The amount of fuel supplied to the fuel injectors is controlled by the engine control unit (ECU). The ECU receives signals from the crank angle sensor and the camshaft position sensor and provides fuel to the fuel injector in the engine's cylinder sequence, resulting in improved fuel economy and reduced exhaust emissions. The ECU controls the fuel injection system, ignition and emissions exhaust gases. All information supplied to the ECU is compared with pre-set values stored in the ECU memory and determines the required fuel injection period Information regarding engine speed comes from the crankshaft angle sensor. This is an inductive pulse generator that determines the passage of the ridges between the 36 holes located on the inside of the flywheel. As each ridge passes, a signal is induced near the sensor, which is used by the ECU to determine the crankshaft speed. There is no ridge between holes 35 and 36, and by the absence of a sensor signal, the ECU determines the position of the crankshaft.
The camshaft position sensor is located on the PTE, Zetec and Zetec-E engines in the cylinder head and is controlled by a boss on the camshaft. On Endura-E engines the sensor is located on the chain cover and is controlled by a rotor plate bolted to the camshaft sprocket. The camshaft position sensor works in the same way as the crankshaft angle sensor, generating a series of pulses that allows the ECU to determine the firing order of the cylinders and open the fuel injectors in the appropriate sequence.
The mass air flow sensor is a live wire. It sends out a constantly changing voltage signal corresponding to the mass of air flowing into the engine.
To determine the temperature of the engine, a sensor is used, which is a thermistor, i.e. a semiconductor whose electrical resistance decreases with increasing temperature. This signal is used to determine the optimum composition of the fuel mixture at a certain engine temperature. Information about the temperature of the incoming air is determined by the sensor, which is a thermistor with a negative temperature coefficient. This information is also used by the ECU to determine the optimum fuel mixture for a given air temperature.
The throttle position sensor is mounted on the end of the throttle shaft and supplies the ECU with a constantly changing signal corresponding to the throttle opening value.
Vehicle speed is determined by the speed sensor, which is installed on the gearbox speedometer drive. The sensor generates a series of pulses. corresponding to the speed of the vehicle, allowing the ECU to correct the amount of fuel supplied by the fuel injectors and also transmits information to the on-board computer and cruise control systems. If the vehicle is equipped with power steering, a fluid pressure sensor in the power steering system is used.
An oxygen sensor installed in the exhaust system provides constant feedback that allows the fuel mixture to be adjusted for normal operation of the catalyst. The air supply system consists of an air filter housing, a mass air flow sensor, an intake hose, tubes and a throttle body. The throttle valve, located inside the throttle body, is controlled by the driver from the accelerator pedal. When the throttle is opened, the amount of air passing through the system increases and the signal from the air flow sensor changes, causing the ECU to open each fuel injector for a longer time. As a result, the amount of fuel entering the engine increases. Idle speed and mixture quality are controlled by the ECU and cannot be adjusted manually. Checking the idle speed and the quality of the fuel mixture can only be carried out using special diagnostic equipment at the service station.
Attention. The fuel system is under pressure even after the engine has been switched off. Therefore, when performing any work on the fuel system, it is necessary to depressurize it and relieve pressure.
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