Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
3
HARD START/LONG CRANK/ERRATIC START/ERRATIC CRANK
DESCRIPTION
• Starter cranks engine at normal speed but engine requires excessive cranking time before start
• Battery in normal condition
POSSIBLE
CAUSE
• Spark leak from hightension leads
• Poor fuel quality
• Spark plug malfunction
• Erratic signal from crankshaft position sensor
• Positive crankcase ventilation (PCV) valve malfunction
• Purge solenoid valve malfunction
• Restriction in exhaust system
• Vacuum leaks
• Starting system malfunction
• Air leak from intake air system
• Air cleaner restriction
• Inadequate fuel pressure
• Mass air flow sensor contamination
• EGR valve malfunction
Warning
Following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read
following warnings before performing fuel system service:
• 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 leaks 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
REPAIR PROCEDURE” and “AFTER REPAIR PROCEDURE” described in this manual.
cr 0 1 -1 4 BEFORE REPAIR PROCEDURE
o- 0 1 -1 4 AFTER REPAIR PROCEDURE
STEP
INSPECTION ACTION
1
Verify following:
• Vacuum leaks
• Fuel quality (i.e. proper octane,
contamination, winter/summer blend).
• Loose bands on intake air system.
• Cracks on intake air system parts.
• Air cleaner restriction.
Are all items okay?
Yes Go to next step.
No Service as necessary.
2
Are any DTCs displayed during continuous
memory, KOEO and KOER self-test? Yes
DTC displayed.
Go to appropriate DTC test.
No
No DTC displayed.
Go to next step.
3 Is engine overheating? Yes
Go to flowchart 17 for “COOLING SYSTEM CONCERNS
OVERHEATING”.
No Go to next step.
4 Check for cracks on high tension leads
is there any crack on high tension leads? Yes Repair suspected high tension lead.
No Go to next step.
5 Check spark plug conditions.
Is spark plug wet, converted with carbon or
grayish white?
Yes If spark plug is wet or converted with carbon, check for
fuel leak from fuel injector.
If spark plug is grayish white, check for clogged fuel
injector.
No Install spark plugs on original cylinders.
Go to next step.
6
Visually inspect crankshaft position (CKP)
sensor and teeth of crankshaft pulley.
Is CKP sensor and teeth of crankshaft pulley
okay?
Yes Go to next step.
No Replace malfunctioning part.
7
Measure gap between crankshaft position
(CKP) sensor and teeth of crankshaft pulley.
Specification
0.5— 1.5 mm {0.02—0.05 in}
Is gap within specification?
Yes Go to next step.
No
Adjust CKP sensor.
01-01A -1 29