Symptom Related Diagnostic Procedures

NOTES:
- Determine if any Diagnostic Trouble Codes (DTC) are stored in the Engine Control Module (ECM), (Especially if the vehicle does not start). Correct any faults indicated before proceding.

- 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. Ignition coils for proper connection at the sparkplugs.
3. Wiring harnesses for proper routing and connection.

SYMPTOMS:
Hard Start/No Start
Check:
1. For any stored DTCs.
2. Battery and Starter Condition
3. For Fuel Quantity and Quality
4. Fuel Filter for Clogging or Restrictions
5. Fuel Injector Operation
6. Ignition Spark

Rough Idle
Check:
1. Exhaust Gas Recirculation (EGR) System
2. Positive Crankcase Ventilation (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. Mass Air Flow Sensor

Fails Emission Test
Check:
1. Catalytic Converters
2. Evaporative Emission Controls
3. EGR System
4. Mass Air Flow Sensor
5. Heated Oxygen Sensor

Loss Of Power
Check:
1. Catalytic Converters
2. EGR System
3. Throttle Body
4. Fuel Supply System
5. Throttle Position Sensor
6. Mass Air Flow Sensor