The fuel injection system is virtually maintenance free. The need for repair is extremely rare. If the sensors fail, the control unit switches to work according to the emergency program. At the same time, the corresponding signal lamp lights up on the front panel. In this case, the engine may work unstably, which affects the quality of the movement of the car. The resulting system malfunctions are recorded in the memory of the on-board computer. Some of them can be retrieved from memory by fairly simple methods. Troubleshooting the fuel injection system requires special knowledge, measuring instruments and tools. Therefore, it is recommended that such work be carried out in a specialized TOYOTA workshop.
The EFI injection system is an electronically controlled fuel injection system in which injection is carried out, depending on the operating state of the engine, into the engine intake pipe just before the intake valves.
Fuel is sucked from the tank by an electric fuel pump and fed through the fuel filter to the fuel line, and then to the injection valves. The rail pressure regulator ensures that the fuel pressure is kept constant, depending on the air pressure in the intake pipe. The intake air is cleaned by the air filter and fed through the suction pipe to the engine.
Vacuum in the suction pipe depends on throttle starvation (gas pedal position) and engine speed.
The vacuum in the suction pipe is determined by the sensor and, together with the engine speed, is the initial information for the control unit in the amount of air taken in by the engine. The intake air vacuum sensor is located on the bulkhead separating the engine compartment from the passenger compartment and is connected by a vacuum tube to the suction pipe. The engine speed is determined by the Hall sensor located in the ignition distributor.
Ignition control unit and injection system (ECU) Depending on the air flow and the speed, it determines the duration of the fuel injection and, therefore, the quantity according to the optimal characteristics contained in the control unit vapors. A longer injection valve opening time injects more fuel per revolution of the crankshaft. The control unit is located in the vehicle interior in a housing behind the center console.
Additional sensors and elements of the injection system are used to determine the correct ratio of air and fuel in the mixture.
The throttle valve potentiometer is located directly on the valve shaft and provides the control unit with information about the position of the throttle valve. With its help, in particular, the fuel supply to the engine is stopped in the forced idling mode, when the idling contact of the limit switch is closed and at the same time the engine speed is above a certain value.
idle speed controller (solenoid valve) controls the air supply bypassing the throttle valve. Thus, the number of revolutions of the engine is stabilized during its warm-up period.
Oxygen sensor (Lambda probe) measures the oxygen content in the exhaust gases and transmits the corresponding signal in the form of voltage to the control unit. Based on this, the control unit changes the ratio of the components of the fuel-air mixture in such a way that optimal afterburning of the exhaust gases in the catalyst is ensured.
The temperature sensor measures the intake air temperature. The second temperature sensor measures the coolant temperature at the cylinder head.
A valve is installed at the vent hole of the fuel tank, which is controlled depending on the operating state of the engine. Fuel vapors in the tank are accumulated in an activated carbon filter and are discharged through a special valve to the combustion chambers of the engine. This increases the efficiency of the engine and eliminates the ingress of harmful fumes into the atmosphere.
Attention: When working on the fuel injection system, compliance with cleanliness requirements.