K-Jetronic fuel injection system
On car models «230» And «280» installed a mechanical fuel injection system «K-Jetronic» Bosch company.
The principle of operation of the fuel injection system
The fuel pump takes fuel from the fuel tank and delivers it to the accumulator, where the fuel pressure in the system is maintained within the range of 4.5–5.2 kg/cm2. Fuel through the filter is supplied under pressure to the fuel dispenser.
The pressure disk of the air mass meter fixed on the movable lever, which is installed between the air filter and the throttle valve, deviates depending on the air depression in the engine. The displacement of the pressure disk of the air flow meter is transmitted to the distribution plunger of the fuel dispenser-distributor, thereby determining the amount of fuel supplied. The fuel quantity distributor, depending on the position of the pressure plate of the air flow meter, continuously supplies the required amount of fuel to the engine cylinders through the injectors, ensuring the optimal composition of the fuel-air mixture. The fuel dispenser and air flow meter form a mixture regulator.
The pilot pressure regulator reduces pressure on the control plunger during engine warm-up. Reducing the control pressure at the same air flow leads to an increase in the fuel supply and, consequently, to an enrichment of the combustible mixture.
An additional air supply valve installed in the air duct, made parallel to the throttle valve, brings additional air to the engine during engine start-up and 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 is regulated depending on the temperature of the coolant by a thermal time switch.
Adjustment Data
Characteristic | Meaning |
Fuel pressure in the system, kg/cm2 | 4,5—5,2 |
Control pressure on a warm engine, kg/cm2 | 2,7—3,1 |
Control pressure when the warm engine is idling, kg/cm2 | 3,4—3,8 |
Pilot pressure on a cold engine depending on the coolant temperature (see Checking the injection system), kg/cm2 | 0,5—2,0 |
Residual fuel pressure in the system, not less than, kg/cm2 | 1,7 |
Frequency of rotation of a cranked shaft idling, rpm | 900±50 |
Carbon monoxide content (SO) in exhaust gases, % | |
| 1,1 |
| < 3,0 |
Fuel pump
Electric multisection fuel pump.
Characteristic | Meaning |
Brand and part number | Bosch 0 580 254 982 |
Fuel supply pressure, kg/cm2 | 5,5 |
Pump capacity, l/h | 100 |
Pump performance when tested on a car with a 1/2 filled fuel tank for 30 s, cm3 | 750 |
Operating voltage, V | 7—15 |
Consumed current, no more, A | 4,7 |
Fuel filter
Characteristic | Meaning |
brand | Purolator |
Type: | |
| GF 140/1 |
| GF 140/1 |
| GF 148 |
Brand and part number Bosch | 0 438 060 043 |
Fuel storage
Characteristic | Meaning |
Brand and part number («230») | Bosch 0 580 254 982 |
Chamber volume, cm3 («280») | 20 |
Residual pressure, kg/cm2 | |
| 1,7—2,4 |
| 5,0 |
Mixture regulator
Characteristic | Meaning |
Brand and part number | |
| Bosch 0 438 040 088 and 0 438 060 025 |
| Bosch 0 438 040 009 and 0 438 060 043 |
Air flow meter
Characteristic | Meaning |
Brand and part number | Bosch 0 438 120 158 and 0 438 120 086 |
Color index | yellow-violet |
Fuel dispenser
Characteristic | Meaning |
Brand and part number | Bosch 0 438 100 108 |
Injection nozzles
Characteristic | Meaning |
Brand and part number | |
| Bosch 0 437 502 006 |
| Bosch 0 437 502 007 EP/LKE 7 |
Injection start pressure, kg/cm2 | 2,7—3,8 |
Fuel cone angle («280») | 35° |
Electromagnetic starting nozzle
Characteristic | Meaning |
Brand and part number | |
| Bosch 0 280 170 410 |
| Bosch 0 280 170 405 and 0 280 170 411 |
Rated voltage, V | 12 |
Working pressure, kg/cm2 | |
| 4,5 |
| –4,5 |
Operating voltage, V | 7—15 |
Power consumption, W | 37 |
Fuel cone angle («280») | 80° |
Volume of injected fuel, cm3 /min | 95—135 |
Thermal time switch
Characteristic | Meaning |
Brand and part number | Bosch 0 280 130 214 and 0 280 130 220 |
Rated voltage, V | 12 |
Contact opening temperature,°C | +35 |
Duration of switching on, no more than, s | 8 |
Cold start relay
Characteristic | Meaning |
Brand and part number | Bosch 0 332 003 028 |
Pilot pressure regulator
Characteristic | Meaning |
Brand and part number | Bosch 0 438 140 005 |
Rated voltage, V | 12 |
Maximum allowable voltage (briefly), IN | 20 |
Operating voltage, V | 7—15 |
Auxiliary air valve
Characteristic | Meaning |
Brand and part number | |
| Bosch 0 280 140 134 |
| Bosch 0 280 140 100 |
Minimum voltage, V | 12 |
Maximum allowable voltage (briefly), IN | 20 |
Operating voltage, V | 7—15 |
L-Jetronic fuel injection system
On car engines «280E» Bosch L-Jetronic electronically controlled intermittent fuel injection system was used.
The principle of operation of the fuel injection system
An electric fuel pump draws 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 disc, 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 switch.
The L-Jetronic fuel injection system consists of the following main elements:
- Bosch pressure regulator, catalog nos. 0 280 160 014, 0 280 160 213;
- Bosch electronic control unit, catalog numbers 0 280 001 108, 0 280 001 300;
- Bosch coolant temperature sensor, catalog number 0 280 130 023;
- Bosch thermal time switch, catalog nos. 0 280 130 219, 0 280 130 214;
- Bosch air flow meter, catalog nos. 0 280 203 002, 0 280 202 015 (normal air consumption at a pressure of 980 mbar and a temperature of 20°C, mm3 / h: 550);
- air temperature sensor;
- Bosch throttle switch, catalog nos. 0 280 120 206, 0 280 120 302 (admissible angle of opening of contact of idling: 90°; full load contact opening angle: 60°);
- two additional resistors;
- Bosch solenoid injection nozzles, catalog nos. 0 280 150 152, 0 280 150 203 (injection start pressure, kg/cm2: 2.0—3.0);
- Bosch solenoid starter, catalog no. 0 280 170 032 (working pressure, kg/cm2: 2.0—3.0);
- oxygen concentration sensor in the exhaust gas;
- Bosch electric fuel pump, catalog number 0 580 464 013;
- relay.
Adjustment Data
Characteristic | Meaning |
Engine crankshaft idling speed, rpm | 900±50 |
Carbon monoxide content (SO) in exhaust gases, not more than, % | 0,5—2,0 |
Tightening torques of the main threaded connections, kgf·m
Connection type | Meaning |
The union of the pipeline of a supply of fuel, carving M 14x1,5 (the greatest residual moment on the body), no more | 1,5 |
Fuel drain fitting, thread M 12x1.5 | 3,0 |
coolant temperature sensor | 1,5 |
Thermal time relay, no more | 3,0 |
nozzles (on the inlet pipe), thread M 6x16 | 0,9—1,1 |