1997 AUDI TT start

24-1


Motronic fuel injection
system, servicing

Safety precautions

If special testing equipment is required during
road test, note the following:

WARNING!

Test equipment must always be secured to
the rear seat and operated from there by a
second person.
If test and measuring equipment is operated
from the passenger seat, the person seated
there could be injured in the event of an
accident involving deployment of the
passenger-side airbag.
To reduce the risk of personal injury and/or
damage to the fuel injection and ignition system,
always observe the following:
Only disconnect and reconnect wires for
injection and ignition system, including test
leads, when ignition is turned off.
If engine is to be cranked at starting RPM
without starting (e.g. for compression testing),
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Note:

Idle speed cannot be adjusted.
Idle speed is checked during basic setting of
the engine.
During basic setting, the Evaporative Emission
(EVAP) canister purge regulator valve (EVAP
valve -N80-) is closed and the A/C compressor
is switched off

Test sequence

- Check DTC memory Page 01
-16
. There must
not be any DTCs stored, repair malfunctions if
necessary, erase DTC memory, switch engine
off and start again, road test vehicle and check
DTC memory again as a control measure.

- Let engine continue to run at idle.

WARNING!

The electric fan for the radiator must not be
running. Rapid data transfer
HELP
Select function XX

When indicated on display
-
Press buttons -0- and -4- to select "Initiate basic setting" and press -Q-
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24-35


- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Measure fuel pressure.

Specification: about 3.5 bar positive pressure

- Disconnect vacuum hose at fuel pressure regulator.

Fuel pressure must rise to about 4.0 bar positive pressure.
- Switch ignition off.
- Check for proper seal and residual pressure by observing pressure
drop on pressure gauge.
After 10 minutes, there must be at least 2.5 bar positive pressure
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If residual pressure sinks below 2.5 bar positive
pressure:

- Start engine and let run at idle.

If pressure does not drop now:
If pressure drops again:
If pressure does not drop now: - Wait until pressure has dropped, and then switch off ignition.
Simultaneously close shut-off valve of VAG1318 pressure gauge (lever
perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.
- Test check-valve on Fuel Pump (FP).
- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Wait until pressure has dropped, and then switch off ignition.
Simultaneously clamp return line (with blue marking) completely
closed.
- Replace fuel pressure regulator
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- Repair open circuit if necessary.
If LED lights up:

- Activation of fuel injectors, checking

Checking activation

Test requirement:

Internal resistance of valve OK

- Slide back rubber grommet of fuel injector
connector, but leave connector connected.

Note:
Voltage testers do not go out completely during low current pick-up
between activations by the ECM, but rather continue to glow a little and
then get slightly brighter during activation. - Connect VAG1527B voltage tester between sockets 2 (signal) and 1
(B+).
- Operate starter briefly (engine can also start).

LED must blink.
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- Operate starter briefly (engine can also start).

Specification: approx. battery voltage
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24-65
If specified value is not obtained:

- Check wire connection from terminal 2 of
connector to Fuel Pump (FP) relay via fuse for
open circuit and short circuit to Ground (GND):

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit or short circuit if
necessary.

Note:
Ground (GND) from the ECM is present at terminal 3 of connector.
If specified value is not obtained: - Connect multimeter to terminal 2 and terminal 3 of connector for
voltage measurement.
- Operate starter briefly (engine can also start).

Specification: approx. battery voltage
- Check wire connections Page 24
-67
.
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pair&id=AUDI.B5.FU06.24.1