NO.28 SPARK PLUG CONDITION [L3]

BME010300000W30

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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.
(See BEFORE REPAIR PROCEDURE [L3].)
(See AFTER REPAIR PROCEDURE [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.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Remove all spark plugs.
Inspect spark plug condition.
Is spark plug condition okay?
Yes
Troubleshooting completed.
No

Specific plug is wet or covered with carbon:

Go to 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.
No
Go to next step.
3
Inspect spark plug for following:
• Cracked insulator
• Heat range
• Air gap
• Worn electrode
Is spark plug okay?
Yes
Go to next step.
No
Replace spark plug.
4
Inspect compression pressure at suspected faulty cylinder.
Is compression pressure correct?
Yes
Go to next step.
No
Repair or replace malfunctioning parts.
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 next step.
No
Repair or replace malfunctioning parts.
6
Carry out fuel line pressure inspection.
Is fuel line pressure correct?
Yes
Inspect fuel injector for following:
• Open or short in injector
• Leakage
• Injection volume
No

Zero or low:

Inspect fuel pump circuit.
Inspect for fuel pump relief valve open.
Inspect for fuel leakage inside pressure regulator.
Inspect for clogged main fuel line.

High:

Inspect pressure regulator for high pressure cause.
Inspect for clogged fuel return line.
7
Inspect spark plug for following.
• Heat range
• Air gap
Is spark plug okay?
Yes
Go to next step.
No
Replace spark plug.
8
Remove suspected fuel injector.
Inspect following:
• Resistance
• Fuel injection volume
Are all above items okay?
Yes
Inspect for open circuit between suspected fuel injector connector terminal and PCM connector following terminals:

• For #1 or #4 cylinder: 1A

• For #2 or #3 cylinder: 1B

No
Replace fuel injector.
9
Is air cleaner element free of restrictions?
Yes
Go to next step.
No
Replace air cleaner element.
10
Carry out spark test.
Is strong blue spark visible at each cylinder?
Yes
Go to next step.
No
Repair or replace malfunctioning parts.
11
Carry out fuel line pressure inspection.
Is fuel line pressure correct?
Yes
Go to next step.
No

Zero or low:

Inspect for clogged fuel line.
If okay, replace fuel pump unit.

High:

Replace fuel pump unit.
12
Inspect following PIDs.
• ECT
• O2S11 (When engine can be started)
• MAF
Are PIDs okay?
Yes
Go to next step.
No
Repair or replace malfunctioning parts.
13
Carry out purge control inspection.
(When engine can be started)
Is purge control correct?
Yes
Go to next step.
No
Repair or replace malfunctioning parts.
14
Carry out compression inspection.
Is compression correct?
Yes
Inspect for clogging in exhaust system.
No
Repair or replace malfunctioning parts.
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.
No
Go to next step.
16
Carry out fuel line pressure inspection.
Is fuel line pressure correct?
Yes
Inspect following PIDs.
• ECT
• O2S11
• MAF
(See PCM INSPECTION [L3].)
Inspect PCM GND condition.
No

Zero or low:

Inspect for clogged fuel line.
If okay, replace fuel pump unit.

High:

Replace fuel pump unit.
17
Verify test results.
• If okay, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace or reprogram PCM.