NO.27 SPARK PLUG CONDITION [L8, LF, L5]

id010346804400

27

SPARK PLUG CONDITION
DESCRIPTION
Incorrect spark plug condition
POSSIBLE CAUSE
Note
•  Inspecting the spark plug conditions can determine whether a 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
•  Malfunction spark plug
Grayish white with specific plug:
•  Air/fuel mixture—Insufficient fuel injection volume
•  Malfunction 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 servicing the fuel system:
•  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.
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION
1
Remove all the spark plugs.
Inspect the spark plug condition.
Are the spark plugs conditions 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
Are the spark plugs wet/covered with carbon from the engine oil?
Yes
Inspect all areas related to oil, working up and down.
No
Go to the next step.
3
Inspect the spark plugs for the following:
•  Cracked insulator
•  Heat range
•  Air gap
•  Worn electrode
Are the spark plugs normal?
Yes
Go to the next step.
No
Replace the spark plug.
(See SPARK PLUG REMOVAL/INSTALLATION [L8, LF, L5].)
4
Inspect the compression pressure at the suspected malfunctioning cylinder.
Is the compression pressure correct?
(See COMPRESSION INSPECTION [L8, LF, L5].)
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
5
Install all the spark plugs.
Perform the spark test at the suspected malfunctioning cylinder.
Is a strong blue spark visible?
(Compare with normal cylinder.)
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
6
Inspect the fuel line pressure.
(See FUEL LINE PRESSURE INSPECTION [L8, LF, L5].)
Is the fuel line pressure correct?
Yes
Inspect fuel injector for the following:
•  Open or short circuit in injector
•  Leakage
•  Injection volume
No
Zero or low:
Inspect the fuel pump relay and fuel pump circuit.
Inspect the fuel line for clogging.
If there is no malfunction, replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
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.
(See SPARK PLUG REMOVAL/INSTALLATION [L8, LF, L5].)
8
Remove the suspected fuel injector.
Inspect the following:
•  Resistance
•  Fuel injection volume
Are all the above items normal?
Yes
Inspect for an open circuit in the wiring harness between fuel injector connector terminal A and the PCM at the following terminals:
•  For No.1 cylinder: 2BB
•  For No.2 cylinder: 2BC
•  For No.3 cylinder: 2BD
•  For No.4 cylinder: 2AZ
No
Replace the fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION [L8, LF, L5].)
9
Is the air cleaner element free of clogging?
Yes
Go to the next step.
No
Replace the air cleaner element.
10
Perform the spark test.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)
Is a strong blue spark visible at each cylinder?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
11
Inspect the fuel line pressure.
(See FUEL LINE PRESSURE INSPECTION [L8, LF, L5].)
Is the fuel line pressure correct?
Yes
Go to the next step.
No
Zero or low:
Inspect the fuel pump relay and fuel pump circuit.
Inspect the fuel line for clogging.
If there is no malfunction, replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
12
Inspect the following PIDs:
•  ECT
•  O2S11 (When engine can be started.)
•  O2S12 (When engine can be started.)
•  MAF
(See PCM INSPECTION [L8, LF, L5].)
Are the PIDs normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
13
Perform the purge control inspection.
(When engine can be started.)
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)
Is the purge control correct?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
14
Perform the compression inspection.
(See COMPRESSION INSPECTION [L8, LF, L5].)
Is the compression correct?
Yes
Visually inspect for deformed exhaust system parts.
No
Repair or replace the malfunctioning part.
15
If the engine cannot be started, inspect the intake air system for air leakage.
If the engine can be started, perform the intake manifold vacuum inspection.
Is air sucked in from intake air system?
Yes
Repair or replace the malfunctioning part.
No
Go to the next step.
16
Inspect the fuel line pressure.
(See FUEL LINE PRESSURE INSPECTION [L8, LF, L5].)
Is the fuel line pressure correct?
Yes
Inspect the following PIDs:
•  ECT
•  O2S11
•  O2S12
•  MAF
(See PCM INSPECTION [L8, LF, L5].)
Inspect PCM ground condition.
No
Zero or low:
Inspect the fuel pump relay and fuel pump circuit.
Inspect the fuel line for clogging.
If there is no malfunction, replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
17
•  Verify test results.
―  If normal, return to the diagnostic index to service any additional symptoms.
―  If the malfunction remains, inspect the related Service Information and perform repair or diagnosis.
•  If the vehicle is repaired, troubleshooting is completed.
•  If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.