Removing, installing and testing injectors and constant pressure valves — AUDI

AHU
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

Defective constant pressure valves cause the following fault:

Uneven idling, possibly at irregular intervals (sporadically)

Special tools, testers and auxiliary items

Ring spanner 3035
Injector tester V.A.G 1322
Pressure pipe V.A.G 1322/2
Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/1

Removing

Unscrew injection pipes using 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.

Note:

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 onto the seized injector, then apply special tool 3364 to the end with the brazed-on nut.

Installing

Note:

Always renew copper seals between cylinder head and injectors.

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

Tightening torques

Component · Nm
Injection pipes · 25
Nut for retainer · 20

Testing

Connect fault reader V.A.G 1551 and select engine electronics control unit => Page
01-2
.
Read measured value block 13
⇒
0.82mg/H
-0.12mg/H
0.49mg/H
Read measured value block, Display Group 013, engine at idling speed => Page
01-76
.
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, check the compression.

=> 4-cyl. diesel direct injection engine (TDI), Mechanics; Repair group 15; Removing and installing cylinder head; Testing compression
4-cyl. diesel direct injection engine (TDI), Mechanics
Removing and installing cylinder head
Testing compression

If the compression is OK, renew the relevant constant pressure valve -arrow- together with sealing ring.
Tightening torque: 45 Nm

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 constant pressure valves must always be renewed as a complete set if one or more of them is defective.

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.

Warning!
When testing injectors ensure that the jet of fuel does not contact the hands as the high pressure will cause the fuel to penetrate the skin and may cause severe injuries.
Testing spray pressure

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.

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

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.