Electronic Engine Controls
The engine management system provides optimum control of the engine under all operating conditions using several strategically placed sensors and any necessary actuators. Electronic engine control consists of:
engine control module
throttle position sensor
engine coolant temperature sensor
camshaft position sensor
crankshaft position sensor
mass air flow sensor
intake air temperature sensor
knock sensor
heated oxygen sensor
Engine Control Module (ECM)
The ECM incorporates a comprehensive monitoring and diagnostic capability including software variations to ensure system compliance with the latest diagnostic and emissions legislation in different markets. The engine control module controls the coil on plug ignition system, electronic fuel system, cruise control and the electronic throttle control system.
The ECM responds to input signals received from sensors relating to engine operating conditions and provides output signals to the appropriate actuators. These output signals are based on the evaluated input signals which are compared with calibrated data tables or maps held within the ECM before the output signal is generated.
The ECM needs the following inputs to calibrate the engine properly:
camshaft position
engine rpm
engine coolant temperature
amount of engine detonation
Throttle Position (TP) Sensor
- sends the ECM a signal indicating throttle plate angle
- is the main input to the ECM from the driver
- is a dual Hall effect device mounted on the motor end of the throttle body
Two additional sensors are attached to the throttle body to provide additional feedback to the ECM a mechanical guard position sensor and an accelerator pedal position sensor.
Camshaft Position (CMP) Sensor
- sends the ECM a signal indicating camshaft position for fuel synchronization purposes
- is a variable reluctance device mounted on bank 2 cylinder side face
- generates a signal when the ring fitted to the bank 2 inlet camshaft passes the sensor
Crankshaft Position (CKP) Sensor
- is a variable reluctance device mounted on the engine oil pan
- generates a signal when the drive plate passes the sensor
- sends the ECM signals indicating crankshaft position and engine speed
- is essential for calculating spark timing
Engine Coolant Temperature (ECT) Sensor
- sends the ECM a signal indicating the temperature of the engine coolant
- is a temperature dependent resistor with a negative temperature coefficient (resistance changes inversely with respect to temperature) and is constantly monitored by the ECM
Intake Air Temperature (IAT) Sensor
- is mounted in the same housing as the MAF sensor but is not a serviceable item
- sends the ECM a signal indicating the temperature of the air entering the engine
- is a temperature dependent resistor which has a negative temperature coefficient (its resistance
- changes inversely with respect to ambient temperature).
Knock Sensor (KS)
- is a piezo-electric device which sends a signal to the ECM indicating engine detonation
Between 700 and 6800 rpm, the ECM will retard individual cylinder ignition timing when detonation occurs while allowing the other cylinders to continue operating normally.
During acceleration, at critical load and speed conditions, the ECM retards ignition timing to prevent the onset of detonation.
Heated Oxygen Sensor (HO2S)
- are positioned upstream of the catalytic convertor
- is equipped with a heating element which improves the response time of the sensors during engine warm-up
- has the ability to generate a voltage signal proportional to the oxygen content of the exhaust gases leaving the engine
- provides feedback information to the ECM used to calculate fuel delivery and provide optimum gas emissions
Oxygen Sensor (O2S)
- are positioned downstream of the catalytic convertor
- has the ability to generate a voltage signal proportional to the oxygen content of the exhaust gases leaving the catalytic convertor
- provides feedback information to the ECM used to calculate fuel delivery
Mass Air Flow (MAF) Sensor
Location:
- is of the 'hot-wire' type (the resistance of the wire varies as incoming air passing over it has a cooling effect)
- provides feedback to the ECM to permit monitoring of mass air flow
- is NOT serviceable, necessitating its renewal should a fault occur