1 - injection valve (injector)
2 - cold start valve
3 - dispenser (distributor) fuel
4 - electromagnetic pressure control device
5 - fuel pressure regulator
6 - mixture regulator
7 - mixture adjustment screw
8 - back-up valve
9 - idle speed controller
10 - throttle valve extreme position switch
11 - thermal time switch
12 - temperature sensor
13 - electronic control device
14 - fuel pressure accumulator
15 - fuel filter
16 - Electric fuel pump
17 - gas tank
KE-Jetronic is a mechanical petrol injection system with electronic control. The main mechanical system ensures sufficient reliability of the system in case of electronic failure.
Fuel is sucked from the fuel tank by an electric fuel pump and fed through a pressure accumulator and a fuel filter to the fuel distributor. Air is sucked by the engine through the intake manifold. Its quantity is measured by an air quantity meter. The fuel distributor distributes a certain quantity of fuel to individual cylinders through injection valves in accordance with the quantity of air. Additional sensors ensure the correct dosage of fuel in extreme engine operating situations.
To reduce fuel consumption, the injection system, except for 90 hp engines, has a device to stop its supply. The device works in such a way that when the driver releases the gas pedal, the fuel supply to the injection valves is automatically stopped. The termination of this device is determined by the engine speed and its temperature.
The fuel pressure accumulator maintains pressure in the system for a long time, even after the engine is turned off. This prevents the formation of vapor locks and improves the hot start mode.
The diaphragm fuel pressure regulator maintains the system pressure at 564 bar.
The electrohydraulic actuator is located on the fuel distributor and controls the fuel flow depending on the operating condition of the engine. Its task is to enrich the mixture during cold start and engine warm-up. In addition, the actuator closes the fuel supply in the forced idle mode at engine speeds above 1400 rpm.
The idle speed controller regulates the air intake at idle speed bypassing the throttle valve. This ensures that the same idle speed is achieved regardless of whether the brake booster or the air conditioning compressor is on or off. The idle speed controller is controlled by the electronic injection unit KE.
The exhaust gas lambda probe is installed before the catalytic converter. It measures the residual oxygen content in the exhaust gases and transmits a corresponding voltage signal to the KE control unit. Accordingly, the control unit regulates the fuel-air ratio so that they can be burned in the catalytic converter. To ensure that the sensor reaches its operating temperature (over +300°C) as quickly as possible and to maintain it constant thereafter, it has an electric heater.
Caution: When working with the injection system, special cleanliness must be observed. Before disassembling, the parts must be washed with gasoline. The system is under high pressure. Therefore, before disassembling the system, it is necessary to relieve the pressure by opening the cold start valve.
Caution: In this case, the connection must first be covered with a rag. There is a risk of injury from a jet of high-pressure fuel! Remove any leaking fuel with a rag.
Caution: When the ignition is on and the engine is running, do not remove the plug from the KE control unit, as the unit may be damaged due to the current peak.
Caution: Observe safety precautions when working with the electronic ignition system.
(This article was previously published on the resource AUDIMANUAL.ru)