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

id0103a7804500

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
•  Malfunctioning spark plug
Grayish white with specific plug:
•  Air/fuel mixture—Insufficient fuel injection volume
•  Malfunctioning 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.

Diagnostic procedure

STEP

INSPECTION

ACTION
1
•  Remove all spark plugs.
•  Inspect the spark plug condition.
•  Is the spark plug condition normal?
Yes
Troubleshooting completed.
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.
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.
No
Replace the spark plug.
4
•  Inspect the compression pressure at suspected malfunction cylinder.
•  Is the compression pressure correct?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
5
•  Install all spark plugs.
•  Carry out spark test at suspected malfunction cylinder.
•  Is the strong blue spark visible? (Compare with normal cylinder.)
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts.
6
•  Carry out the fuel pressure inspection.
•  Is the fuel line pressure correct?
Yes
Inspect the fuel injector for the following:
•  Open or short in fuel injector
•  Leakage
•  Injection volume
No
Zero or low:
Inspect the clogged fuel line.
•  If the normal, replace the fuel pump unit.
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)
7
•  Inspect the spark plug for the following.
―  Heat range
―  Air gap
•  Is the spark plug normal?
Yes
Go to the next step.
No
Replace the spark plug.
8
•  Remove the suspected fuel injector.
•  Inspect the following:
―  Resistance
―  Fuel injection volume
•  Are all above items normal?
Yes
Inspect for open circuit between the suspected fuel injector connector terminal and the PCM connector terminals.
No
Replace the fuel injector.
9
•  Is the air cleaner element free of restriction?
Yes
Go to the next step.
No
Replace the air cleaner element.
10
•  Carry out spark test.
•  Is the strong blue spark visible at each cylinder?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
11
•  Carry out the fuel pressure inspection.
•  Is the fuel line pressure correct?
Yes
Go to the next step.
No
Zero or low:
Inspect the clogged fuel line.
•  If the normal, replace the fuel pump unit.
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)
12
•  Inspect the following PIDs.
―  ECT
―  O2S11
―  O2S21
―  MAF
―  O2S12
―  O2S22
•  Are PIDs normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
13
•  Carry out purge control inspection (when engine can be started).
•  Is the purge control correct?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
14
•  Carry out compression inspection.
•  Is the compression correct?
Yes
Inspect for clogging in exhaust system.
No
Repair or replace the 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 the air sucked in from intake-air system?
Yes
Repair or replace the malfunctioning part.
No
Go to the next step.
16
•  Carry out the fuel pressure inspection.
•  Is the fuel line pressure correct?
Yes
Inspect the following PIDs.
•  ECT
•  O2S11
•  O2S21
•  MAF
•  O2S12
•  O2S22
Inspect the PCM ground condition.
No
Zero or low:
Inspect the clogged fuel line.
•  If normal, replace the fuel pump unit.
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)
17
•  Verify the test results.
―  If normal, return to the 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 the PCM.