Circuit Description

The Crankshaft Position (CKP) sensor sends pulses to ECM as the reluctor wheel rotate past the sensor. A misfire will cause an unexpected change in crankshaft speed. ECM continuously calculates crankshaft position from CKP sensor signals. This information is used to determine which cylinder is misfiring so that ECM can increment the appropriate misfire counter and sets the appropriate DTC. If ECM is unable to determine that a specific cylinder is misfiring or if misfire is random and on multiple cylinders, DTC P0300 will set.

DTC will set when a misfire have been detected after a series of tests when:

• Engine speed between 520-6520 RPM.
• Traction control is not active.
• Engine running for greater than 5 seconds.
• IAT greater than 17°F (-8°C).
• EVAP diagnosis is not active.
• No TP or CKP DTCs set.