check oil AUDI A4 1999 B5 / 1.G AHA Engine Intake Manifold Tuning System Workshop Manual

24-155

Intake Manifold Tuning (IMT) function,
checking


Note:
The following test should only be conducted if
performance deficiencies occur.

- Increase engine rpm clearly above 4500 RPM.

Intake manifold tuning vacuum solenoid must be
actuated (solenoid is located on intake manifold,
left-front, under the ignition coils).
If the vacuum solenoid is not actuated:

- Check intake manifold tuning valve -N156-
(change-over valve) page 24
-156
.

- Check vacuum system for leaks page 24
-
162
.

- Check that vacuum lines are correctly installed,
do not leak and are not blocked.

- Check change-over mechanism for ease of
movement (activate change-over linkage by
hand).
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