NO.27 SPARK PLUG CONDITION [WITHOUT WU-TWC]

id0103008044c6

27

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 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.
(See BEFORE REPAIR PROCEDURE.)
(See AFTER REPAIR PROCEDURE.)
Caution
• If there is foreign material on the connecting area of the quick release connector, it might damage the connector or fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Remove all spark plugs.
Inspect the spark plugs.
Are the spark plugs 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 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.
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 the malfunctioning cylinder.
Is the compression pressure correct?
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts.
5
Install all spark plugs.
Carry out a spark test at the suspected the malfunctioning cylinder.
Is a strong blue spark visible?
(See Spark Test.)
(Compare with normal cylinder.)
Yes
Go to the next step.
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
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 cause of the high pressure.
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.
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.
No
Repair the open or short 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 PCM 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
No
Repair the fuel injector control circuit.
10
Is the air cleaner element free of restrictions?
Yes
Go to the next step.
No
Replace the air cleaner element.
11
Carry out a spark test.
Is a strong blue spark visible at each cylinder?
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts.
12
Carry out fuel line pressure inspection.
Is the fuel line pressure correct?
Yes
Go to the next step.
No

Zero or low:

Inspect the fuel pump circuit.
Inspect for fuel leakage inside the pressure regulator.
Inspect for clogged main fuel line.

High:

Inspect the pressure regulator for the cause of high pressure.
Inspect for 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.
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.
No
Repair or replace the malfunctioning parts.
15
Carry out the compression inspection.
Is compression correct?
Yes
Inspect for clogging in the exhaust system.
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.
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
(See PCM INSPECTION [WITHOUT WU-TWC].)
Inspect the PCM ground condition.
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 test results.
• If normal, return to the diagnostic index to service any additional symptoms.
• If the malfunction remains, replace or reprogram the PCM.