Symptom Related Diagnostic Procedures

NOTE: If the vehicle exhibits any of the following symptoms and an emission component is suspect, be sure to visually inspect the following before any tests are performed:
1. Vacuum hoses for leaks, splits, kinks and proper routing.
2. Ignitions wires for cracking, hardness and proper connection at the distributor and sparkplugs.
3. Wiring harnesses for proper routing and connection.

Determine if any fault codes are stored in the Engine Control Module (ECM). Correct any faults indicated before proceding.

SYMPTOM:

ROUGH IDLE
Check:
1. EGR System
2. PCV System
3. Hoses and Connections
4. Idle Air Control Valve

FREQUENT STALLING, WARM ENGINE
Check:
1. EGR System
2. Fuel Pressure Regulator
3. Fuel injector
4. Idle Air Control Valve

ROUGH RUNNING OR MISFIRE
Check:
1. EGR System
2. PCV System
3. Fuel Injector
4. Fuel Pressure Regulator
5. Throttle Position Sensor
6. Manifold Absolute Pressure Sensor

FAILS EMISSION TEST
Check:
1. Catalytic Converter
2. Evaporative Emission Controls
3. EGR System
4. Manifold Absolute Pressure Sensor
5. Heated Oxygen Sensor

LOSS OF POWER
Check:
1. Catalytic Converter
2. EGR System
3. Throttle Body
4. Fuel Supply System
5. Variable Valve Timing Solenoid and Pressure Switches
6. Throttle Position Sensor
7. Manifold Absolute Pressure Sensor