Misfire Detection Monitoring

Misfire Detection Monitor is an on-board strategy designed to monitor engine misfire and identify a specific cylinder in which misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. Misfire Detection Monitor will be enabled only when certain base engine conditions are first satisfied. Input from ECT or CHT, MAF and CKP sensors is required to enable the monitor. Misfire Detection Monitor is also performed during KOEO and KOER self-test. The following occurs during Misfire Detection Monitor:

PCM synchronized ignition spark is based on information received from CKP sensor. CKP signal generated is also main input used in determining cylinder misfire.
Input signal generated by CKP sensor is derived by sensing the passing of teeth from crankshaft position wheel mounted on end of crankshaft.
Input signal to PCM is then used to calculate time between CKP edges and also crankshaft rotational velocity and acceleration. By comparing accelerations of each cylinder event, power loss of each cylinder is determined. When power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then suspect cylinder is determined to have misfired.
Misfire types are as follows:
1. Misfire Type A
  
  Upon detection of a Misfire Type A (200 revolutions) which would cause catalyst damage, MIL will blink once per second during actual misfire, and a DTC will be stored.
2. Misfire Type B
  
  Upon detection of a Misfire Type B (1000 revolutions) which will exceed emissions threshold or cause a vehicle to fail an inspection and maintenance tailpipe emissions test, MIL will illuminate and a DTC will be stored.
The DTC associated with multiple cylinder misfire for a Type A or Type B misfire is DTC P0300. DTCs associated with an individual cylinder misfire for a Type A or Type B misfire are; DTCs P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0309 and P0310.