AUDI A4 1997 B5 / 1.G AEB Engine EVAP System Checking

24-136


Evaporative Emissions
(EVAP) system, checking

CAUTION!

Whenever carrying out work on the fuel
supply and/or fuel injection systems, read
and carefully follow the Cautions, Warnings,
and rules of cleanliness Page 24
-5 .

Note:

Always replace gaskets, O-rings and hose
clamps.
Hose connections must be secured with screw-
type clamps or band clamps.
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24-137

Leak Detection Pump (LDP), checking


Electrical testing

If resistance is NOT OK: - Disconnect harness connector for LDP -V144-.
- Connect multimeter US 1119 (Fluke 83 or equivalent) and check
resistance at leak detection pump. Specified values:

Connector terminal 1 to terminal 3: 640-720

Connector terminal 2 to terminal 3: 17.5-27.5
- Replace leak detection pump -V144-.
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porative Emissions
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24-138

Voltage supply, checking

If LED tester does not light: - Disconnect harness connector for LDP -V144-.
- Connect VAG 1527B LED voltage tester between connector terminal 3
(B+) and engine Ground.
- Start engine and run engine at idle.
LED must light up.
- Check fuse for LDP -V144-.
- Check wiring for open circuit between terminal 3 and fuse, according to
wiring diagram. Specified value: max. 0.5 . - Check fuel pump relay and signal to relay Page 24
-81
.
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porative Emissions
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24-139

Evaporative Emission (EVAP) Canister
Purge Regulator Valve, checking


Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable

Test conditions
Engine coolant temperature at least 80 C
(176 F)

Function check

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP
Selectin
g function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -7- and -0- to input display group number 70, and
press -Q- button to confirm input.
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porative Emissions
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Read Measuring Value Block 70 1 2 3 4

Indicated on display (1-4 = display fields)
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24-140

- Press -4- button- to select "Basic Setting"
function 04 (diagnosis for EVAP canister purge
regulator valve is initiated).

Note:
During this diagnosis there should not be any
load placed on the engine, otherwise the
diagnosis is interrupted and must be started
again. System in Basic Setting 70 1 2 3 4

Indicated on display (1-4 display fields)
If the diagnosis is initiated by the ECM, the display changes from "Test
OFF" to "Test ON" in display field 4.
Note:
If the display changes from "Test ON" to "Test OFF" during the test,
accelerate with a brief burst to repeat the test. - Continue to run engine at idle until "EVAP OK" is indicated in display
field 4.
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24-141


Display fields

1 2 3 4
Display group 70: EVAP canister purge regulator valve
Display xxx % xx.x % xx.xx g/s Test OFF/Test
ON
EVAP OK
EVAP notOK
Indicated EVAP canister purge regulator
valve duty cycle during diagnosis Oxygen sensor deviation
during diagnosis Idle Air Control (IAC) valve
deviation during diagnosis Diagnosis
condition
Diagnosis
results
Range 0-100 % -25.0 to 25.0 % -2.70 to 4.16 g/s ---
Specified
value 0-100 % - 5.4 to 9.4 % 0.00-0.33 g/s EVAP OK If "EVAP notOK" is indicated in display field 4:

- Check for blockage or leaks Page 24
-142
.
If "EVAP OK" is indicated in display field 4:

-
Press button to advance program
sequence.
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Rapid data transfer
HELP
Selecting function XX

Indicated on display
- Press buttons -0- and -6- to select "End Output" function 06, and
press -Q- button to confirm input.
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porative Emissions
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24-142

Checking for blockage and leaks
The EVAP canister purge regulator valve is
closed when power is off.

- Remove EVAP canister purge regulator valve -
N80- (component locations Page 24
-1 )

- Connect removed valve to harness connector.

- Start output Diagnostic Test Mode (DTM) and
select -N80- Page 01
-42
.

- Blow into long connection during output DTM,
and check whether valve opens and closes
properly. Replace valve if necessary.

- If valve is OK, check all hose connections
between tank and valve for blockage or leaks.

EVAP canister purge regulator valve -N80-
electrical test

- Disconnect harness connector from EVAP
canister purge regulator valve.

- Connect multimeter US 1119 (Fluke 83 or equivalent) and check
resistance at across valve terminals.
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porative Emissions
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If resistance is NOT OK:
Specified value: 22-30 - Replace EVAP canister purge regulator valve
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porative Emissions
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