Audi 80 Quiz
Ignition System

Control unit

In this manual: Ignition System
Technical Description — 39Engines — 41Exhaust System — 13Cooling System — 28Fuel tank and fuel pump — 12Air Filter and Intake Ducts — 13Mono-Motronic Injection System — 18Digifant Injection System — 19KE-III-Jetronic Injection System — 35MPI and MPFI Injection Systems — 32Clutch — 11Transmission and Driveline — 21Suspension and Steering — 33Brake System — 41Anti-lock brake system — 8Wheels and Tires — 13Body Electrical System — 35Ignition System — 24Lighting — 14Signaling Devices — 7Instruments and Auxiliary Equipment — 54Heating and Ventilation — 7Body Components — 18Troubleshooting — 6Specifications — 13
~2min read

On most engines, ignition control is integrated with fuel injection control. The only exception is the 5-cylinder engine: here the ignition system and the injection system each have their own control unit. However, there is no difference in how they operate. Below is a short list of the functions of the control unit.


Audi ignition systems do not require an additional device to regulate ignition timing. The control unit receives all kinds of engine data and values. These are supplied by the Hall sender or the engine speed and crankshaft position sender, as well as the engine temperature sender, throttle position sensor, etc. Based on all this data, the control unit calculates the correct ignition timing for the corresponding load condition.

If the ignition advance angle (ignition timing) is plotted against engine load and engine speed, the result is the so-called ignition map. Ignition maps of new ignition systems are often shown because of their unusual shape, from which conclusions can be drawn about the exact effect on operating conditions.

The control unit has correction programs, such as for engine starting, cold engine operation, overrun (deceleration) mode, etc.

The control unit supplies the ignition coil with exactly as much current as it needs at any given moment. In an extreme situation (ignition on, engine not running), these ignition systems cannot damage the ignition coil even after a long period of time.

Knock control (except on the model with a 66 kW engine) allows the engine to operate with the most accurate ignition timing and therefore with maximum power. For this reason, an engine designed for AI-95 (super) gasoline can also run on AI-92, since the control unit detects the lower octane number and switches to later ignition timing.

In addition, data is exchanged with the fuel injection system, since some sensors on the engine are used twice. This process takes place even on the 5-cylinder engine models, although here the ignition and injection systems have separate control units (KE-III-Jetronic and VEZ).

Finally, a fault memory is installed that records ignition system faults. Its memory can be read out in the workshop with a special tester (see also section Regular Maintenance).

Test yourself

A quick Audi 80 quiz: every answer comes with an explanation and a link to the manual page.