Starting a cold engine
When starting a cold engine, the idle air stabilization valve through a separate channel increases the intake air. At the same time, the system control unit receives information from the coolant temperature sensor that the engine is cold. The control unit responds to the information received by increasing the duration of fuel injection, ensuring the formation of a fuel-rich mixture. In addition, the control unit includes a starting fuel solenoid valve, which sprays additional fuel into the intake manifold.
Engine warm-up
The coolant temperature sensor informs the electronic control unit of an increase in coolant temperature. The control unit, in response to this information, closes the idle stabilization valve, and the duration of fuel injection decreases and remains within normal values.
Idling
The idling mode is recognized by the electronic control unit based on information from the throttle angle potentiometer and the potentiometer on the intake air flow meter. When the engine idle speed decreases, the control unit changes the ignition timing. At the same time, the idle control valve opens, supplying additional air and causing a slight increase in fuel injection.
During the design operation mode, all auxiliary components of the system are usually not involved. The position of the throttle valve and the valve shutter of the air volume meter are decisive for the duration of the opening of the nozzles.
Acceleration, acceleration
The electronic control unit receives information about the rapid opening of the throttle valve from a message from the throttle angle potentiometer and reacts to this by increasing the duration of the opening of the injectors.
CO content regulation
In order for the catalyst to work flawlessly, it needs a constant alternation of rich and lean air-fuel mixtures. Information about the oxygen level in the exhaust gases at the current moment is reported to the electronic control unit by an oxygen sensor (Lambda probe) on the catalyst. In a fraction of a second, the electronic control unit reacts to this by reducing or increasing the duration of the opening of the nozzles, thereby regulating the composition of the air-fuel mixture.
Forced idle mode
Information that the driver has released the accelerator pedal is also sent to the control unit from the throttle angle potentiometer. And if at the same time the coolant temperature sensor informs the control unit that the engine has an operating temperature, and the Hall sensor informs that the engine speed is above 1500 rpm, then the control unit closes the nozzles.
Full operating load
The engine needs more fuel to run at full load. This mode is recognized by the electronic control unit on the basis of data from the throttle angle potentiometer and increases the duration of the opening of the injectors. Lambda probe signals are ignored.
Engine speed limitation
To protect the engine, the electronic control unit turns off the nozzles when it receives information from the Hall sensor that the engine speed is 6400-6500 rpm.
Emergency program
If one of the sensors fails, if the necessary contact with the corresponding sensor is broken, or if a situation arises when the sensor starts to give meaningless information, the Digifant system continues to function. In this case, the memory of the electronic control unit contains the data of the so-called emergency program, which cannot be changed. This program cannot take into account much of what is normally perceived by the system, but it keeps the engine running. A decrease in the effective power of the engine or a deterioration in its start is evidence of the failure of one of the sensors.
The control unit recognizes and registers some of the malfunctions in the operation of the engine in a memory device (drive). Workshops, when performing service work and during vehicle maintenance, interrogate the memory device using the appropriate VAG 1551 device and print out the entire list of registered faults. If the owner of the car assumes a malfunction of the fuel injection system, then by contacting the workshop, he can receive a corresponding printout of the faults, as well as professional assistance in eliminating the defect. After the problem is fixed, it is removed from the list.
Attention! When performing checks or adjustments during which the coolant sensor plug was disconnected, the self-diagnosis tool registers the absence of a signal from this sensor. For this reason, when performing work related to disconnecting the coolant sensor plug, it is recommended that you contact a workshop to print out and delete records of this malfunction.
Visitor comments