Mazda CX-9 Grand Touring 2009 Manual page 1382

If malfunction remains, inspect related Service Bulletins and/or On-line Repair
Information and perform repair or diagnosis.
3
NO.29 SPARK PLUG CONDITION [MZI-3.7]
NO.29 SPARK PLUG CONDITION (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES
29 SPARK PLUG CONDITION
DESCRIPTION Incorrect spark plug condition
NOTE:
Wet/carbon stuck on specific plug:
Grayish white with specific plug:
POSSIBLE
CAUSE
Wet/carbon is stuck on all plugs:
Grayish white with all plugs:
2008 Mazda CX-9 Grand Touring
2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9
If vehicle is repaired, troubleshooting completed.
If vehicle is not repaired or additional diagnostic information is not available,
replace the PCM.
(See PCM REMOVAL/INSTALLATION [MZI-3.7] .)
Inspecting spark plugs condition can determine whether problem is related
to a specific cylinder or possibly all cylinders.
Spark-Weak, not visible
Air/fuel mixture-Excessive fuel injection volume
Compression-No compression, low compression
Malfunction spark plug
Air/fuel mixture-Insufficient fuel injection volume
Malfunction spark plug
Spark-Spark weak
Air/fuel mixture-Too rich
Compression-Low compression
Clogging in intake/exhaust system
Air/fuel mixture-Too lean
WARNING:
The following troubleshooting flow chart contains the fuel system diagnosis