Air Fuel Ratio Imbalance Monitor - Torque Monitor
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- The air fuel ratio imbalance torque monitor is supplemented by the air fuel ratio imbalance monitor HO2S monitor. The air fuel ratio imbalance monitor torque monitor is used to detect small levels of cylinder to cylinder air fuel ratio imbalance.
- The monitor uses the crankshaft position sensor (CKP) to calculate an acceleration term during each cylinder firing event. The calculated acceleration value is proportional to engine torque during the firing event. The monitor will modulate each cylinder to generate an air fuel ratio deviation relative to stoichiometric operation. The monitor generates five total torque values for each cylinder. Two torque values richer than stoichiometric, two torque values leaner than stoichiometric and one torque value at stoichiometric. The monitor uses a calibrated torque curve defined by the five generated values compared to an ideal torque curve to estimate each cylinder air fuel ratio deviation. The monitor estimates each cylinder air fuel ratio deviation compared to the other cylinders to determine if a concern exists.
- The malfunction indicator lamp (MIL) is activated after a concern is detected during a drive cycle.