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NO.30 SPARK PLUG CONDITION [AJ]

BME010300103235

30 | 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].)
  (See AFTER SERVICE PRECAUTION [AJ].)

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 the malfunctioning cylinder. • Is the compression pressure correct? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part.
5 | • Install all spark plugs. • Perform the spark test at the malfunctioning cylinder. • Is strong blue spark visible? (Compare with the normal cylinder.) | Yes | Go to the next step.
No | Repair or replace the malfunctioning parts.
6 | • Perform the fuel line pressure inspection. (See PRESSURE REGULATOR INSPECTION [AJ].) • Is 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 fuel pump circuit. • Inspect for open fuel pump relief valve. • Inspect for fuel leakage inside the pressure regulator. • Inspect for clogged main fuel line. High:
• Inspect the pressure regulator for pressure cause.
• Inspect for clogged fuel return line.
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 fuel injector. • Inspect the following:

  - Resistance
  (See FUEL INJECTOR INSPECTION [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
  - Fuel injection volume
  (See FUEL INJECTOR INSPECTION [AJ] (VIN: JM0 LW10J300 301406-, JMZ LW69J7*# 307683-, JM8 LW28J**# 301514-, JM8 LW28A**# 301514- (Assumed)).)

• Are all above items normal?
Yes
Inspect for open circuit between the fuel injector connector terminal and 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 | • Perform the spark test. • Is strong blue spark visible at each cylinder? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part.
11 | • Carry out fuel line pressure inspection. • Is fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ].) | Yes | Go to the next step.
No | Zero or low: • Inspect fuel pump circuit. • Inspect for open fuel pump relief valve. • 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.
12 | • Inspect the following PIDs.

  - ECT
  - O2S11
  - O2S21
  - MAF
  - O2S12
  - O2S22
  (See PCM Inspection Using the WDS or Equivalent.)
  (See PCM Inspection Using the SST (WDS or equivalent).)

• Are 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). • Is the purge control correct? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part.
14 | • Perform the compression inspection. • Is the compression correct? | Yes | Inspect for clogging in the exhaust system.
No | Repair or replace the malfunctioning part.
15 | • When the engine cannot be started, inspect the intake-air system for air leakage. • When the engine can be started, perform the 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.
16 | • Perform the fuel line pressure inspection. • Is fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ].) | Yes | Inspect the following PIDs. • ECT • O2S11 • O2S21 • MAF
• O2S12
• O2S22
(See PCM Inspection Using the WDS or Equivalent.)
(See PCM Inspection Using the SST (WDS or equivalent).)
Inspect PCM GND condition.
No | Zero or low: • Inspect fuel pump circuit. • Inspect for open fuel pump relief valve. • Inspect for fuel leakage inside the pressure regulator. • Inspect for clogged main fuel line. High:
• Inspect the pressure regulator for high pressure cause.
• Inspect for clogged fuel return line.
17 | • Verify test results.

  - If normal, 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 or reprogram the PCM.