Table of contents: Cleanliness when working with the… ↓ Safety precautions when working with… ↓
The Motronic fuel injection system is an electronic system with a pre-programmed range of injection conditions, an ignition system controlled by the above range, with ignition timing that prevents detonation, built-in idle speed stabilization and fuel shut-off when coasting. This is the so-called multi-point injection, i.e. each cylinder has its own injector. The location of the main components of the system in the engine compartment is shown in the figure below. There are small differences between engines of different volumes, which will be discussed later, but which can also be seen in the figures.
Location of parts in the engine compartment
1 Output stage No.7 with ignition coil
2 Coolant temperature sensor (in the coolant pipe on the back of the cylinder head)
3 Distributor with Hall sensor
4 Throttle control unit
5 Plug connections for lambda probe, engine speed sensor, knock sensor
6 Motronic system control unit
7 Magnetic valve for activated carbon container
8 Air flow meter
9 Lambda probe with lambda probe heating
10 Injectors
11 Knock sensor
12 Engine speed sensor (behind the oil filter)
Cleanliness when working with the injection system
When performing work on the engine that requires disconnecting fuel injection system connections, the following precautions must be observed:
- Before unscrewing the union nuts, thoroughly clean them and the surrounding parts.
- Place the removed parts on a clean surface and cover them well with paper or plastic film, do not use rags for this. Do not touch the connections on the parts with greasy hands to prevent foreign objects from getting into the system.
- Removed parts that will not be used immediately should be stored in a box or other closed container.
- Remove new parts from packaging immediately before installation.
- If the system connections are open, do not use compressed air to blow off other parts. The vehicle should not be moved as much as possible. Open connections should always be well sealed.
Safety precautions when working with the system
Since the installed injection systems are electronically controlled and work in conjunction with the ignition system, the following precautions must be observed when working on the system to prevent damage and/or defects to the system.
When connecting or disconnecting electrical wires of the ignition system, injection system or measuring instruments, always switch off the ignition.
When turning the engine with the starter, so that the engine does not start (for example, when measuring compression), you need to disconnect the plug from the output stage of the ignition coils and the plugs from the injectors.
When starting from an external source, do not apply voltage greater than 16.5 V and do not crank the engine for more than 1 minute.
When cleaning the engine with cleaning fluids, turn off the ignition.
When performing any work on the vehicle, always disconnect both wires from the battery (AB).
When towing a vehicle with damage to the ignition or fuel injection systems, the plug must be disconnected from the output stage.