Servicing intake manifold flap: Audi 1.9 TDI (ASZ, ATD, AXR)

ATD AXR
The intake manifold flap is closed for approx. 3 seconds when stopping engine and then opens again. This reduces the stop jolt.

From charge air cooler
10 Nm
Intake connecting flange
With exhaust gas recirculation valve and intake manifold flap

Mechanical exhaust gas recirculation valve
O-ring
Renew

Intake manifold

Gasket
Renew

Connecting pipe
To exhaust manifold

25 Nm
Vacuum supply
From vacuum pump

Intake manifold flap change-over valve -N239
Checking => Page 23-18

Vacuum control element
Bracket
10 Nm

Testing change-over function of intake manifold flap

Special tools and workshop equipment required

V.A.G 1390
V.A.G 1526 A
V.A.G 1527 B
V.A.G 1594 A
V.A.G 1598/31

Checking function

Start engine and run at idling speed.
Switch off ignition.
Observe positioning lever on intake manifold flap (2nd person required).
After switching off the ignition, the intake manifold flap should close and open again after approx. 3 seconds.

If change-over does not occur, the following checks must be carried out.

Check intake manifold flap change-over mechanics for freedom of movement. To do this operate rods by hand.
Check function of vacuum positioning element with hand vacuum pump V.A.G 1390.
Check vacuum pipes for correct connection.

If no fault is found in the mechanical components:

Unplug connector on intake manifold flap change-over valve -N239 -item 2-.

Testing internal resistance

Connect multimeter (resistance measurement range) between contacts 1 and 2.
Specification: 25 ... 45 ω

If the specification is not obtained:

Renew intake manifold flap change-over valve.

Checking voltage supply

Test requirement:

Fuse for intake manifold flap change-over valve OK

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

Diesel direct injection relay OK; Test=>Page 23-69.

Connect multimeter (voltage measurement range) as follows:

Connector / Contact · Measure against
1 · Engine earth

Switch on ignition.
Specification: approx. battery voltage

If the specification is not obtained:

Test wiring for open circuits and rectify if necessary.

Checking activation

Connect voltage tester V.A.G 1527 B between contacts 1 and 2
Start final control diagnosis and select intake manifold flap change-over valve -N239 =>Page 01-52.
The LED should flash slowly.

Note:

The LEDs on voltage testers with a low current draw continue to glow faintly between impulses from the engine control unit (rather than going out completely) and become much brighter when receiving an impulse.

Press the ◂button to exit from function "03 - Final control diagnosis".
Select diagnosis function "06 - End output".
Switch off ignition.

If the LED does not react as described:

Connect test box V.A.G 1598/31 to wiring harness for engine control unit.Do notconnect to the engine control unit itself.
Connecting test box to engine control unit without protective covering=>Page 23-49.
Connecting test box to engine control unit with protective covering=>Page 23-51.

Test for open circuit and short to positive or earth in the following wiring connections:

Connector / Contact · Test box V.A.G 1598/31 / Socket
2 · 81

Rectify any open/short circuit as necessary.

If no fault is found:

Fit a new engine control unit.
Removing and installing engine control unit without protective housing=>Page 23-57.
Removing and installing engine control unit with protective housing=>Page 23-60.