Mazda 626 - Emission Compliance

TROUBLESHOOTING
NO.14 EMISSION COMPLIANCE
14
Emission compliance
DESCRIPTION
• Emission compliance test is failed.
POSSIBLE
CAUSE
• Vacuum lines leakage or blockage
• Cooling system malfunction
• Spark plug malfunction
• Leakage from intake manifold
• Erratic or no signal from CMP sensor
• Inadequate fuel pressure
• PCV valve malfunction or incorrect valve installation
• EGR valve malfunction
• Exhaust system clogging
• Fuel tank ventilation system malfunction
• Charcoal canister damage
• Excessive carbon buildup in combustion chamber
• Improper engine compression
• Improper valve timing
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 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”. (See
Section F)
Caution
• Disconnecting/connecting the quick release connector without cleaning It may possibly
cause damage to the fuel pipe and quick release connector. Always clean the quick
release connector joint area before disconnecting/connecting, and make sure that it is
free of foreign material.
Diagnostic Procedure
STEP INSPECTION
RESULTS
ACTION
1 Inspect following:
• Vacuum lines for leakage or blockage
• Electrical connections
• Proper maintenance schedule followed
• Intake-air system and air cleaner element
concerns: obstructions, leakage or dirt
Are all items okay?
Yes
Go to next step.
No Service as necessary.
Repeat Step 1.
2
Connect NGS tester to DLC.
Turn ignition switch on.
Retrieve any DTC.
Is any DTC displayed?
Yes DTC is displayed:
Go to appropriate DTC test.
No No DTC Is displayed:
Go to next step.
3 Is any other drivability concern present? Yes Go to appropriate symptom troubleshooting.
No
Go to next step.
4
Connect NGS tester to DLC.
Access ECT PID.
Warm up engine and run it at idle.
Is ECT PID correct?
Yes
Go to next step.
No Inspect for coolant leakage, cooling fan and
condenser fan operation or thermostat
operation.
F1-131