lock AUDI A4 1999 B5 / 1.G APB Engine Motronic Multiport Fuel Injection System Servising Workshop Manual

24-36

- When the vacuum hose is re-connected the fuel
pressure should drop by around 0.5 bar.

If the pressure does not change as specified,
carry out the following tests:


Check vacuum hose for cracks and other
damage.

Test vacuum hose for blockages at intake
manifold. To do this, disconnect hose at fuel
pressure regulator and blow into it.

- If there are no leaks and no blockages in the
vacuum hose, install new fuel pressure
regulator.

- Replace hose clamp that secures vacuum hose
to the fuel pressure regulator and make sure
that new clamp is properly installed.

Checking residual fuel pressure

- Residual pressure 10 minutes after switching off
engine (minimum pressure)

With engine cold: at least 2.2 bar
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24-61

Note:
Read measuring value block display group 2 as
described in repair manual and evaluate it
Page 24
-69
. If the suggested repair steps refer
to the voltage supply test for the Mass Air Flow
(MAF) sensor or the wiring connections from the
Mass Air Flow (MAF) sensor to the Engine
Control Module (ECM), proceed to the following
pages.
Please note the distinction between sensors
made by Bosch and those made by Hitachi
(recognizable via the writing on the sensor).

Voltage supply for Mass Air Flow (MAF)
sensor, checking (Hitachi MAF sensor)

Note: For Bosch Mass Air Flow (MAF)
sensors see page Page 24
-65
.

- Disconnect connector from Mass Air Flow (MAF) sensor.
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Rapid data transmission
HELP
Select function XX

Indicated on display:
- Press buttons -0- and -8- to select function "Read Measuring Value
Block" and confirm entry with -Q- button.
Read Measurin
g Value Block
Enter display group number XXX

Indicated on display:
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jection
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24-77

- Press buttons -0-, -0- and -1- to select "Display
Group 01" and confirm entry by pressing -Q-
button. Read Measuring Value Block 1
1
2
3
4

Indicated on display: (1...4 Display fields)
If the engine speed does not change: - Note engine speed in display field 1.
- Systematically spray parts of intake system with engine leak detection
spray.
-
Press button.- Press buttons -0- and -6- to select function "End Output" and confirm
entry with -Q- button.
Pa
ge 89 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
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11/22/2002 htt
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play?action=Goto&t
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pair&id=AUDI.B5.FU04.24.1