Mazda 6 2002 - No.8 Engine Runs Rough;Rolling Idle

TROUBLESHOOTING
F199
F
NO.8 ENGINE RUNS ROUGH/ROLLING IDLE
A6E398018881W10
Diagnostic procedure
8 ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION
• Engine speed fluctuates between specified idle speed and lower speed and engine shakes
excessively.
• Idle speed is too slow and engine shakes excessively.
POSSIBLE CAUSE
• 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
• 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
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 REPAIR PROCEDURE and AFTER REPAIR PROCEDURE described in this
manual.
(See F17 BEFORE REPAIR PROCEDURE.)
(See F17 AFTER REPAIR PROCEDURE.)
Caution
•
••
• Disconnecting/connecting quick release connector without cleaning it may possibly cause
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.
STEP INSPECTION RESULTS ACTION
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?
Yes Go to next step.
No Service as necessary.
Repeat Step 1.