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

Location:

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

Variable Valve Timing (VVT) Solenoid
Refer to 'Variable Valve Timing Solenoid.'

Mass Air Flow (MAF) Sensor:

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