AUDI A4 1995 B5 / 1.G AHA ATQ Engines Secondary Air System Workshop Manual

26-12


Secondary Air Injection (AIR)
system

Check Diagnostic Trouble Code (DTC)
memory.

Repair Manual, 2.8 Liter V6 5V Fuel Injection
& Ignition, Repair Group 01

Initiate output Diagnostic Test Mode (DTM).

Repair Manual, 2.8 Liter V6 5V Fuel Injection
& Ignition, Repair Group 01

Initiate "Basic Setting" (scan tool function 04).

Repair Manual, 2.8 Liter V6 5V Fuel Injection
& Ignition, Repair Group 01

Check Secondary Air Injection (AIR) valve.

Repair Manual, 2.8 Liter V6 5V Fuel Injection
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& Ignition, Repair Group 01

Notes:

The secondary air injection system injects air
behind the exhaust valves during a cold start.
Cold start means engine coolant temperature
between 8-65 C (46-149 F). The amount of
air injected is temperature dependent.

The need for secondary air is triggered by the
Motronic Engine Control Module (ECM) -J220-
via the Secondary Air Injection (AIR) Injection
pump relay -J299- to the Secondary Air
Injection (AIR) solenoid valve -N112- and the
two combination valves.
When "Basic Setting" (scan tool function 04) is
initiated, a diagnosis for the secondary air
injection system can be carried out. The
diagnostics consists of a flow test and a leak
test.
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26-13

Flow test
During the flow test, the oxygen sensor control is
switched off (engine runs rich at that time). At the
same time the secondary air injection pump is
switched on, injecting fresh air into the exhaust
manifold which increases the oxygen content in
the exhaust gas. The oxygen sensor now
measures a lean mixture. To pass the diagnostic
test, the oxygen sensor must measure a lean
mixture for a certain time. Passing the test
means that the secondary air injection system
delivers enough air and the secondary air
injection system is OK.

Leak test

Flow test must check out OK
Engine at operating temperature
The secondary air injection pump is switched on
during idle. Since the combination valves are not
triggered by the secondary air injection solenoid
valve, they remain closed. When the secondary
air injection pump is switched on, the oxygen
sensor system is monitored by the ECM. If the
system does not leak, fresh air cannot enter the
exhaust manifold. If the system is leaking, the
oxygen sensor signal will respond to the leaner
mixture (caused by the secondary air getting into
the exhaust manifold) and cause a noticeable
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enrichment. This enrichment is recognized by the
ECM.
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26-14


Secondary Air Injection (AIR) system,
overview

1 -
Motronic Engine Control Module (ECM) -
J220-
2 -
Air cleaner
Connection for intake air of Secondary Air
Injection (AIR) pump
3 -
Secondary Air Injection (AIR) pump motor
-V101-
4 -
Connection Between air cleaner and secondary air
injection pump Removing page 26
-16
5 -
Vacuum line
Control line between Secondary Air
Injection (AIR) solenoid valve -N112- and
combination valves
6 -
Connection tube From secondary air injection pump to
combination valves
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26-15


7 -
Combination valves
Located at rear of left and right cylinder
heads Removing and installing page 26
-16
8 -
Engine
9 -
Right exhaust manifold
10 -
Left exhaust manifold
11 -
Secondary Air Injection (AIR) solenoid
valve -N112-
12 -
Vacuum reservoir
Located in left-front wheelhousing
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26-16

Secondary Air Injection (AIR) system
components, removing and installing

Component locations page 26
-14
.
Fuel injection and ignition components.

Repair Manual, 2.8 Liter V6 5V Fuel Injection
& Ignition, Repair Group 24
Note:
Always replace gaskets and seals.

A - Combination valve, left

- Remove engine coolant expansion tank from
bracket.

- Disconnect vacuum line -1-.
- Disconnect connection tube -2- from combination valve.
Tightening torque: 10 Nm (7 ft lb).
- Remove bolts -3- for combination valve from cylinder head and remove
valve.
Tightening torque: 10 Nm (7 ft lb).
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26-17

B - Combination valve, right

- Remove intake air duct between Mass Air Flow (MAF) sensor and
intake air elbow (three -arrows- on right).
- Remove intake air elbow from throttle body connector.
- Disconnect harness connector for Evaporative Emission (EVAP)
canister purge regulator valve (left arrow) and pull valve out of bracket.
- Disconnect harness connector at Mass Air Flow (MAF) sensor.

- Turn connector tube for Secondary Air Injection (AIR) pump 1/4-turn
(45 ) to right and pull forward off air cleaner. - Remove air cleaner housing.
Tightening torque: 20 Nm (15 ft lb).
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26-18


C - Secondary Air Injection (AIR) pump motor - Remove vacuum line -1-.
- Disconnect connection tube -2- from combination valve.
Tightening torque: 10 Nm (7 ft lb).
- Remove bolts -3- for combination valve from cylinder head and if
necessary, remove bracket -4- from cylinder head.

Bolt -3- tightening torque: 10 Nm (7 ft lb).
Bracket -4- tightening torque: 20 Nm (15 ft lb).
- Remove combination valve.

Repair Manual, Body Exterior, Repair Group 63

Repair Manual, Body Exterior, Repair Group 50 - Remove noise insulation panel (arrows).
- Remove front bumper.
- Move lock carrier into service position.
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26-19


- Remove air duct to generator at front of air shroud.
- Disconnect connection at connector tube to Secondary Air Injection
(AIR) pump combination valves (left arrows), pull down to remove and
cut tie wraps.
- Remove three bolts on Secondary Air Injection (AIR) pump (lower right
arrows) but do not remove nuts.
- Remove pump toward rear from bracket.
- Remove connection line on Secondary Air Injection (AIR) pump to air
cleaner.

Installing
Installation is the reverse of removal. -
Turn connector tube for Secondary Air Injection (AIR) pump 45 to
right and disconnect. - Remove air Secondary Air Injection (AIR) pump.
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