No. 28 Spark Plug Condition: Notes

WARNING: This page is about a different car, the 2014 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

NO. 28 SPARK PLUG CONDITION DESCRIPTION AND POSSIBLE CAUSES (SKYACTIV-G 2.0, SKYACTIV-G 2.5)

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, excessive fuel line pressure
Erratic signal to PCM
- 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 PCM
- 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 manual. (See BEFORE SERVICE PRECAUTION .) (See AFTER SERVICE PRECAUTION .)
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 matter.

CAUTION:

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)
ECT	°C,°F	Engine coolant temperature	Displays ECT
ECT	V	ECT sensor No. 1 voltage	ECT is 20 °C {68 °F}: Approx. 3.10 V ECT is 40 °C {104 °F}: Approx. 2.16 V ECT is 60 °C {140 °F}: Approx. 1.40 V ECT is 80 °C {176 °F}: Approx. 0.87 V ECT is 100 °C {212 °F}: Approx. 0.54 V
MAF	g/Sec	Mass airflow	Displays MAF
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. 0.86 V Racing (engine speed is 2, 000 rpm) (MAF: 4.73 g/s {0.626 lb/min}): Approx. 1.07 V
O2S11	μA	A/F sensor current	Idle (after warm up): Approx. -39 μA Deceleration fuel cut (accelerator pedal released from engine speed of 4, 000 rpm or more): Approx. 3.84 mA
O2S12	V	HO2S voltage	Idle (after warm up): 0-1.0 V Deceleration fuel cut (accelerator pedal released from engine speed of 4, 000 rpm or more): Approx. 0 V
RPM	RPM	Engine speed	Displays engine speed
VSS	KPH, MPH	Vehicle speed	Displays vehicle speed.