The Bosch injection system provides electronic control of the high-pressure fuel pump and injection timing, and also controls the operation of the exhaust gas recirculation (EGR) system and glow plugs.
The system is controlled by an electronic control unit (ECU), which receives signals from sensors monitoring engine load, engine speed, injector operation and coolant temperature. The ECU determines the injection timing of the fuel pump and the operation of the EGR solenoid valve via the accelerator cable and vacuum diaphragm.
The Lucas EPIC injection system provides programmed electronic control of the high pressure fuel pump and electronic control of the exhaust gas recirculation system via the Electronic Control Unit (ECU).
The system is controlled by the ECU control unit from the accelerator pedal position sensor, intake manifold vacuum sensor, engine speed sensor, crankshaft position sensor, coolant temperature sensor and intake air temperature sensor. The EGR valve operation is also controlled by the ECU in combination with the solenoid valve.
The unique feature of this system is the accelerator control. Instead of an accelerator cable connected to a high-pressure pump, the accelerator pedal is connected to a pedal position sensor. This sensor sends pedal position signals to the ECU, which in turn electronically controls the high-pressure fuel pump.
The fuel system includes:
- fuel tank mounted at the rear of a vehicle;
- fuel filter with separator;
- electronically controlled high pressure fuel pump;
- injectors;
- binding components.
Before the fuel passes through the filter, the fuel is heated by coolant passing through the base of the fuel filter. A turbocharger and cooler are installed on all models.
Fuel from the fuel tank is supplied to the high-pressure fuel pump by a centrifugal pump located in the high-pressure fuel pump. A fuel filter is installed in front of the fuel pump, where the fuel is cleaned of foreign particles and water. Excess fuel lubricates the fuel pump and returns to the fuel tank through a pipeline.
The high pressure fuel pump rotates at half the speed of the crankshaft and is driven by a toothed belt from the crankshaft.
The amount of fuel supplied is controlled by a centrifugal regulator, which responds to the position of the accelerator pedal and the engine speed. The regulator is connected to a metering valve, which increases or decreases the amount of fuel supplied during each pump cycle.
The fuel injection timing is determined by the pump. When the engine is running, the fuel injection timing is changed automatically in the pump by the ECU system.
Four fuel injectors spray fuel into swirl chambers located in the cylinder head. The injectors are calibrated to open and close at a precise pressure, ensuring efficient and complete combustion of the fuel. Each injector needle is lubricated with fuel, which accumulates in the space around the spring and then flows to the return hose.
Cold starting is facilitated by glow plugs installed in each swirl chamber. On the Bosch system, cold engine idle speed is increased by vacuum acting through a diaphragm on the accelerator cable. On the Lucas system, idle speed is automatically controlled by the fuel pump. Both systems are controlled by the ECU.
The electromagnetic engine stop valve shuts off the fuel supply to the fuel pump rotor when the ignition is switched off. The Bosch high-pressure fuel pump also has an engine stop lever.
A fuel pump with good maintenance can last longer than the engine before needing repair. The main cause of damage to the fuel pump and injectors is dirt or water in the fuel.
Servicing the fuel pump and injectors is very complex and should therefore be done at a Peugeot service station.
When working on the Lucas injection system, additional precautions must be taken:
- always disconnect the negative battery terminal before disconnecting any fuel system connections;
- when installing the battery, do not mix up the poles;
- do not expose system components (especially ECU) blows;
- do not open the ECU unit;
- prevent moisture from entering the electronic control system components (when washing the engine, protect the system from water ingress).