ignition AUDI A4 1997 B5 / 1.G AHA Engine Multiport Fuel Injection And Ignition System Workshop Manual

24-1


Motronic Multiport Fuel
Injection (MFI) and ignition
system Component locations

Data Link Connector (DLC)
Fuel pump relay
Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC) -G130-, with Oxygen
Sensor (O2S) heater -Z29-
Located under knee bar, left side of steering
wheel
Position 6 on relay panel in driver's side footwell
Bank 1, sensor 2
In exhaust system behind TWC
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24-7


21 -
Engine speed (RPM) sensor -G28-
In transmission housing above differential
22 -
Camshaft Position (CMP) sensor -G40-,
bank 2
23 -
Heated Oxygen Sensor (HO2S) 2 -G108-
with Oxygen Sensor (O2S) heater -Z28- Bank 2, sensor 1
24 -
Knock Sensor (KS) 2 -G66-
25 -
Ignition coils and power output stage
Includes:Ignition coil -N-Ignition coil 2 -N128-Ignition coil 3 -N158-Power output stage -N122-
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24-10

WARNING!

Be alert when working on or near the engine
and ignition wires. High secondary ignition
voltage can cause serious personal injury
and damage vehicle components.

DO NOT touch or disconnect ignition system
wires when the engine is running or being
cranked at starting RPM.
DO NOT operate the starter if fuel injectors
are removed.

Be sure the ignition is switched OFF, when:
Disconnecting or connecting the battery,
ignition wires, or test equipment leads
Disconnecting fuel injection system wiring
Washing the engine or engine
compartment.

BEFORE cranking the engine at starting RPM
(e.g. for compression testing) disable ignition
and fuel injection systems:
Disconnect connector for ignition coil power
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24-11

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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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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24-16

Idle speed, checking


Notes:

Idle speed, ignition timing and CO-content
cannot be adjusted.
Idle speed is maintained by the Throttle valve
control module.
CO-content is maintained and adjusted by
Oxygen Sensor (O2S) control. Malfunctions in
O2S control are recognized by On Board
Diagnostic (OBD) and stored in DTC memory.

Required special tools and test equipment
VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
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- Switch ignition off.
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24-29

Checking HO2S reference voltage (Banks 1,
2)

- Disconnect 4-pin connector for respective
HO2S.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring.

Bank 1, sensor 1 page 24
-30
.

Bank 2, sensor 1 page 24
-32
.
- Replace respective Heated Oxygen Sensor (HO2S).
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input.

- Switch ignition off.
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