Fuel Injector: Service and Repair
Fuel (Piezo) 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)
• Socket (T40055)
• Tool Insert AF 19 (V.A.G 1331/5)
Removing
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 correction value for the new injector must be programmed into the Engine Control Module (ECM). Refer to => [ Injector Correction Values, Check and Adjust ] Testing and Inspection.
• The illustration shows the removal and installation of injectors for cylinder bank 2. The procedure for the cylinder bank 1 injectors is almost identical, except for a few steps that are omitted.
- Remove the engine cover. Refer to => [ Engine Cover ] Engine Cover.
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 plug.
• 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 ] Service and Repair.
- Pull the center piece upward - arrow - and remove the return line connections from the injectors.
- Disconnect the connector from the injector to be removed.
- Loosen the injector line union nuts - 1, 6 and 7 - at the injectors using the socket (T40055).
- Loosen the injector line union nuts - 1, 6 and 7 - at the fuel rail using the socket 14 mm (3150) or the tool insert AF 19 (V.A.G 1331/5).
- Remove the sealing cap bolts - arrows -.
- Pull the caps upward and rotate them 90° (1/4) turn.
- Remove the injector tensioning plate nuts - arrows -.
- Remove the injectors using the puller (T10055) and the adapter (T10055/1).
- Place the injectors on a clean cloth.
Installing
Important information when installing the fuel injectors:
• Replace the following components, seals or O-rings with each removal and installation: "Copper washer", "injector shaft O-ring" and "injector return O-ring"
• The following components, seals and/or O-rings must be replaced whenever a fuel injector is replaced: "Tensioning plate", "fuel injection line", "copper washer", "fuel injection shaft O-ring" and "injector return O-ring"
• When installing, the fuel injectors and injection lines may only be installed to the same cylinder as before.
• Check the fuel injectors and installed locations of 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 being reinstalled:
- Spray the tip of the fuel injector with a rust removing spray. Remove the rust or oil particles with a cloth after approximately 5 minutes.
- If an injector is very dirty, clean the tip around the copper washer with a soft brush. Do not let the brush come in contact with the holes for the jets.
- To remove the used copper washer from the fuel injector, clamp the washer carefully in a vise until the vice jaws prevent the washer from turning. Pull the fuel injector out of the copper washer by hand with a slight twisting and pulling motion.
- Use a scraper to remove any deposits under the copper washer.
- Use a plastic socket to install the copper washer.
- Check the O-ring for the fuel return line connection at the injector for damage and deformation.
Is there identifiable O-ring damage or deformation:
- Replace the O-ring for the fuel return line connection. O-rings must be lubricated when installed.
- Coat 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.
Continuation
- To remove rust particles on the fuel injector sealing surface, clean the fuel injector port 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 nuts on the high pressure or injection lines hand tight.
- Make sure the lines are seated correctly without tension.
- Tighten the high pressure lines:
=> [ Tightening the High Pressure Line to the Fuel Rail using a 14 mm Wrench ] Cylinder Head Cover Overview.
=> [ Tightening the High Pressure Line to the Fuel Injector using a 17 mm Wrench ] Cylinder Head Cover Overview.
=> [ Tightening the High Pressure Line to the Fuel Rail using a 19 mm Wrench ] Cylinder Head Cover Overview.
- Press the return line connections carefully over the sealing ring onto the injector (check the sealing ring first for damage). The connection must engage audibly. Then press the center piece down carefully.
- Check and adjusts the injector correction values. Refer to => [ Injector Correction Values, Check and Adjust ] Testing and Inspection.
- Bleed the fuel system and then check for leaks. Refer to => [ Fuel System, Bleeding and First Time Filling ] Fuel System, Bleeding and First Time Filling.
If there are leaks even though the correct tightening specification was used, 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 (12.5 mph) and using 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. Turn off the engine and erase the Diagnostic Trouble Code (DTC) memory. Refer to the vehicle diagnostic tester. Then continue the road test.