Checking air flow meter potentiometer -G19 — AUDI

Special tools and workshop equipment required

Hose clamps 3094
V.A.G 1501
V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598 A
V.A.G 1598/3
V.A.G 1767 or V.A.G 1367 with V.A.G 1367/8

V.A.G 1551 with V.A.G 1551/1

Fitting location => Fitting locations overview, Page
25-5

Notes:

Carry out this check if flash code "2232" is displayed when fault memory is interrogated.
Air flow meter potentiometer -G19 can only be replaced together with air flow meter.

Test requirements:

Coolant temperature at least 85 °C.
No faults stored in fault memory
Final control diagnosis has been performed
Air conditioning switched off.
Cap on oil filler neck tight.
Dipstick fully inserted.
Electrical consumers switched off (radiator fan must not run during the test).
Ignition point and CO content OK.

Test sequence

Detach connector from potentiometer.

Connect multimeter as follows to measure voltage.

Connector / Contact · Measure to
3 · Battery positive

Specification: approx. battery voltage

If specification is not attained:

Eliminate open circuit or short circuit using the current flow diagram.

If the wiring is OK:

Connect multimeter between contacts 1 and 3 to measure voltage.
Switch the ignition on.
Specification: 4.35...5.35 V

Read supply voltage (U1) off multimeter and note value.

If specification is not attained:

With the ignition switched off, use adapter V.A.G 1598/3 to connect test box V.A.G 1598 A only to connector of KE III Jetronic control unit (control unit remains disconnected) => Page
25-16
.

Check for open circuit and short to positive or earth in the following wiring connection:

Connector / Contact · Test box V.A.G 1598 A / Socket
1 · 26
2 · 23

Rectify any open/short circuit as necessary.

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

If no wiring fault is detected:

Connect test lead V.A.G 1501 between air flow meter potentiometer and connector.
Connect multimeter between contact 2 and 3 of test lead V.A.G 1501 to measure voltage.

Switch the ignition on, baffle plate in rest position.
Specification: 0...200 mV

Note:

Maximum adjustment range: From displayed value up to max. 200 mV.

Connect ignition tester V.A.G 1767 (or V.A.G 1367) with ignition switched off:

=> Operating Instructions

Notes:

The TDC sender of ignition tester V.A.G 1367 must be inserted into the gearbox housing as far as the stop.
The ignition point is indicated directly on V.A.G 1767 (or V.A.G1367). It is not necessary to use a strobe light aimed at the timing notches.
Incorrect measurements may occur with ignition tester V.A.G 1767 if triggering probe is slightly open (e.g. excessive tension on helical cable).

Start engine and run at idling speed.
Connect fault reader V.A.G 1551 => Page
01-4
.

Flash code output
with the ⇒ key
Indicated on display

Press the ⇒ key on V.A.G 1551 until "permanent earth connection on initiating line" appears on display.

Permanent earth connection on initiating line
Indicated on display

Note:

A constant ignition point from VEZ control unit is only applied 4 seconds after pressing ⇒ key on V.A.G 1551.

Detach rubber retainer of idling stabilisation valve -N71 from retaining bracket -2-.
Pull idling stabilisation valve -N71 slightly forward and disconnect connector.

Note:

Idling speed increases slightly after disconnecting connector.

Increase speed until following values are obtained:
Specification, idling speed: 800 ±20 rpm
Specification, ignition point: 13...17°before TDC

Read output voltage (U2) off multimeter and note down value.

U1 -
Supply voltage
between contact 1 + 3
U2 -
Output voltage at idling speed
between contact 2 + 3

Compare output voltage (U2) allowing for supply voltage (U1).

If, at an idling speed of 800 ± 20 rpm, the measured output voltage is at or slightly outside of lower tolerance range:

Check for leaks (unmetered air) in intake air system => Page
25-87
.
Repeat test after eliminating leaks.

If no leaks are detected:

Re-adjust potentiometer with trim screw.

Re-adjusting potentiometer with trim screw

Switch ignition off.
Disconnect test lead V.A.G 1501 on potentiometer.
Carefully remove sealing compound over trim screw -arrow-.
Reconnect test lead V.A.G 1501 to potentiometer.
Connect multimeter between contact 2 and 3 of test lead V.A.G 1501 to measure voltage.

Rubber retainer of idling stabilisation valve -N71 pulled off retaining bracket -2-.
Idling stabilisation valve -N71 pulled slightly forward and connector disconnected.

Start engine and run at idling speed.
Increase speed until following value is obtained:
Specification, idling speed: 800 ±20 rpm

Turn trim screw on potentiometer so that output voltage (U2) lies at centre of tolerance range, allowing for supply voltage (U1).

If tolerance range is not attained:

Unscrew fuel distributor from air flow meter and replace air flow meter with potentiometer.

Note:

After air flow meter has been replaced with potentiometer, adjustment of potentiometer is not necessary.

If tolerance range is attained:

Secure trim screw with locking paint.
Switch off ignition in order to erase fault memory.