No.28 Spark Plug Condition - Mazda 6 2002 Workshop Manual

NO.28 SPARK PLUG CONDITION

28 SPARK PLUG CONDITION
DESCRIPTION Incorrect spark plug condition
Note
• Inspecting spark plugs condition can determine whether problem is related to a specific cylinder
Wet/carbon stuck on specific plug:
• Spark—Weak, not visible
• Air/fuel miture—Ecessive fuel injection volume
• Compression—No compression, low compression
• Faulty spark plug
Grayish white with specific plug:
• Air/fuel miture—Insufficient fuel injection volume
• Faulty spark plug
Wet/carbon is stuck on all plugs:
• Spark—Spark weak
• Air/fuel miture—Too rich
• Compression—Low compression
• Clogging in intake/ehaust system
Grayish white with all plugs:
POSSIBLE CAUSE
• Air/fuel miture—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
• • • • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or
Caution
• • • • Disconnecting/connecting quick release connector without cleaning it may possibly cause
Diagnostic procedure
STEP INSPECTION
1 Remove all spark plugs.
Inspect spark plug condition.
Is spark plug condition okay?
2 Is spark plug wet/covered with carbon by engine
oil?
3 Inspect spark plug for following:
• Cracked insulator
• Heat range
• Air gap
• Worn electrode
Is spark plug okay?
4 Inspect compression pressure at suspected
faulty cylinder.
Is compression pressure correct?
(See B–9 COMPRESSION
5 Install all spark plugs.
Carry out spark test at suspected faulty cylinder.
Is strong blue spark visible?
(Compare with normal cylinder.)
TROUBLESHOOTING
possibly all cylinders.
keep sparks and flames away from fuel.
death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete
“BEFORE REPAIR PROCEDURE” and “AFTER REPAIR PROCEDURE” described in this
manual.
(See F–17 BEFORE REPAIR
(See F–17 AFTER REPAIR
damage to fuel pipe and quick release connector. Always clean quick release connector
joint area before disconnecting/connecting, and make sure that it is free of foreign material.
INSPECTION.)
PROCEDURE.)
PROCEDURE.)
RESULTS
Yes Troubleshooting completed.
No Specific plug is wet or covered with carbon:
Go to net 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.
Yes Working up and down inspect all areas related to oil.
No Go to net step.
Yes Go to net step.
No Replace spark plug.
Yes Go to net step.
No Repair or replace malfunctioning parts.
Yes Go to net step.
No Repair or replace malfunctioning parts.
A6E398018881W30
ACTION
F–225
F