1997 AUDI A4 EVAP Workshop Manual

20-137

Note:
Observe the cover flange installation instructions.

Front wheel drive Page 20
-44


All wheel drive Page 20
-97
.

- Visually inspect all fuel tank system line and
hose connections and replace any leaking lines,
for example:


Line from EVAP canister to EVAP canister
purge regulator valve in engine
compartment.

Lines from EVAP canister to the LDP (under
left wheel house liner).

Line from the fuel tank to the EVAP canister
(under the cover for the EVAP canister).

Lines of the tank ventilation system (under
right wheel house liner).

Fuel lines to the engine.

Note:
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Locate leaks at lines and components of the tank
system by using a non-combustible,
environmentally friendly, leak detector spray.
Perform several leak diagnostics in a row to build
up the system pressure. Bubbles will form at
points of leakage.
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20-138

- Visually inspect the fuel supply system
components:


Fuel tank

EVAP canister

LDP

EVAP canister purge regulator valve -N80

Note:
At times, the above components cannot be
effectively leak tested using a leak detection
spray, either because of component location or
function. In such cases, clamp off the lines to the
component involved and perform a leak check. If
the leak is no longer displayed, the clamped off
component is faulty. If the LDP is clamped off
and there is still a leak displayed, the LDP is
faulty.

- Check EVAP canister purge regulator valve -
N80

Repair Manual, Fuel Injection & Ignition,
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Repair Group 24
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20-139


Leak Detection Pump (LDP) -V144,
checking

Special tools needed:
or
Observe Safety measures Page 20
-1 .
Observe Rules of cleanliness Page 20-4 .
VAG1526 A
VAG1527 B
VAG1594 A
VAG1598/22 (vehicles with mechanical
accelerator cable)
VAG1598/31 (vehicles with electronic throttle
control
VAS5051 with VAS5051/1
VAG1551 with VAG1551/3 A
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20-140

Checking LDP via Read Measuring Value
Block (vehicles with mechanical throttle
control)

Note:

Always replace O-rings, sealing rings and
gaskets.
Radiator fan must not come on during the
test!

Troubleshooting requirements
DTC memory checked and no DTCs stored
All electrical consumers switched OFF
A/C switched OFF
Intake Air Temperature lower than 90 C
Display group 004, channel 4.

Engine Coolant Temperature less than 95
C Display group 004, channel 3.

Throttle angle less than 10 % Display
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group 003, channel 3.
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20-141


Note:
In the following description the performance of the On Board Diagnostic
(OBD) procedure the VAG1551 Scan Tool (ST) is used. When using
Vehicle Diagnostics Test and Information System VAS5051, use the
operating instructions. - Connect VAS5051 with diagnostic cable VAS5051/1 or VAG1551 Scan
Tool (ST) with adapter cable VAG1551/3B.
- Start engine and let idle.
On Board Dia
gnostic
HELP
1 - Rapid data transfer 1
)
2 - Blink code 1
)

Indicated on display: 1) Appears alternately
- Switch ignition on.
- Press button 1 to select "Rapid data transfer".
Rapid data transfer
HELP
Enter address word XX

Display will appear as shown
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