General information about the ignition system (VW Passat B3)

The ignition system produces an electric spark for each cylinder of a gasoline engine at the right time. This spark ignites the fuel-air mixture entering the cylinder. In the ignition coil, the battery voltage of 12 V is converted to a voltage of 25,000 to 30,000 V.

The ignition system consists of the following main elements:

• ignition coils
• spark plugs
• ignition distributor with Hall sensor and runner
• ignition control unit (TSZ, VEZ, Digifant, Motronic)

Carburetor engines, like engines with the Mono-Jetronic injection system, are equipped with a transistor ignition system (TSZ).

the 16-valve engine without a catalytic converter, designated KR, is equipped with a transistor ignition system with an additional control unit. This system is called an electronic ignition system (VEZ).

In engines with the Digifant ignition and injection system developed by VW, the VEZ system is integrated into the injection system control unit and is supplemented by a knock controller.

The Motronic system from BOSCH, installed on 16-valve and 6-cylinder engines, has only one ignition and injection control unit.

TSZ-H System

The transistor ignition system (TSZ) is contactless. Instead of a breaker, the ignition distributor is equipped with a maintenance-free Hall sensor (TSZ-H). A capacitor is not needed here. The Hall sensor consists of a contactless magnetic fence and a rotary diaphragm fixed to the distributor shaft.



The original article is posted on the website [VWmanual]

VEZ System

The electronic ignition system (VEZ) is a transistor system with an electronic control unit. The task of the ignition control unit is to regulate the ignition advance based on the characteristic fields once entered into the memory device (control cards). In the TSZ system, ignition timing is controlled by a vacuum-controlled centrifugal regulator.

Digifant ignition and injection system

In this system, electronic ignition and injection control are combined in one unit. This is a transistor ignition system with a Hall sensor and an electronic ignition advance control unit. The ignition advance is regulated based on ignition characteristic fields that have been stored in the memory device. In terms of design, the Digifant system basically corresponds to the VEZ ignition system. However, the signal from the knock sensor also influences the ignition timing.

Ignition and injection system KE - Motronic

The ignition distributor with a Hall sensor is similar in design to that used in the VEZ system. The ignition timing is also adjusted based on the ignition characteristic fields that have been stored in the memory device. The ignition coil voltage output stage, comparable to the TSZ-H switch of other ignition systems, is located next to the ignition coil and is designed to control the ignition coil current based on the control unit signals. Thanks to two knock sensors, the occurrence of knock in each individual cylinder is detected, and the ignition timing for such a cylinder is automatically changed. In addition, an induction sensor is installed on the high-voltage wire for cylinder 4, which, at the moment of spark occurrence, sends a voltage signal to the control unit, which is necessary for using the signals from the knock sensors.

Motronic M2.7/M2.9 system in a 6-cylinder engine

While the M2.7 system still has an ignition distributor, in vehicles with chassis numbers starting with 31 ZNE 139 739 (since about 9/92), a contactless ignition system is used. The distribution of high voltage to individual cylinders is carried out here with the help of electronically controlled parts operating in static mode, which replaced the traditional mechanical distributor with a runner. The system has 3 ignition coils located in one housing, which are fixed to the engine cylinder head. Synchronization of the ignition system is carried out with the help of signals that the Hall sensor sends to the control unit. The sensor is located on the side of the cylinder head and measures the rotation frequency of the camshaft.

Digifant and Motronic systems: self-diagnosis

The Digifant system for 2.0 l 8/92 engines, like all Motronic systems, has a self-diagnosis capability. This means that faults that occur in the injection and ignition system are stored in the memory of the control unit in the form of codes. These codes can be read in a VAG workshop, after which the detected faults are specifically eliminated.