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24 – Mixture preparation - injection
1 Servicing injection system
1.1 General notes on self-diagnosis
♦ The engine control unit has a self-diagnosis capability. Before
carrying out repairs and fault finding the fault memory must be
interrogated. The vacuum hoses and connections must also
be checked (unmetered air).
♦ Fuel hoses in engine compartment must only be secured with
spring-type clips. Clamping-type or screw-type clips must not
be used.
♦ A voltage of at least 11.5 V is required for proper operation of
the electrical components.
♦ Do not use sealants containing silicone. Particles of silicone
drawn into the engine will not be burnt in the engine and will
damage the Lambda probe.
♦ The vehicles are fitted with a crash/fuel shut-off system. This
system is designed to reduce the risk of a vehicle fire after a
crash by deactivating the fuel pump via the fuel pump relay.
♦ At the same time, this system also improves the engine's start‐
ing performance. When the driver's door is opened, the fuel
pump is activated for 2 seconds in order to build up pressure
in the fuel system → Chapter (page 1).
1.2 Safety precautions
WARNING
The fuel system is pressurised. The fuel pressure in the high-
pressure part of the injection system must be reduced to a
residual pressure prior to opening; for procedure see
→ Chapter (page 3).
The connection must be opened IMMEDIATELY after reduc‐
ing the pressure by wrapping a cloth around the connection
and allowing the residual pressure (approx. 6 bar) to dissi‐
pate.
Note the following if testers and measuring instruments have to
be used during a road test:
WARNING
♦ Test equipment must always be secured on the rear seat
and operated from that position by a second person.
♦ If test and measuring instruments are operated from front
passenger's seat and the vehicle is involved in an acci‐
dent, the person sitting in this seat could be seriously
injured when the airbag is triggered.
Audi A3 2004 ➤
Direct petrol injection and ignition system (4-cyl. 2.0 ltr. 4-valve turbo) - Edition 11.2005
1. Servicing injection system 1
