Diagnostic Aids

When diagnosing an intermittent problem, use scan tool to review failure record information. This data can be used to duplicate a problem. If an IC circuit, fuel injector or EGR DTC is active and a misfire is active, diagnose those problems first. Use scan tool to monitor active misfire counts. Spraying water on wires will find bad wire(s). The scan tool active misfire counts should pick up an intermittent misfire problem. Watch scan tool misfire counter. When a specific cylinder misfires under certain load, conditions may be duplicated in the shop. Use the following specifications to help in diagnosis:

• Injector Resistance - 11.8-12.6 ohms.
• Wire Resistance - 1500-15,000 ohms.
• Coil Pack Resistance - 6500-11,500 ohms (Tower-To-Tower).
• Spark Plug Gap - 0.040" (1.0 mm).
• Wire Position On Coil - 4-1-2-3.