Control block
For most engines, the ignition system control is integrated with the injection system control. The only exceptions are models with a 5-cylinder engine: here each system has (ignition and injection) your own control box. But there is no difference in the mode of action. Below is a small list of what the control unit does.
The ignition systems of Audi vehicles do not need an additional device to control the ignition timing. The control unit has all kinds of engine data and indicators at its disposal. Their receipt is provided by a Hall sensor or a sensor for engine speed and crankshaft position, as well as sensors for engine temperature, throttle position, etc. From all this data, the control unit calculates the correct ignition timing for the respective load condition.
If you depict the ignition timing (ignition timing) depending on the load and engine speed, we get the so-called ignition characteristic. The characteristics of new ignition systems are readily depicted because of its bizarre shape - it can be used to draw a conclusion about the exact impact on operating conditions.
The control unit has at its disposal correction programs, such as: for starting the engine, running a cold engine, driving in forced idle mode, etc.
The control unit always allows exactly as much current to the ignition coil as it needs at a given time. In an emergency (ignition on but engine not running) With these ignition systems, damage to the ignition coil cannot occur even after a long time.
Knock control of the 85, 98 and 110 kW engine makes it possible to operate the engine with the most accurate ignition timing, and therefore with the highest power. Therefore, an engine designed to run on AI-95 gasoline (super), can also work on AI-92 gasoline, since the control unit recognizes a lower octane number and switches to a later ignition mode.
If you build a diagram of the dependence of the advance angle on the load and the engine speed, then you get the so-called ignition characteristic. The weirder its shape looks, the more precisely the ignition is matched to the corresponding operating situation of the engine.
Left: open ignition distributor (on the example of a 4-cylinder engine):
1 - Hall sensor;
2 - contactor;
3 - connecting plug of the Hall sensor.
Right: The Hall effect sensor is located far behind the left cylinder head on the 6-cylinder engine.
The illustration shows:
1 - Hall sensor housing;
2 - connecting plug.
Knock control is also available on the 128 kW 6-cylinder engines. However, AI-95 gasoline is used here, and AI-92 is not allowed to be used in this engine. Those who wish can also use super plus lead-free gasoline. The control unit responds to it accordingly, which improves the dynamism of the car.
The 74 kW engine has no detonation control and runs on AI-92 gasoline.
Of course, there is an exchange of data with the injection system. This process is carried out even on models with a 5-cylinder engine, although here the ignition and injection systems are equipped with different control units (KE-III-Jetronic and VEZ).
And finally, a fault memory is installed that records the defects of the ignition system, the memory of which can be interrogated in the workshop with a special device (see also chapter «Regular maintenance»).
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