		No	Repair or replace the malfunctioning parts.
15	Carry out the compression inspection. Is compression correct?	Yes	Inspect for deformed in exhaust system.
15		No	Repair or replace the malfunctioning parts.
16	When the engine cannot be started, inspect the intake-air system for air leakage. When the engine can be started, carry out intake manifold vacuum inspection. Is air sucked in from the intake-air system?	Yes	Repair or replace the malfunctioning part.
16		No	Go to the next step.
17	Carry out the fuel line pressure inspection. Is the fuel line pressure correct?	Yes	Inspect the following PIDs. • ECT • O2S11 • MAF Inspect PCM ground condition.
17		No	Zero or low: Inspect for a clogged fuel line. If normal, replace the fuel pump unit. High: Replace the fuel pump unit.
18	Verify the test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect related Service information and perform repair or diagnosis. - If the vehicle is repaired, the troubleshooting is completed. - If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.