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24 - Mixture preparation, Injection
1 - Servicing Motronic injection system
1.1 - Servicing Motronic injection system
1.2 - Safety precautions
Observe the following precautions if test and measuring instruments are required during a test drive:
Warning:
◆ Test equipment must always be secured on the rear seat and operated by a second person.
◆ If test equipment is operated from the front passenger's seat, the occupant could be injured by the pas‐
senger's airbag in an accident.
To prevent injuries to persons and/or damage to the fuel injection and ignition system, the following must be
noted:
◆ Always switch off the ignition before connecting or disconnecting injection or ignition system wiring or tester
cables.
◆ To operate the engine at starting speed without actually starting it (for example, in order to test compression),
unplug the connectors from the output stages for the ignition coils and also the connectors on the injectors.
◆ During some of the tests the control unit may identify and record faults. The fault memory should therefore
be interrogated and (if necessary) erased after completing the tests and any repair work that may be re‐
quired.
◆ Always switch off the ignition before cleaning the engine.
◆ Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine control
unit may be damaged.
Warning!
The fuel system is pressurised. Before loosening hose connections or opening the test connection (to measure
fuel pressure), place a cloth around the connection. Then release pressure by carefully pulling off the hose or
cap.
1.3 - Rules for cleanliness
When working on the fuel supply/injection system, pay careful attention to the following rules for cleanliness:
◆ Thoroughly clean all unions and the adjacent areas before disconnecting.
◆ Place parts that have been removed on a clean surface and cover them over. Do not use fluffy cloths.
◆ Carefully cover over or seal opened components if the repair cannot be carried out immediately.
◆ Only install clean components:
Only unpack replacement parts immediately prior to installation.
Do not use parts that have been stored loose (e.g. in tool boxes etc.).
◆ When the system is open:
Do not work with compressed air if this can be avoided.
Do not move vehicle unless absolutely necessary.
◆ Unplugged electrical connectors:
Keep clean and dry.
Audi A8 1994 ➤
Motronic injection and ignition system (6-cylinder) - Edition 02.1999
22
24 - Mixture preparation, Injection
