Engine Control System
PGM-FI SystemThe Programmed Fuel Injection (PGM-FI) system is a sequential multiport fuel injection system.
TDC (Top Dead Center) Sensor
The TDC1/TDC2 sensor determines ignition timing at start up (cranking) and when crank angle is abnormal.
CKP (Cylinder Position) Sensor
The CKP sensor determines timing for fuel injection of each cylinder and also detects engine speed.
Primary and Secondary HO2S (Heated Oxygen sensors)
The heated oxygen sensors detect the oxygen content in the exhaust gas and send signals to the PCM which varies the duration of fuel injection accordingly. To stabilize its output, the sensor has an internal heater. The primary sensor is installed in the exhaust pipe.
The secondary HO2S, installed in the TWC, detects the oxygen content in the exhaust gas downstream of the TWC and sends signals to the ECM/PCM, which varies the duration of fuel injection accordingly. To stabilize it's output, the sensor has an internal heater.
By controlling the air/fuel ratio with primary and secondary HO2 sensors, the deterioration of the primary sensor can be evaluated by its feedback period. When the feedback period exceeds a certain value during stable driving conditions, the sensor is considered deteriorated and the ECM/PCM sets a DTC.