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No. 28 Spark Plug Condition: Contents

28 SPARK PLUG CONDITION
DESCRIPTION
  • Incorrect spark plug condition.
TROUBLE AREA HINT: 
  • 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, excessive fuel line pressure
  • Erratic signal to ECM
    • ECT sensor No. 1 or related circuit malfunction
    • MAF sensor or related circuit malfunction
    • A/F sensor or related circuit malfunction
    • HO2S or related circuit malfunction
  • Compression-Low compression
  • Restriction in intake/exhaust system

Grayish white with all plugs: 
  • Erratic signal to ECM
    • ECT sensor No. 1 or related circuit malfunction
    • MAF sensor or related circuit malfunction
    • A/F sensor or related circuit malfunction
    • HO2S or related circuit malfunction
  • Air/fuel mixture-Too lean, insufficient fuel line pressure
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 information.

      Refer to PRECAUTION [07/2015 - ]

      Refer to ON-VEHICLE INSPECTION [07/2015 - ]

NOTE:
  • 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 matter.
NOTE:
  • Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.
RELATED PIDS

Item (definition) Unit/Condition Definition Condition/Specification (Reference)
Engine coolant temperature °C, °F Engine coolant temperature
  • Displays ECT
V ECT sensor No. 1 voltage Ignition switched ON (engine off)
  • ECT is 29°C {84°F}: Approx. 2.65 V
  • ECT is 88°C {190°F}: Approx. 0.71 V
Mass Air Flow gm/sec Mass air flow
  • Displays MAF
V MAF sensor voltage
  • Ignition switched ON (engine off) (MAF: 0.59 g/s {0.078 lb/min}): Approx. 0.72 V
  • Idle (after warm up) (MAF: 2.17 g/s {0.287 lb/min}): Approx. 0.97 V
  • Racing (engine speed is 2000 RPM) (MAF: 4.73 g/s {0.626 lb/min}): Approx. 1.26 V
Heated Exhaust Gas Oxygen Sensor (bank 1, sensor 1) μA A/F sensor current
  • Idle (after warm up): Approx. 0-50 μA
  • Deceleration fuel cut (accelerator pedal released from engine speed of 4000 RPM or more): Approx. 3.84 mA
Heated Exhaust Gas Oxygen Sensor (bank 1, sensor 2) V HO2S voltage
  • Idle (after warm up): 0-1.0 V
  • Deceleration fuel cut (accelerator pedal released from engine speed of 4000 RPM or more): Approx. 0 V
Engine Revolutions Per Minute RPM Engine speed
  • Displays engine speed
Vehicle Speed km/h Vehicle speed
  • Displays vehicle speed
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