Preliminary Inspection

• Verify on-vehicle diagnostics are working by performing appropriate ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
• Ensure PCM grounds are clean, tight, and properly located.
• Check vacuum hoses for splits, kinks, leaks, restrictions and proper connections. Ensure vacuum hoses are correctly routed as shown on vehicle emission control information label.
• Check for air leaks at all intake manifold sealing surfaces.
• Check ignition wires for cracking, hardness, proper routing and carbon tracking.
• Check wiring for proper connections and routing, pinches, burns, cuts or other damage.
• Ensure PCM and MIL are functioning properly.
• Ensure there are no DTCs stored, or only intermittent DTCs are present.
• Ensure fuel control system is operating properly. See appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Perform fuel system pressure test. See appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Perform a careful visual inspection of all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. Not all items listed under each symptom apply to all models and systems. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. See appropriate SYSTEM & COMPONENT TESTING article for test procedures.