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Testing the intake system for tightness (unmetered air) > < Test fuel pump relay and control

Octavia Mk1

Test air mass meter G70
Test air mass meter -G70-
Special tools and workshop equipment required
t  Vehicle system tester V.A G 1552 with cable -V.A.G 1551/3-
t  Handheld multimeter, e.g. -V.A.G 1526 A -
t  Voltage tester, e.g. - V.A.G 1527-
t  Measuring tool set -V.A.G 1594 A -
t  Test box -V.A.G 1598/22-
Check for proper operation
Test conditions
   
l  Fuse no. 43 o.k.
l  Coolant temperature at least 80°C.
l  All electrical consumers, e.g. lights and rear window heater, must be switched off.
l  If vehicle is equipped with air conditioning, this must be switched off.
l  On vehicles with automatic gearbox the selector lever must be in position “P” or “N”.
l  Vehicle standing, engine idling
–  Select 08 for the function “read measured value block” and further select display group 001.
  S97-0319
The following appears in the display:
–  In display field 2 check whether the coolant temperature is above 80°C.
–  Change to the display group 2 by pressing the ↑ button.
  
Reading measured value block 1                      ->
850/rpm    90°C    0.80 V   0000010
The following appears in the display:
The drawn in air mass is displayed in the display field 2 (Milligram per stroke).
Specified value: 76 up to 164 mg/s
–  If the specified values are not reached or if a fault regarding the air mass meter is stored in the fault memory, check the voltage supply of the air mass meter → Anchor or → Anchor.
Check the voltage supply of the air mass meter on vehicles ► 07.97.
  
Reading measured value block 2                      ->
850/rpm    120 mg/s    0 km/s   0100
–  Disconnect the plug from the air mass meter -G70- and connect the multimeter between contact 3 of the plug and the engine mass.
–  Start engine and run in idle.
Specified value: 11...15 V
–  Switch off ignition.
–  If the voltage supply is o.k., check signal lines and earth connection → Anchor.
If no voltage is present:
–  Check the cable connection from contact 3 of the plug to fuse no. 43 for continuity and/or short-circuit to earth, if necessary repair cable connection → Current flow diagrams and Fitting locations.
–  If fuse and wiring are o.k. but neverthless no voltage is present, check the fuel pump relay → Chapter.
Check the signal line and the earth connection of the air mass meter on vehicles ► 07.97.
–  Connect the test box -V.A.G 1598/22- to the wiring loom of the engine control unit → Chapter.
–  Test wiring from plug of air mass meter to engine control unit for interruption or short-circuit to positive or earth.
  S24-0211
Plug of air mass meter G70 Test box - V.A.G 1598/22-
113
212

–  If the wiring is O.K., replace air mass meter -G70-.
Check the voltage supply of the air mass meter on vehicles 08.97 ►
   
–  Disconnect the plug -1- from the air mass meter -2- and connect the hand-held multimeter between contact 3 of the plug and the engine mass.
–  Start engine and run in idle.
Specified value: 11...15 V
–  Switch off ignition.
–  If the voltage supply is o.k., check signal lines and earth connection → Anchor.
If no voltage is present:
–  Check the cable connection from contact 3 of the plug to fuse no. 43 for continuity and/or short-circuit to earth, if necessary repair cable connection → Current flow diagrams and Fitting locations.
–  If fuse and wiring are o.k. but neverthless no voltage is present, check the fuel pump relay → Chapter.
Check signal line and earth connection on vehicles 08.97 ►
–  Connect the test box -V.A.G 1598/22- to the wiring loom of the engine control unit → Chapter.
  N24-0701
–  Check wiring between the test box and the 4-pin plug for continuity according to current flow diagram, cable resistance: max. 1.5 Ω.
  N24-0701
Plug of air mass meter G70 Test box - V.A.G 1598/22-
113
212

–  Additionally test all wiring to each other for short-circuit.
Specified value: ∞ Ω
If the lines are not found to be faulty:
–  Replace air mass meter -G70- with intake air temperature sender -G42- → Chapter.
   

Testing the intake system for tightness (unmetered air) > < Test fuel pump relay and control