Cold Start Spark Timing Monitor Operation

Once the waiting period is complete, the monitor compares the average difference between desired and commanded spark to a calibrated threshold that is a function of the engine coolant temperature at start. If the difference exceeds the calibrated threshold, a DTC is set.

• DTC: P050B Cold start ignition timing performance
• Monitor execution: Once per driving cycle, during the first 15 seconds of a cold start
• Monitor sequence: None
• Monitoring duration: Data gathering occurs during the first 15 seconds of a cold start. The decision to set P050B is made 300 seconds after start. This delay gives time for other diagnostics (for example, misfire monitor) to determine if another DTC should set instead of P050B.