NO.28 SPARK PLUG CONDITION [L3]


28	SPARK PLUG CONDITION
DESCRIPTION	Incorrect spark plug condition
POSSIBLE CAUSE	Note • Inspecting spark plugs condition can determine whether problem is related to a specific cylinder 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 • Faulty spark plug Grayish white with specific plug: • Air/fuel mixture-Insufficient fuel injection volume • Faulty 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 "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual. (See BEFORE SERVICE PRECAUTION [L3].) (See AFTER SERVICE PRECAUTION [L3].) Caution • Disconnecting/connecting quick release connector without cleaning it may possibly cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.


STEP	INSPECTION	RESULTS	ACTION
1	Remove all spark plugs. Inspect the spark plug condition. Is the spark plug condition 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 9. All plugs look grayish white: Go to Step 15.
2	Is the spark plug wet/covered with carbon by engine oil?	Yes	Working up and down inspect all areas related to oil.
2	Is the spark plug wet/covered with carbon by engine oil?	No	Go to the next step.
3	Inspect 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 the malfunctioning cylinder. Is the compression pressure correct? (See COMPRESSION INSPECTION [L3].)	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning part.
5	Install all spark plugs. Perform the spark test at the malfunctioning cylinder. Is strong blue spark visible? (Compare with normal cylinder.)	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning part.
6	Perform the fuel line pressure inspection. (See FUEL LINE PRESSURE INSPECTION [L3].) Is 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 fuel pump circuit. Inspect for fuel pump relief valve open. Inspect for fuel leakage inside the pressure regulator. Inspect for clogged main fuel line. High: Inspect the pressure regulator for high pressure cause. Inspect for clogged fuel return line.
7	Inspect the spark plug for following. • Heat range • Air gap Is the spark plug normal?	Yes	Go to the next step.
7		No	Replace the spark plug.
8	Remove the fuel injector. Inspect the following: • Resistance (See FUEL INJECTOR INSPECTION [L3].) • Fuel injection volume (See FUEL INJECTOR INSPECTION [L3].) Are all above items normal?	Yes	Inspect for open circuit between the fuel injector connector terminal and the following PCM connector terminals: • For #1 or #4 cylinder: 1A • For #2 or #3 cylinder: 1B
8		No	Replace fuel injector.
9	Is the air cleaner element free of restrictions?	Yes	Go to the next step.
9	Is the air cleaner element free of restrictions?	No	Replace the air cleaner element.
10	Perform the spark test. Is strong blue spark visible at each cylinder?	Yes	Go to the next step.
10		No	Repair or replace the malfunctioning part.
11	Perform the fuel line pressure inspection. (See FUEL LINE PRESSURE INSPECTION [L3].) Is fuel line pressure correct?	Yes	Go to the next step.
11		No	Zero or low: Inspect for the clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].)
12	Inspect the following PIDs. • ECT • O2S11 (When engine can be started) • MAF (See PCM INSPECTION [L3].) Are PIDs normal?	Yes	Go to the next step.
12		No	Repair or replace the malfunctioning part.
13	Perform the purge control inspection. (When engine can be started) (See Purge Control System Inspection.) Is the purge control correct?	Yes	Go to the next step.
13		No	Repair or replace the malfunctioning part.
14	Perform the compression inspection. Is the compression correct?	Yes	Inspect for clogging in the exhaust system.
14		No	Repair or replace the malfunctioning part.
15	When the engine cannot be started, inspect the intake-air system for air leakage. When the engine can be started, perform the intake manifold vacuum inspection. Is air sucked in from the intake-air system?	Yes	Repair or replace the malfunctioning part.
15		No	Go to the next step.
16	Perform the fuel line pressure inspection. (See FUEL LINE PRESSURE INSPECTION [L3].) Is fuel line pressure correct?	Yes	Inspect the following PIDs. • ECT • O2S11 • MAF (See PCM INSPECTION [L3].) Inspect PCM GND condition.
16		No	Zero or low: Inspect for the clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].)
17	Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace or reprogram PCM.