Engine Management System Actuators

System Actuators

In response to signals received from the sensors, the engine ECM controls and directs messages to a series of electronic and electro-mechanical actuators. The function and location of the actuators is given below.

  • Throttle actuator motor- situated within the throttle body. The throttle actuator motor opens and closes the throttle plates in the throttle body, in response to commands from the engine ECM. The throttle actuator motor is an integral part of the throttle body.

  • Canister purge valve - situated in the vapour return line between the carbon canister and the throttle body. The purge valve controls the return of vapour which has been stored in the carbon canister during the period when the engine is switched off. The valve is 'pulsed' by the engine ECM to give control over the rate at which the canister is purged.

  • Fuel Injectors - located in the fuel rail. The engine is fitted with three injectors. The spray pattern of the injectors is fixed but the length of time each injector can remain open is variable according to operating conditions. The duration of each injection is calculated by the engine ECM using data received from the various sensors in the system.

  • Ignition coils - plug-top coils are located in the camshaft cover. There are three coils fitted, one for each spark plug. The engine ECM controls the point at which the coils are switched on and off. In calculating the switch-on time, the engine ECM allows sufficient time for the coils to charge to a level where a spark can be produced. The coils are switched off at the point of ignition, the timing of which is optimised for good engine performance.

  • Engine Management System (EMS) main relay - situated under the seat. When the ignition is switched on, the EMS main relay is powered up to provide a stable Voltage supply for the engine ECM. When the ignition is turned off, the engine ECM carries out a power down sequence during which the EMS main relay remains powered by the engine ECM for one minute. The engine ECM power down sequence includes: writing the adaption data to engine ECM memory.

  • Fuel pump - located inside the fuel tank. The electric pump delivers fuel into the fuel system, via a pressure regulator, at a constant 3.5 bar pressure. The pump is run continuously when the engine is operating and is also run briefly when the ignition is first switched on to ensure that 3.5 bar is available to the system as soon as the engine is cranked. Fuel pressure is controlled by a regulator also situated inside the fuel tank.

  • Cooling fan - located behind the radiator. The engine ECM controls switching on and off of the cooling fan in response to a signal received from the coolant temperature sensor. When the coolant temperature rises to a level where the cooling effect of natural airflow is insufficient, the cooling fan is turned on by the engine ECM. When the coolant temperature falls sufficiently, the engine ECM turns the cooling fan off. The fan only becomes operational when the engine is running. It will not operate at any other time.

  • Secondary air injection solenoid - located above the camshaft cover. The secondary air injection solenoid controls airflow through the secondary air injection system.

note
In this system, the starter lockout system (clutch switch, gear position sensor, side stand switch) all operate through the engine ECM.