Checking air mass meter -G70 — AUDI

AQF AQH ARU AKC AUW AVN AVP
Test conditions

Coolant temperature at least 80 °C.
Electrical consumers switched off (radiator fan must not run during the check)
Air conditioner switched off
Fuse for air mass meter OK

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Checking function

Connect the vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and select engine electronics control unit 1 with "Address word" 01 => Page
01-15
.
For this purpose, the engine must be running at idling speed.

Rapid data transfer
HELP
Select function XX
Indicated on display:

Press keys 0 and 4 for the function "Initiate basic setting" and confirm entry with Q key.

Note:

During basic setting, the solenoid valve for the activated charcoal filter (ACF valve -N80) is closed and the air conditioning compressor is switched off by the engine control unit.

Basic setting
Q
Enter display group number
XXX
Indicated on display:

Press keys 0, 0 and 2 for "display group number 2" and confirm entry with Q key.

System in basic setting 2
⇒
1
2
3
4
Indicated on display:

Check specified results for recorded load.

Display zones
1 · 2 · 3 · 4
Display group 2: Intake air mass at idle and operating temperature
Display · xxx rpm · xx.x % · x.x ms · xxx.x g/s
Display · Engine speed / (in steps of 40 rpm) · Load · Average injection period · Air mass
Range · min.: 550 rpm / max.: 7200 rpm · min.: 0 % / max.: 110 %
Specified value · 600...820 rpm · 14.0...24.0 % · 1.0...5.0 ms · 3.5...7.0 g/s
Note · --- · --- · If specified value is not attained: Evaluation, display zone 3 / =>Page . 24-68 · If specified value is not attained: Evaluation, display zone 4 / =>Page . 24-69

If specified value is attained:

Press ⇒key.
Press keys 0 and 6 for the "End output" function and press the Q key to confirm entry.
Switch ignition off.

Evaluation of display group 002

Display zone: 3 · Possible causes of fault · Fault remedy
Less than 1.0 ms · - Lower values can only occur when vehicle is on overrun
Greater than 5.0 ms · - Engine load from ancillaries · - Eliminate load (air conditioner system/ power steering/alternator)
- Poor idling (not running on all cylinders) · - Test spark plugs / Check injectors =>Page 24-48
- Throttle valve control part -J338 defective · - Check throttle valve control part =>Page . 24-168

Evaluation of display group 002

Display zone: 4 · Possible causes of fault · Fault remedy
Less than 3.5 g/s · - Large quantity of unmetered air between intake manifold and air mass meter / - Voltage supply to air mass meter or wiring to engine control unit · - Test for leaks (unmetered air) in intake air system => Page 24-70
Greater than 7.0 g/s · - Engine load from ancillaries · - Eliminate load (air conditioner system/ power steering/alternator)
- Voltage supply to air mass meter or wiring to engine control unit · - Check voltage supply and/or wiring => Page 24-70

Testing voltage supply to air mass meter

Detach connector from air mass meter.
Connect hand-held multimeter for voltage measuring to socket 2 of connector and engine earth.
Operate the starter briefly.

Specified value: approx. battery voltage

Note:

Voltage supply to air mass meter is from fuel pump relay.

If battery voltage is not present.

Test wiring from socket 2 on connector via fuse to fuel pump relay for open circuit or short to earth. Rectify, if necessary.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

If the specified value is achieved.

Check earth connection to engine control unit => Page
24-71
.

Checking earth connection

Connect hand-held multimeter for voltage measuring to sockets 2 and 3 of the connector.
Operate the starter briefly.

Specified value: approx. battery voltage

Note:

Engine control unit earth is present at socket 3 of the connector.

If specified value is not attained:

Check the wiring connections
=>Page
24-72
.

Connect hand-held multimeter for voltage measuring to sockets 3 and 4 of the connector.
Switch the ignition on.

Specified value: approx. 5 V.

If specified value is not attained:

Check the wiring connections
=>Page
24-72
.

Checking wiring to air mass meter

Note:

The signal wire is also checked during the wiring check.

Connect test box V.A.G 1598/31 to wiring harness for engine control unit; the engine control unit must not be connected => Page
24-12
.
Check for open circuit and short to positive or earth in the following wiring connections:

Connector for air mass meter -G70, socket · Test box V.A.G 1598/31 socket
3 · 27
4 · 53
5 (signal wire) · 29

Wire resistance: max. 1.5 Ohm

Rectify any open/short circuit as necessary.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Additionally check all wires for short to one another.

Connector for air mass meter -G70, socket · Test box V.A.G 1598/31 socket
3 · 53 and 29
4 · 27 and 29
5 (signal wire) · 27 and 53

Specified value: infinite resistance (no continuity)

If the voltage supply and the wiring are OK, renew the air mass meter -G70.