open AUDI TT 1996 8N / 1.G ATW Engine Motronic Fuel Injection Syst

24-2

It is possible that the control module will
recognize a malfunction and store a DTC during
some tests. After completing all tests and
repairs, DTC memory should therefore be
checked and erased if necessary. Readiness
code must be generated after DTC memory is
erased Page 01
-73
.

Always switch ignition off before cleaning
engine.
The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.

WARNING!

Fuel system is under pressure! Before
opening system, place rags around the
connection point. Then release pressure by
carefully loosening connection.
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24-3

Rules of cleanliness

When working on the fuel supply or fuel injection
systems, the following "6 rules of cleanliness"
should be carefully observed:

Thoroughly clean all connections and the
surrounding area before disconnecting.
Place parts that have been removed on a clean
surface and cover. Use lint-free cloths only!
Carefully cover over opened components or
seal, if repairs are not carried out immediately.
Only install clean components:Only unpack
replacement parts immediately prior to
installation. Do not use parts that have been
stored loose (in tool boxes etc.)
When the system is open:Do not work with
compressed air if it can be avoided. Do not
move vehicle unless absolutely necessary.
Disconnected electrical harness
connectors:Protect from dirt and moisture. Be
sure harness connector is dry before
connecting.
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24-9


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 26; Secondary Air Injection (AIR) system, checking
13 -
E-box, plenum chamber Installation locations Page 24
-15
, Fig.
6

Installation location for motronic Engine
Control Module (ECM) -J220- with
integrated Barometric pressure (BARO)
sensor -F96- Check voltage supply of Engine Control
Module (ECM) Page 28
-36

Procedure to follow after open circuit in
voltage supply Page 24
-22

Replacing Engine Control Module (ECM)
Page 24
-23

Installation location of Secondary Air
Injection (AIR) pump relay -J299- Check Secondary Air Injection (AIR) pump
relay -J299-:
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24-32

If idle speed is too high or low and there are
no DTCs in DTC memory, the following tests
(marked with dots) must be performed:

Check for false air in intake air system
Page 24
-68
.

Check throttle valve control module Page 24
-120
.

Evaporative Emission (EVAP) canister purge
regulator valve always open, checking
Page 24
-107
.

Perform adaptation of throttle valve control
module Page 24
-121
.
Significance of 5 digit indication of display group 056 x
x
x
x
x
Display field 4
0 A/C compressor: 0 = A/C compressor off; 1 = A/C compressor on
0 Manual transmission: Indication always 0
Driving mode for automatic transmission: 0 = selector lever in P or N; 1 = selector lever in 2/3/4/D/R
0 Indication always 0
0 Indication always 0
0 Indication always 0
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24-34

Checking system pressure

- Open fuel filler flap briefly (pressure release).

WARNING!
Fuel system is under pressure! Before opening system, place rags
around the connection point. Then release pressure by carefully
loosening connection. - Remove engine cover (arrows).

- Open threaded connection (arrow) and catch exiting fuel using a rag.
- Connect VAG1318 pressure gauge in supply line using adapters
1318/11, 1318/12 and 1318/13.
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24-35


- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Measure fuel pressure.

Specification: about 3.5 bar positive pressure

- Disconnect vacuum hose at fuel pressure regulator.

Fuel pressure must rise to about 4.0 bar positive pressure.
- Switch ignition off.
- Check for proper seal and residual pressure by observing pressure
drop on pressure gauge.
After 10 minutes, there must be at least 2.5 bar positive pressure
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24-36
If residual pressure sinks below 2.5 bar positive
pressure:

- Start engine and let run at idle.

If pressure does not drop now:
If pressure drops again:
If pressure does not drop now: - Wait until pressure has dropped, and then switch off ignition.
Simultaneously close shut-off valve of VAG1318 pressure gauge (lever
perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.
- Test check-valve on Fuel Pump (FP).
- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Wait until pressure has dropped, and then switch off ignition.
Simultaneously clamp return line (with blue marking) completely
closed.
- Replace fuel pressure regulator
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24-37
If pressure drops again:

- Check wire connections, O-rings at fuel
distributor and fuel injectors for proper seal.

- Check whether pressure gauge is properly
sealed.

Note:
Before disconnecting pressure gauge, release
pressure by opening shut-off valve. Hold a
container in front of connection for this.
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Electrical Wiring Diagrams, Troubleshooting & Component Locations - Check wire connection between terminal 1 and fuse for injector valves
for open circuit:
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24-41

- Repair open circuit if necessary.
If LED lights up:

- Activation of fuel injectors, checking

Checking activation

Test requirement:

Internal resistance of valve OK

- Slide back rubber grommet of fuel injector
connector, but leave connector connected.

Note:
Voltage testers do not go out completely during low current pick-up
between activations by the ECM, but rather continue to glow a little and
then get slightly brighter during activation. - Connect VAG1527B voltage tester between sockets 2 (signal) and 1
(B+).
- Operate starter briefly (engine can also start).

LED must blink.
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