Removing, installing and testing injectors — AUDI

AFN AHH AHU
Note:

Defective injectors cause the following faults:

Loss of power
Excessive black exhaust smoke
Excessive blue smoke when starting from cold
High fuel consumption
Engine overheating
Knocking in one or more cylinders
Misfiring

Removing the injectors

Remove injection pipes using open ring spanner 3035.

Note:

Always complete remove pipe set. 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 render 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 soldered-on nut.

Installing the injectors

Note:

Always renew copper seals between cylinder head and injectors.

Insert the injectors.
Check mounting bracket is seated correctly in the cylinder head.
Fit the retainer.

Tightening torque:

Injection pipes: 25 Nm
Retainer clip nut: 20 Nm

Checking the injectors

Read measured value block
13
⇒
0.82 mg/stroke 0.12 mg/stroke 0.49 mg/stroke
Read measured value block, display group 13, engine at idling speed => Page
01-74

Specified value: -1.50 mg/stroke +1.50 mg/stroke (milligrams per stroke)

If one or more of the specified values is out of range, swap round the injectors (except the injector for No. 3 cylinder).
If the fault moves along with the injector, fit a new injector.
If the fault remains on the same cylinder, swap round the constant pressure valves.
If the fault moves with the constant pressure valve, replace the pressure valve and oil seal=>Repair 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 complete set of pressure valves must always be replaced.

If the fault remains on the cylinder, check the compression.

This engine is equipped with dual spring injectors. The fuel injection therefore takes place in 2 stages.
If faults occur in these injectors they must be replaced, since neither repair nor pressure setting is possible.

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

Important:
When testing injectors, care should be taken to ensure that the jet of fuel does not come into contact with the hands, as the high pressure will cause the fuel to penetrate the skin and it could cause severe injuries.
Pressure gauge on

Slowly depress the pump lever. When injection begins, read off spray pressure. If the pressure does not match the specified value, fit a new injector.

Engine codes: AFF, AHU, AFN

New injectors · 190 ... 200 bar
Wear limit · 170 bar

Engine codes: AHH

New injectors · 220 ... 230 bar
Wear limit · 200 bar

Testing 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 opening.
If injector leaks, replace.