Control block
between incoming information (from different sensors) and fuel dosage (through injection valve), speaking clearly, there is a control unit. Its task is to calculate the right amount of fuel for various driving and load conditions and «instruct to do it» injection valve. In this case, the control unit refers to the characteristics of the engine - a database in the memory of which there are all conceivable situations of engine operation. In this database, the fuel quantities corresponding to them are also stored as electrical signals.
The control unit is located in the engine compartment, hidden at the bottom right under the water repellent.
Central injection module
The intake air flows through this housing, and here - by the injection valve - fuel is added, as before in the carburetor.
But the injection module also includes other components that, in general, have little to do with the carburetor. This is - along with the injection valve already mentioned - a pressure regulator, an idle mixture supply stepper motor and a throttle potentiometer.
Throttle valve
It is located in the injection valve module and regulates the amount of air that the engine must suck in. The extent to which the damper opens is determined by the driver by pressing the gas pedal. The pedal and throttle are connected by a cable.
Central injection Multec with ignition system.
1 - inductive pulse sensor;
2 - coolant temperature sensor;
3 - injection valve;
4 - throttle potentiometer;
5 - knock sensor;
6 - pressure sensor in the intake manifold;
7 - fuel tank ventilation valve;
8 - ignition module DIS;
9 - exhaust gas recirculation valve;
10 - lambda probe;
11 - stepper motor that controls the supply of the working mixture at idle
Injection valve
The injection valve is opened by an electromagnet. Depending on the signal from the control unit, fuel may or may not flow. In order to ensure optimum atomization of the fuel, it is injected under pressure in a conical jet towards the orifice above the throttle valve.
Pressure regulator
The fuel pump delivers gasoline under pressure to the pressure regulator. This ensures a constant fuel pressure of 0.75 bar at the injection valve. It does this by decreasing or increasing the amount of fuel flowing through the return hose to the fuel tank. The fuel supply remains largely constant.
Intake manifold pressure sensor
It is located on the back of the front wall. Its task is to accurately determine the reduced pressure in the intake manifold. The data, converted into electrical impulses, is transmitted to the control unit. Accordingly, the amount of injected fuel and the ignition timing are regulated.
Idler stepper motor
This is a small electric motor with a lead screw. Ahead on the screw is the valve ball. The stepper motor regulates the additional amount of air flowing through the bypass port past the throttle valve. The stepper motor has 256 settings and additionally provides idle speed control at all loads. It also provides a solution to the problem at the stage of engine warm-up and when the thrust is reduced or turned off.
Throttle Potentiometer
It sends a signal to the control unit about the movement of the throttle valve and its position. For example, the sudden release of gas is considered as acceleration. Information is received electrically. A potentiometer is nothing more than a variable resistance.
Coolant temperature sensor
The coolant temperature is needed to control many injection functions: to enrich the combustible mixture at a cold start, post-launch enrichment of the combustible mixture (over the entire temperature range), when accelerating and turning off the thrust Information about the temperature of the coolant is transmitted to the control unit also in the form of a resistance value. It calculates the correct injection time.
Impulse and knock sensor
The inductive pulse sensor is discussed in the chapter on ignition, which describes its operation and verification. The same applies to the knock sensor, which is only taken into account in the ignition part of the Multec central injection.
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