2014 Mazda 3 SV, Automatic TransFACTORY OEM SERVICE PROCEDURE

No. 28 Spark Plug Condition: Notes

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

28  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 .)
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    When to See a Mechanic

    Stop DIY work and contact a certified mechanic immediately if any of the following apply:

    • • You smell fuel, burning insulation, or see smoke.
    • • Brakes feel soft, pull hard to one side, or make grinding noises.
    • • The engine overheats, stalls repeatedly, or misfires under load.
    • • You are missing required tools, torque specs, or safe lifting equipment.
    • • You are not confident in the next step or safety outcome.