Preliminary Inspection

Before performing any symptom tests, perform DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article and verify that all of the following are true before using the symptom diagnosis:

• The Powertrain Control Module (PCM) and the Malfunction Indicator Lamp (MIL) are operating correctly.
• No DTCs are stored.
• The scan tool data is within a normal operating range.
• Verify customer complaint and locate the correct symptom. See SYMPTOM DIAGNOSIS  . Check the items indicated under that symptom.

Several of the symptom procedures call for a careful visual/physical check. DO NOT neglect to perform the visual/physical check. The visual/physical check is an important procedure that can lead to the correction of a concern without further diagnosis. The performance of the visual/physical check can save valuable time. The visual/physical check should include the following:

• Inspect all the PCM grounds for secure and clean connections that are in the proper location.
• Check all vacuum hoses for splits, kinks, and proper connections, as shown on the Vehicle Emission Control Information label.
• Check the vacuum hoses thoroughly for any type of leak or restriction. Inspect the air inlet ducts for collapsed or restricted sections.
• Check for air leaks at throttle body mounting area and intake manifold sealing surfaces.
• Inspect the wiring harness for proper connections and damage.