Volkswagen Golf / Golf GTI / Jetta. Manual — part 216

24-118

Note:

All functions which could previously
be performed with VAG 1551/1552
can also be performed with the VAS
5051.

Checking function

VAG 1390 Hand vacuum pump

- Start engine and run at idle

speed.

Actuator (vacuum unit) on intake

manifold holds change-over barrel
in position for long intake channel.

- Have a second person press

accelerator pedal down fully onto
limit stop (throttle burst). Observe
vacuum unit for Intake Manifold
Change-Over Valve -N156-
(location: on left of intake
manifold).

Actuating element must rotate

barrel in intake manifold (arrow).

- Switch off ignition.

Components, checking

24-119

If the actuating element does not perform the
change-over sequence:

- Check activation of Intake Manifold Change

Over Valve -N156- via Output Diagnosis Test
Mode (DTM)

Page 01-100

.

If activation is OK:

- Connect scan tool.

- Pull vacuum hose -1-off non-return valve

- Connect hand vacuum pump VAG 1390 to non

return valve -2-.

- Perform Output Diagnosis Test Mode (DTM)

again. When Intake Manifold Change-Over
Valve -N156- valve is activated, operate hand
pump uniformly.

Actuating element must switch back and forth

between both positions.

Components, checking

24-120

If the change-over does not function as

described:

- Check change-over mechanics for freedom of

movement. Move rods by hand.

- Check vacuum pipes for correct connection.

- Check vacuum system including vacuum

reservoir.

Note:

The vacuum reservoir is bolted below the intake

manifold.

Components, checking

24-121

Intake Air system, leak testing

Checking with engine leak detector spray G
001 800 A1

Note:

The vacuum in the intake system will cause the

leak detector spray to be drawn in with the
unmetered air. The leak detector spray reduces
the ignitability of the mixture. This leads to a
drop in engine speed and to a change of
Oxygen Sensor (O2S) reading.

The safety precautions listed on the container

must be adhered to.

Special tools, materials and equipment

Note:

All functions which could previously be performed
with VAG 1551/1552 can also be performed with
the VAS 5051.

VAG 1551 Scan tool (or VAG 1552) with VAG

1551/3 adapter cable

Engine leak detector spray G 001 800 A1

Components, checking