Vehicle ignition system Audi 100 C4, petrol

What can ignition do?
In order for a spark to jump through the spark plug in the combustion chamber, there must be a voltage of at least 30,000 V between the spark plug electrodes....

When does ignition occur?
The spark must fly at exactly the right moment. However, determining when that very right moment will be is not so easy. Combustion is most efficient when the...

Various ignition systems
The ignition system is an integral part of the engine electronics in almost all Audi 100 models. But what looks complicated on paper is actually relatively...

This is how the spark is created
The basic principle of ignition is that current from the battery first goes to the primary winding of the ignition coil. This winding consists of several turns...

Executive body
Electronic transistor switch The electronic switch contains a powerful transistor that turns the current supply to the ignition coil on and off (or to the...

The «brain» of the system
Control unit In most engines, the ignition system control is integrated with the injection system control. The only exceptions are models with a 5-cylinder...

Pulses for the control unit
Hall sensor The switching on and off of current to the ignition coil mentioned in the section is provided (also passing through the control unit and the...

Knock control
Except for 74 kW motors Detonation combustion, which occurs when the ignition timing is moved too far in the "spark advance" direction, is harmful to the...

Safety precautions when working with the ignition system
In the engine compartment of the Audi-100, a special sign warns of high voltage in the ignition system, and this is not without reason: even in the thin wire...

Ignition system repair
"Disabling" the ignition system The control unit or the electronic switch of the ignition coil will definitely be damaged if the engine is turned with the...

Ignition system diagnostics
Anyone who wants to find a fault in the ignition system must act according to the system. A simple secondary voltage test can be used to determine whether an...

Ignition distributor
The ignition distributor is, in a certain sense, two-level. At each level, different work is performed: In the high-voltage element, the distributor runner...

Detonation combustion sensor
Except for 74 kW motors The knock sensor is checked by interrogating the fault memory (see also chapter " Regular maintenance "). There are no other options...

High voltage elements
High voltage wires The high-voltage part of the ignition system includes, in addition to the ignition coil and distributor - which have already been discussed...

Replacing spark plugs
TO No.36 The maintenance plan provides for replacement of spark plugs every 30,000 km. This interval seems realistic to us and should not be extended. It is...

Spark plugs
Spark plug designations With the designations in the table on the next page, you will purchase spark plugs that match your vehicle. What is hidden behind the...

Checking the ignition timing
TO #6 The ignition timing, in fact, cannot be lost in the electronically controlled ignition systems of the Audi-100. The workshop also checks the ignition...

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100(C4, 1990-1994)

100(C4, 1990-1994, petrol)

100(C3, 1982-1990)

100(C3, 1982-1990, petrol)

100(C3, 1982-1990, diesel)