Circuit Description

Crankshaft Position (CKP) sensor reluctor (4X) is located on side of engine block behind starter assembly. CKP sensor will send a pulse on every falling edge of 4X reluctor wheel. A misfire will cause a change in crankshaft speed. PCM times interval between each pulse and compares each new interval with previous one to determine when an excessive change in crankshaft speed has occurred. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes are more than expected amount, PCM will interpret this as a misfire. PCM continuously calculates crankshaft position from low and high resolution signals. This information is used to determine which cylinder is misfiring so that PCM can increment appropriate misfire counter. Conditions for setting DTC:

• DTCs P0101, P0102, P0103, P0107, P0108, P0117, P0118, P0121, P0122, P0123, P0125, P0335, P0336, P0341, P0342, P0343, P0500, P0502, P0503 or P1258 not set.
• Engine speed 450-3001 RPM.
• Ignition voltage 11-16 volts.
• ECT is 19-266°F (-7°C to 130°C).
• Fuel level greater than 10 percent.
• Throttle angle within one percent.
• ABS and traction control not active.
• Transmission not changing gears.
• AIR diagnostics not active.
• A/C clutch steady.
• PCM not in fuel shut-off or decel fuel cut-off mode.
• ABS signals not exceeding rough road thresholds.
• PCM determines that an emission-type misfire is present.
• PCM determines that a catalyst damaging misfire is present.