printable version

Multi-point fuel injection (MFI)

A multipoint fuel injection (MFI) consists of sensors which determine the state of the engine, the engine control module (ECM) that controls the actuators based on information from the sensors. The engine control module (ECM) controls the injectors for direct injection of fuel, the air supply when the engine is idling and adjusts ignition timing. In addition, the engine control unit (ECM) has several diagnostic functions that facilitate troubleshooting.

Fuel injector

Torque control and the opening time of the fuel injectors is carried out so as to maintain an optimum air-fuel ratio at all operating conditions of the engine. At the inlet of each cylinder is set one fuel injector. Fuel from a fuel tank is supplied under pressure created by the fuel pump and an adjustable pressure regulator. Thus, stable fuel distributed to each fuel injector. Fuel injection nozzle is carried out once every two revolutions of the crankshaft, in the sequence of cylinders 1-3-4-2. The engine control module ECM enriches the fuel mixture, working on the "open loop" at warming up the engine and high duty cycle. In addition, when a hot engine operation at normal loads the engine control unit ECM controls toplivnovozdushnoy mixture ratio based on signals from the heated oxygen sensor in the "closed cycle" to ensure the normal operation of the three-way catalytic converter.

Management of engine speed to idle

The engine speed at idling is maintained at an optimum level of additional supply air flowing into the bypass throttle valve in accordance with changes in conditions and engine load. The engine control unit ECM controls the engine speed at idling (ISC), maintaining the predetermined frequency, depending on the coolant temperature and the load on the air conditioning system. Furthermore, when the air conditioning switch is turned off while the engine is running at idling speed is regulated by supplying additional air to bypass the throttle valve, in order to avoid oscillations in the engine speed.

Management of the ignition timing

Switch power located in the low voltage circuit of the ignition system controls the opening and closing current flowing in the primary winding of the ignition coil.

The switch controls the ignition timing to provide optimum ignition timing at all operating conditions of the engine. Setting the ignition timing determined by the engine control unit ECM depending on the rotational speed, the volume of incoming air, coolant temperature and atmospheric pressure.

Additional management features

1. The fuel pump control.

Includes fuel pump relay so that the current supplied to the fuel pump at startup and during operation of the engine.

2. Management of compressor clutch relay.

It turns the compressor clutch.

3. Management of the radiator fan relay.

Rotation frequency radiator and condenser fan are controlled in dependence on the coolant temperature and the vehicle speed.

4. Management EVAP.

Diagnostic mode

• When a fault is detected in one of the sensors or actuators connected to the engine control as a warning to the driver turns the control lamp CHECK ENGINE / MALFUNCTION INDICATOR.
• When a fault is detected in one of the sensors or actuators, will be recorded in the memory of the DTC.
• DTC in the ECM, which is linked with the sensors and actuators can be read by a special device.

Simulation test traffic

If simulation test pull, fold, twist and pull the wiring of each of the sensors to determine the location of an intermittent malfunction.

• Shake the connector up and down and left and right.
• Shake harness up and down and left and right.
• Create some element or vibration sensor.

Inspection Service at the fuse

Remove fuse and measure the resistance between the load side of the blown fuse, and "weight". Turn on all the switches located in the electrical circuit. If the resistance is zero, then there is a short circuit between these switches and the load. If the resistance is zero, it means that there is no short circuit, and the fuse blows as a result of short-term excess current.

The main reasons for short circuit.

• Harness clamping elements of the car body.
• Damage to the outer casing harness resulting abrasion or heat.
• Water trapped in the connector or circuitry
• Individual error.