Audi Workshop Service and Repair Manuals

Note:

Defective injectors cause the following faults:

• ◆ Loss of power
• ◆ Excessive black exhaust smoke
• ◆ Excessive blue smoke when starting from cold
• ◆ Higher fuel consumption
• ◆ Engine over-heating
• ◆ Knocking in one or more cylinders
• ◆ Misfiring

Removing injectors

• ‒ Remove injection pipes with open ring spanner 3035.

Note:

Always remove pipe set complete. Do not alter pipe shape.

• ‒ Remove securing nut, take off retainer and take out injector.

If the injectors are seized, construct the following auxiliary tool:

• ‒ Saw off an injection pipe about 5 cm away from the injector union nut.
• ‒ Braze an M6 nut onto the sawn-off end of the pipe section.
• ‒ Clean the auxiliary tool thoroughly. Any dirt will make the injector unusable.
• ‒ → Screw the union nut end of the auxiliary tool to the seized injector, then apply special tool 3364 to the end with the brazed-on nut.

Installing injectors

Note:

Always renew copper seals between cylinder head and injectors.

• ‒ Insert injectors.
• ‒ Check mounting is seated correctly in cylinder head.
• ‒ Fit retainer.

Tightening torques:

• Injection pipes: 25 Nm
• Bolt for retainer: 20 Nm

Testing injectors

• Specification: -1.50 mg/H...+1.50 mg/H (milligrams per stroke)

• ‒ If one or more of the values is outside the tolerance, swap round the injectors (except the injector for cylinder 3).
• ‒ If the fault moves along with the injector, fit a new injector.
• ‒ If the fault remains on the same cylinder, swap round the pressure valves.
• ‒ If the fault moves with the pressure valve, fit a new pressure valve with oil seal
  =>Servicing injection pump - Page 23-9.

Notes:

• ◆ When removing the sealing ring from the pump, always use a soft object (plastic or wood) in order not to scratch the sealing surface.
• ◆ After 15,000 km the pressure valves must always be renewed as a complete set.

• ‒ If the fault remains on the same cylinder, check the compression.

This engine is equipped with dual spring injectors. The fuel injected therefore occurs in 2 stages.
If faults occur with these injectors then they are to be exchanged as neither servicing nor pressure setting is possible.

→ Test injectors using V.A.G 1322 and pressure pipe V.A.G 1322/2.

• ● Pressure gauge on

• ‒ Move pump lever down slowly. When injection begins, read off spray pressure. If the pressure does not match the specification, fit a new injector.

Engine code: AFF, AHU, AFN, AVG

Engine code: AHH

Checking for leaks

• ● Pressure gauge on

• ‒ Move pump lever down slowly and maintain a pressure of approx. 150 bar for 10 seconds. No fuel should leak from the nozzle tip.
• ‒ If injector leaks, replace.