No.8 Engine Runs Rough/Rolling Idle - Mazda 2002 6 Workshop Manual

NO.8 ENGINE RUNS ROUGH/ROLLING IDLE

8 ENGINE RUNS ROUGH/ROLLING IDLE
• Engine speed fluctuates between specified idle speed and lower speed and engine shakes
DESCRIPTION excessively.
• Idle speed is too slow and engine shakes excessively.
• Air leakage from intake-air system parts
• A/C system operation is improper
• Spark leakage from high-tension leads
• Spark plug malfunction
• Purge solenoid valve malfunction
• IAC valve improper operation
• EGR valve malfunction
• Erratic or no signal from CMP sensor
• Low engine compression
• Improper valve timing
• Improper variable valve timing control system operation (L3-VE)
• Erratic signal from CKP sensor
• Poor fuel quality
• PCV valve malfunction
• Air cleaner restriction
• Restriction in exhaust system
• Disconnected electrical connectors
• Inadequate fuel pressure
• Fuel pump body mechanical malfunction
• Improper load signal input
• Fuel line restriction or clogging
• Improper fuel injection control operation
POSSIBLE CAUSE
• Fuel leakage from fuel injector
• Fuel injector clogging
• Engine overheating
• Vacuum leakage
• Pressure regurator malfunction
Warning
The following troubleshooting flow chart contains fuel system diagnosis and repair
procedures. Read 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 Verify following:
• External fuel shut off or accessory (kill
switch, alarm etc.)
• Fuel quality (e.g. proper octane,
contamination, winter/summer blend)
• No air leakage from intake-air system
• Proper sealing of intake manifold and
components attached to intake manifold:
EGR valve, IAC valve
• Ignition wiring
• Electrical connections
• Fuses
• Smooth operation of throttle valve
Are all items okay?
TROUBLESHOOTING
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.
PROCEDURE.)
PROCEDURE.)
RESULTS
Yes Go to next step.
No Service as necessary.
Repeat Step 1.
A6E398018881W10
ACTION
F–199
F