AUDI A6 1998 C5 / 2.G AHA Engine Multiport Fuel Injection And Ignition System User Guide

output stage, and fuse for fuel pump.
Disconnect harness connectors from all fuel
injectors.
Afterward, erase Diagnostic Trouble Code
(DTC) memory.
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CAUTION!

BEFORE disconnecting the battery:

Stop the engine.
Be sure the ignition is switched OFF (also
applies when connecting the battery). Failure
to do so may damage the Engine Control
Module (ECM).
Be sure of the proper radio code (for vehicles
equipped with coded anti-theft radio).

Be sure the battery negative (-) cable is
disconnected, when:
Working on the electrical system
Resistance (spot) welding or electric arc
welding anywhere on the vehicle.

When connecting and disconnecting
electrical test equipment (LED voltage tester,
multimeter, etc.):
Be sure the ignition is switched OFF.
Use correct adapters from the VW1594
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connector test kit.

For any work affecting the Engine Control
Module (ECM):
BEFORE disconnecting the ECM harness
connector, switch the ignition OFF and WAIT
at least 20 seconds. Failure to do so may
damage the ECM.
DO NOT connect any outside voltage source
to stimulate an output signal at the ECM.
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Rules of cleanliness


CAUTION!

Whenever carrying out work on the fuel
supply and fuel injection systems, carefully
observe the following rules of cleanliness.

- Thoroughly clean fuel system line and hose
connections and the surrounding area before
disconnecting.

- Place removed components on a clean surface
and cover. Use plastic sheeting or paper. Do not
use fluffy rags that could leave lint!

- Carefully cover over or seal any components
that have been opened if repairs are not carried
out immediately.

- Install only clean parts:


Do not remove replacement parts from the
packaging until immediately before they are
to be installed.

Do not use parts that have been stored
without packaging (e.g. in toolboxes, etc.).
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- When the fuel system is opened:


Avoid working with compressed air
whenever possible.

Avoid moving the vehicle if possible.
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24-13
Technical data

Engine code
AHA
Engine idle speed (with consumers
switched off)
not adjustable, maintained by Idle Air
Control (IAC) All-wheel drive vehicles 620-740 RPM
Front-wheel drive vehicles 740-860 RPM
Engine speed (RPM) upper limit
actuated by switching off fuel injectors approx. 6500 RPM
Fuel system pressure at idle With pressure regulator vacuum hose
connected approx. 3.2-3.8 bar
(46-55 psi)
With pressure regulator vacuum hose
disconnected approx. 3.8-4.2 bar
(55-61 psi)
Residual fuel pressure after 10 minutes Cold engine approx. 2.2 bar
(32 psi)
Warm engine approx. 3.0 bar
(44 psi)
Fuel injectors Spray pattern approx. the same for all fuel
injectors
Resistance 1)
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13.5-15.5 ohms ( )
1) Engine at room temperature; with the engine at normal operating temperature the resistance increases by approx. 4-6
ohms.
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24-14

Fuel injection system, servicing

Servicing ignition system page 28
-1

Notes:

Fuel hoses in the engine compartment must be
secured with spring-type clamps. Screw-type
clamps or equivalent must not be used.
The Engine Control Module (ECM) has On
Board Diagnostic (OBD) capability, and is
equipped with Diagnostic Trouble Code (DTC)
memory. Before repairing or adjusting any
components or systems, first check DTC
memory. Also check all vacuum connections for
leaks ("false air").
For proper operation of electrical and electronic
components, a Battery Positive Voltage (B+)
supply of at least 11.5 volts is required.
Do not use any gasket sealers or other
automotive chemical compounds that contain
silicone. Traces of silicone drawn into the
engine pass unburned into the exhaust and can
damage the oxygen sensors.
Do not use any electrical contact sprays or
equivalent near oxygen sensor connections.
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Proper oxygen sensor function requires
reference to outside air via the cable. If any
contact spray reaches the oxygen sensor, it can
cause damage or improper function.
During some tests, malfunctions are recognized
by the ECM and stored in DTC memory. For
this reason, always check DTC memory (
page 01
-16
) after all tests and repairs, and
erase DTC memory as necessary.
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24-15
Safety precautions page 24
-9
Rules of cleanliness page 24
-12

Technical data page 24
-13

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