Fuel Injector: Service and Repair
Fuel Injectors
Special tools, testers and auxiliary items required
• Socket 14 mm (3150)
• Torque Wrench (5-50 Nm) (V.A.G 1331)
• Ratchet, Reversible (V.A.G 1331/1)
• Puller (T10055) with Adapter (T10055/1)
• Socket (T40055)
• Tool Insert AF 19 (V.A.G 1331/5)
Removing
CAUTION!
Follow the guidelines for clean working conditions when working on the fuel system. Refer to => [ Clean Working Conditions and Fuel System Work Instructions ] Clean Working Conditions and Fuel System Work Instructions.
Always follow these instructions before and during work.
When replacing an injector, the adaptation value for the new injector must be programmed into the Engine Control Module (ECM). Refer to => [ Engine Control Module Functions and Components, Adapting ] Programming and Relearning.
• The illustration shows the removal and installation of the injectors for cylinder bank 2. The procedure for cylinder bank 1 is almost identical, except for a few steps that are omitted.
- Remove the engine cover.
CAUTION!
Mark the allocation of the injectors to the cylinder.
Note the rules of cleanliness for working on the fuel injection system.
Always seal any open connections with a suitable cover.
• This step applies only to cylinder bank 1: Remove the upper air filter housing with the Mass Airflow (MAF) sensor. Refer to => [ Air Filter Housing Overview ] Description and Operation.
- Pull the release pins upward - arrow - and remove the return line connections from the injectors.
- Disconnect the connector on the injector to be removed.
- Loosen the union fittings for injector lines - 1, 6 and 7 - at the injectors using (T40055).
- Loosen the union fittings for injector lines - 1, 6 and 7 - at the fuel rail using (3150) or (V.A.G 1331/5).
- Remove the injector cover bolts - arrows -.
- Pull the covers upward and turn them 90° (1/4) additional turn.
- Remove the injector tensioning bracket nuts - arrows -.
- Remove the injectors using the (T10055) and (T10055/1).
- Place the injectors on a clean cloth.
Important Information on Installing the Fuel Injectors
• The following components, seals and O-rings must be replaced each time a fuel injector is removed, and installed or replaced: "copper washer", "O-ring for the fuel injector shaft" and the "O-ring for the fuel injector return"
• Replace the following components, seals and/or O-rings each time an injector is replaced: "tensioning bracket" "injection line" "copper washer" "injector shaft O-ring" and "injector return O-ring".
• When installing, the fuel injectors and injection lines may only be installed on the same cylinder as before.
• Check the fuel injectors and installation locations for contamination before assembling.
• The fuel injectors must not have any damage.
• Lubricate all of the O-rings with assembly oil or engine oil before installing.
If a Used Fuel Injector is Installed
- Spray the tip of the fuel injector with a rust removing spray. Remove the rust or oil particles with a rag after approximately 5 minutes.
- If an injector is very dirty, clean the tips of the injection around the copper sealing ring with a soft brush (do not let the brush come in contact with the holes for the jets).
- To remove the used copper sealing ring from the fuel injector, clamp the sealing ring carefully in a vise until the clamping jaws on the vise prevent the ring from turning. Pull the fuel injector out of the copper sealing ring by hand with slight twisting and pulling motions.
- Use a scraper to remove any deposits under the copper sealing ring.
- Install the new copper sealing ring with a plastic bushing.
- Check the O-ring for the fuel return connection at the injector for damage and deformation.
If there Identifiable O-ring Damage or Deformation
- Replace the O-ring for the fuel return connection. O-rings must be lubricate when installed.
- Lubricate the fuel return connection O-ring and the fuel return connection with assembly oil or clean engine oil.
- Carefully roll the new O-ring onto the fuel return connection. Check for correct seating.
Continued
- To remove rust particles on the fuel injector sealing surface, clean the fuel injector duct in the cylinder head with a cloth dampened with engine oil or rust remover. Do not damage the sealing flanges.
- Install the fuel injectors.
- First tighten the union fittings on the high pressure or injection lines by hand.
- Make sure the lines are seated correctly without tension.
- Tighten the high pressure lines, refer to one of the following:
14 mm wrench, refer to => [ Tightening the High
Pressure Line to the Fuel Rail with a 14 mm Wrench ] Cylinder Head Overview.
17 mm wrench, refer to => [ Tightening the High
Pressure Line to the Fuel Injector with a 17 mm Wrench ] Cylinder Head Overview.
19 mm wrench, refer to => [ Tightening the High
Pressure Line to the Fuel Rail with a 19 mm Wrench ] Cylinder Head Overview.
- Press the return line connections carefully over the copper sealing ring onto the injector (check the copper sealing ring first for damage). The connection must engage audibly. Then press the release pin down carefully.
The "injector quantity calibration" and the "injection pressure calibration" for the new injectors must be must be programmed into the ECM after replacing one or more injectors. Refer to => [ Engine Control Module Functions and Components, Adapting ] Programming and Relearning.
Check all the other injectors as well regarding their "injector quantity calibration" and "injection pressure calibration" to make sure all comparison values have been entered correctly. If the correct comparison value have been stored in the ECM, then these comparison value must never be reentered.
Fuel System, Bleeding and Performing a Leak Test
- Let the engine run a few minutes at idle and then turn it off.
- Turn off the ignition.
- Check the entire fuel system and the 6 return line connections for leaks.
If there are leaks despite correct tightening specifications, replace the affected component.
• The return lines may only be replaced completely with the pressure retention valve.
Observe the safety precautions that apply to road tests. Refer to => [ Safety Precautions ] Diesel Fuel Injection.
- Test drive the vehicle a minimum of 20 km/h and use full throttle at least one time. Then check the high pressure area one more time for leaks.
• If there is still air in the fuel system, the engine may switch to emergency mode during the road test. Stop the engine and erase the Diagnostic Trouble Code (DTC) memory. Refer to => [ Engine Control Module DTC Memory, Checking and Erasing ] Scan Tool Testing and Procedures. Then continue the road test.