NO.28 SPARK PLUG CONDITION [AJ (3.0L Duratec)]


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 or to all cylinders. Wet/carbon is 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 stuck on all plugs: • 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 [AJ (3.0L Duratec)].) (See AFTER SERVICE PRECAUTION [AJ (3.0L Duratec)].)


STEP	INSPECTION		ACTION
1	• Remove all spark plugs. • Inspect spark plug condition. • Is spark plug condition okay?	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 spark plug wet/covered with carbon by engine oil?	Yes	Working up and down inspect all areas related to oil.
2	• Is spark plug wet/covered with carbon by engine oil?	No	Go to the next step.
3	• Inspect spark plug for following. - Cracked insulator - Heat range - Air gap - Worn electrode • Is spark plug okay?	Yes	Go to the next step.
3		No	Replace spark plug.
4	• Inspect compression pressure at suspected faulty cylinder. • Is compression pressure correct?	Yes	Go to the next step.
4		No	Repair or replace malfunctioning part.
5	• Install all spark plugs. • Carry out spark test at suspected faulty cylinder. • Is strong blue spark visible? (Compare with normal cylinder.)	Yes	Go to the next step.
5		No	Repair or replace malfunctioning parts.
6	• Carry out the fuel pressure inspection. • Is the fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)	Yes	Inspect the fuel injector for following: • Open or short in fuel injector • Leakage • Injection volume
6		No	Zero or low: Inspect clogged fuel line. • If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
7	• Inspect spark plug for following. - Heat range - Air gap • Is spark plug okay?	Yes	Go to the next step.
7		No	Replace spark plug.
8	• Remove suspected fuel injector. • Inspect following: - Resistance (See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].) - Fuel injection volume (See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].) • Are all above items okay?	Yes	Inspect for open circuit between suspected fuel injector connector terminal and PCM connector terminals.
8		No	Replace fuel injector.
9	• Is air cleaner element free of restriction?	Yes	Go to the next step.
9	• Is air cleaner element free of restriction?	No	Replace air cleaner element.
10	• Carry out spark test. • Is strong blue spark visible at each cylinder?	Yes	Go to the next step.
10		No	Repair or replace malfunctioning part.
11	• Carry out the fuel pressure inspection. • Is the fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)	Yes	Go to the next step.
11		No	Zero or low: Inspect clogged fuel line. • If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
12	• Inspect following PIDs. - ECT - O2S11 - O2S21 - MAF - O2S12 - O2S22 • Are PIDs okay?	Yes	Go to the next step.
12		No	Repair or replace malfunctioning part.
13	• Carry out purge control inspection (when engine can be started). • Is purge control correct?	Yes	Go to the next step.
13		No	Repair or replace malfunctioning part.
14	• Carry out compression inspection. • Is compression correct?	Yes	Inspect for clogging in exhaust system.
14		No	Repair or replace malfunctioning part.
15	• When engine cannot be started, inspect intake-air system for air leakage. • When engine can be started, carry out intake manifold vacuum inspection. • Is air sucked in from intake-air system?	Yes	Repair or replace malfunctioning part.
15		No	Go to the next step.
16	• Carry out the fuel pressure inspection. • Is the fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)	Yes	Inspect following PIDs. • ECT • O2S11 • O2S21 • MAF • O2S12 • O2S22 Inspect PCM GND condition.
16		No	Zero or low: Inspect clogged fuel line. • If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
17	• Verify test results. - If okay, return to diagnostic index to service any additional symptoms. - If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace PCM.