Control block
The control unit receives the following types of information via the multi-pin plug from:
Starter from terminal 50 - about the beginning and end of the starting process.
Throttle potentiometer - about the current position of the throttle.
Hall sensor in the ignition distributor - about the engine speed.
Lambda probe in the catalytic converter - about the content of residual oxygen in the exhaust gases.
Potentiometer in the air flow meter - on the position of the check valve (intake air).
Intake air temperature sensor in the air mass meter.
Coolant temperature sensor in the cooling system pipe.
Knock sensor on the cylinder block for «detonation» combustion, see also chapter «Ignition system».
Based on the information about the speed and load, the control unit calculates the duration of the opening of the electromagnetic injection nozzles driven by the electromagnet, and thus the amount of fuel injected. To do this, the control unit has the injection characteristics and, in addition, the ignition characteristics. These characteristics are a data file for all possible situations in the operation of the engine and the corresponding amounts of fuel, as well as ignition timing. The control unit can change these indicators after receiving the so-called corrective signals.
Throttle valve
Two throttle valves are located in a pipe in the intake manifold. The smaller of these dampers is connected by a drive cable «gas» with a pedal in the cabin. It doses the flow of intake air into the engine. If the accelerator pedal is pressed harder, then the rod opens the second, larger flap, in the full position «gas» both dampers are open.
Throttle Potentiometer
The throttle potentiometer covers the current throttle position from «idle move» (throttle closed) before «full load» (throttle valve fully open). Based on its information, idle stabilization is activated, fuel is cut off in forced idle mode, or the combustible mixture is enriched when the throttle is fully opened.
Pressure regulator
It is located in front of the fuel distributor and regulates the fuel supply pressure to the injection nozzles. To do this, it receives information about the state of vacuum in the intake manifold. At idle at closed throttle and high vacuum, it holds a lower pressure. When the vacuum decreases with a greater engine load, the pressure regulator increases the fuel supply pressure. The fuel pump delivers fuel at a higher working pressure, but thanks to the pressure regulator, the flow of gasoline back into the fuel tank is correspondingly increased or, if necessary, reduced.
Nozzles
With each turn of the crankshaft, they inject gasoline into the injection channel in front of the intake valve of the corresponding cylinder - the duration of this process is determined by the control unit. The corresponding cylinder receives one portion in reserve, and the second with the intake valve open directly into the combustion chamber:
Intake air temperature sensor
It is located on the side of the air mass meter and thus can accurately determine the temperature of the incoming air. The intake air temperature enters the control unit in the form of a resistance reading. This indicator is needed for the optimal dosage of fuel.
This illustration is a schematic representation of the Digifant injection system with its components. The air path is shown by white arrows, the fuel supply is represented by red. The numbers indicate:
1 - fuel tank;
2 - fuel filter;
3 - pressure regulator;
4 - fuel distributor;
5 - nozzle;
6 - intake manifold;
7 - air flow meter;
8 - idle stabilization valve;
9 - fuel pump.
Coolant temperature sensor
Coolant temperature is required to control many injection functions. Information about the temperature of the coolant enters the control unit also in the form of a resistance indicator. The control unit calculates the required injection duration, which, when the engine is warmed up to operating temperature, is in the range between two and eight milliseconds. This figure can increase to 70% if the coolant temperature reaches -25°C.
Air mass meter
The air required for combustion from the air filter is more or less (depending on the input amount) pushes aside the shutter in the air flow meter, while the damping valve associated with the shutter prevents vibrations of the shutter. The potentiometer sends a signal in the form of voltage to the control unit depending on the position of the valve shutter: high voltage at full opening and a large amount of air, low voltage at small opening.
Start fuel valve
This solenoid-driven injection nozzle sprays additional fuel into the injection manifold for 1-4 seconds, depending on the engine temperature at start-up. The duration of the injection is determined by the control unit of the Digifant injection system.
Idle stabilization valve
In the warm-up phase, when the power steering is fully turned, when the air conditioner is running, or when the automatic transmission stage is engaged, this valve releases an additional air passage, thereby bypassing the throttle valve. The increased air exchange in the direction of the intake manifold at the same time leads to an increased fuel supply. The valve for stabilizing the engine shaft speed in idling mode is also used in forced idling mode. It allows you to enter the amount of air necessary for movement with the throttle closed.
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