Audi Workshop Service and Repair Manuals

Test condition

• ● Fuel pressure OK

Removing fuel rail

• ‒ Remove engine compartment cover.
• ‒ Remove connecting pipe between air cleaner housing and throttle valve unit.
• ‒ Disconnect vacuum hose from fuel pressure regulator.
• ‒ Unplug connectors from injectors and remove cable ties if necessary.
• ‒ Unscrew fuel rail from intake manifold and lift off intake manifold with injectors.

Checking injectors for leaks

• ‒ → Hold injector to be tested over graduated beaker of injection quantity tester V.A.G 1602.
• ‒ Connect up test box V.A.G 1598/31 at wiring harness to engine control unit. Actual engine control unit is not to be connected.
• ‒ Use wires from adapter set V.A.G 1594 A to jumper contacts 1 and 65 at test box (this step connects earth to one end of fuel pump relay coil).
• ‒ Switch on ignition.

Note:

After switching on ignition, fuel pump runs continuously, even if engine is not running. Reason: Fuel pump relay receives positive supply via central electrics unit after switching on ignition. Earth is applied to fuel pump relay via cable link in test box.

• ‒ Check injectors for leaks (visual inspection). With fuel pump running, only 1...2 drops per minute per injector may emerge.
• ‒ In the event of greater fuel loss, shut off fuel pump (switch off ignition) and replace defective injector.

Checking injection quantity

• ‒ Hold injector to be tested over graduated beaker of injection quantity tester V.A.G 1602.

• ‒ → Connect one contact of injector to engine earth using test lead and crocodile clamp from V.A.G 1594 A.
• ‒ Connect second contact of injector to positive with remote control V.A.G 1348/3A, adapter lead V.A.G 1348/3-2 and test lead.
• ‒ Use leads from adapter set V.A.G 1594 A to jumper contacts 1 and 65 at test box.
• ‒ Switch on ignition.
• ‒ Fuel pump must run
• ‒ Operate remote control V.A.G 1348/3A for 30 seconds.
• ‒ Perform measurement with all injectors.
• ‒ Once all four injectors have been actuated, place graduated beakers on a flat surface.

Specification for each injector: 105 ... 125 ml

If reading does not match specification for all injectors:

• ‒ Check fuel pressure .

If reading does not match specification for one injector:

• ‒ Replace appropriate injector.

Note:

Spray pattern is also to be checked when checking injection quantity. It must be the same for all injectors.

Fuel rail with injectors is to be installed appropriately in reverse order of removal paying attention to the following:

• ● Replace O-rings at all joints opened (to replace front O-ring, never pull plastic cap off valve head - lift O-ring over plastic cap).
• ● Moisten O-rings with fresh engine oil.
• ● Make sure clips are properly connected.
• ● Apply tightening torque of 10 Nm when screwing fuel rail to intake manifold.