AUDI A4 1995 B5 / 1.G AFC Engine Intake Manifold Change Over Checking Workshop Manual

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Intake manifold change-over,
checking
Carry out this check only if complaints of "vehicle
under-powered" are received.
Intake manifold change-over from the "long" to
"short" intake path occurs at approx. 4000 RPM.

Checking function

- Raise engine speed above 4000 RPM.

Vacuum canister for intake manifold change-
over valve (on intake manifold, left rear)
must tighten.
If canister does not tighten:

- Check intake manifold change-over valve using
output Diagnostic Test Mode page 01
-145
,.

If necessary check valve and triggering page
24
-64
.

- Check vacuum reservoir for leaks page 24
-
111
.

-
Check vacuum lines for correct routing, leakage
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and flow (blockage) page 24
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.

- Actuate change-over linkage by hand to check
change-over system mechanical components for
ease of movement.
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Checking vacuum system

- Start engine and let idle for two to three minutes
to build up vacuum.

- Switch ignition OFF.

- Disconnect 2-pin harness connector from intake
manifold change-over valve.

If the vacuum canister returns to its original position, check as follows: - Using jumper wires from connector test kit VW 1594:
- Connect either connector terminal to intake manifold Ground (GND)
point.
- Connect remaining terminal to VAG1348/3A remote control.
- Connect VAG1348/3-2 adapter wire to B+.
- Activate remote for approx. 2 to 3 minutes, during which time vacuum
canister must remain connected.
- Switch ignition OFF.
- Disconnect vacuum lines from intake manifold change-over vacuum
canister.
- Connect US 8026 hand pump to vacuum canister.
- Operate hand pump and note change-over operation.
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- Check vacuum canister for leaks

Vacuum canister should tighten and not
return to its original position until the vacuum
is released at the hand pump
If vacuum canister returns to its original position
(while vacuum is applied):

- Replace intake manifold change-over canister.
If vacuum canister does not tighten, check intake
manifold change-over valve for continuity as
follows:

- Using jumper wires from connector test kit VW
1594:

If no malfunction was found during these checks: - Connect either of valve terminals to intake manifold Ground (GND)
connection.
- Connect remaining terminal to VAG1348/3A remote control.
- Connect VAG1348/3-2 adapter wire to B+.
- Operate VAG1348/3A remote control.
- Check valve for flow (remove vacuum lines and blow through them).
- If necessary, replace intake manifold change-over valve.
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- Check vacuum system for leakage page 24
-111
.
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