L-Jetronic fuel injection system
On BMW car engines «525i», «528i», «528iA» And «535i» Bosch L-Jetronic electronically controlled intermittent fuel injection system was used.
The principle of operation of the fuel injection system
An electric fuel pump takes fuel from the tank and delivers it at a pressure of about 2.5 kg / cm2 through a fine filter to a distribution line connected by hoses to each engine cylinder. Installed at the end of the distribution line, the fuel pressure regulator maintains a constant injection pressure and drains excess fuel into the tank, i.e. it circulates the fuel in the system and eliminates the formation of fuel vapors in it.
The amount of injected fuel is determined by the electronic control unit depending on the volume and temperature of the incoming air, the engine speed and engine load, as well as the temperature of the coolant. The main parameter that determines the dosage of fuel is the volume of intake air measured by the air flow meter. The incoming air flow deflects the pressure throttle valve, overcoming the force of the spring and shifts it to a certain angle, which is converted into electrical voltage by means of a potentiometer. The corresponding electrical signal is transmitted to the control unit, which determines the required amount of fuel at the current moment of engine operation and issues fuel supply time pulses to the solenoid valves of the injectors. Regardless of the position of the intake valves, the injectors simultaneously inject fuel twice for every revolution of the camshaft. If the intake valve is closed, fuel is collected in the space ahead of the valve and is sucked into the cylinder the next time it is opened, along with air.
An additional air supply valve installed in the air duct, made parallel to the throttle valve, brings additional air to the engine during cold start and engine warm-up, which leads to an increase in the engine idle speed.
To facilitate starting a cold engine, an electromagnetic starting nozzle is provided, the opening time of which varies depending on the temperature of the coolant by a thermal time relay.
Adjustment Data
The frequency of rotation of the crankshaft of the engine at idle, rpm 900±50.
Carbon monoxide content (SO) in exhaust gases, not more than, %: 0.5-2.0.
The L-Jetronic fuel injection system consists of the following main elements:
- Bosch pressure regulator 0 280 160 0141);
- Bosch electronic control unit 0 280 001 1082) installed in the glove box;
- coolant temperature sensor Bosch 0 280 130 023;
- Bosch thermal time relay 0 280 130 2193);
- Bosch air flow meter 0 280 203 0024) (normal air consumption at a pressure of 980 mbar and a temperature of 20°C, mm3 / h: 550);
- air temperature sensor;
- Bosch throttle switch 0 280 120 2065);
- two additional resistors;
- solenoid injection nozzles Bosch 0 280 150 1526) (injection start pressure, kg/cm2: 2.0-3.0);
- electromagnetic starting nozzle Bosch 0 280 170 032 (working pressure, kg/cm2: 2.0-3.0);
- vacuum limiter;
- electric fuel pump Bosch 0 580 464 013;
- relay.
1) 0 280 160 213 for BMW «5251/E28» And «5281/E28».
2) 0 280 001 114 for BMW «535i».
3) 0 280 001 300 on «525i/E28» And «528i/E28», 0 280 130 214 for BMW «535i» and from model year 1980 on «525i» And «528i».
4) 0 280 202 015 for BMW «525i/E28» And «528i/E28».
5) 0 280 120 302 for BMW «525i/E28» And «5281/E28» (permissible contact opening angle: 90°, full load contact opening angle: 60°).
6) 0 280 150 203 for BMW «525i/E28» And «5281/E28».