Initial Inspection and Diagnostic Overview

1. Verify the customer concern by running the engine at 2000 rpm or by road testing the vehicle.
2. Visually inspect the components of the exhaust system and related controls that may affect exhaust gas quality or cause a backfire or a loss of power.
3. Visually inspect for obvious signs of mechanical and electrical damage; refer to the following list:

Mechanical
- Leaking fuel injector tips
- Damaged air inlet passages
- Inoperative exhaust gas recirculation (EGR) valve
- Exhaust pipe pinched, crushed
- Damaged, loose vacuum hoses
- Incorrect idle speed
- Dirty engine air cleaner
- Damaged catalytic converter

Electrical
- Misrouted,damaged wing
- Damaged, loose connectors
- Damaged ignition system

4. Inspect the wiring and connectors of the components for obvious problems due to looseness, corrosion or other damage. This must be done while the engine is fully warmed and the system controls are activated.
5. Check the vacuum lines and connections for looseness, pinching, leakage, splitting, blockage or other damage.
6. If a vacuum line or orifice (restricter) blockage is suspected, correct the cause before proceeding to the next step.
7. If the concern is not visually evident, determine the symptom and proceed to the Symptom Chart.