Injectors — removal and installation (BMW 7 Series E32)

Faulty injectors can cause severe engine knocking and damage to its bearings. If you suspect this, let the engine idle and loosen the union nuts of the high-pressure fuel lines one by one. If the knocking disappears after loosening one of the union nuts, this indicates a faulty injector. A precise check of the injector can be performed in a workshop using special equipment.

The first signs of injector malfunctions are the following:

• Absences from work.
• Knocking in one or more cylinders.
• Engine overheating.
• Reduced engine power, high fuel consumption.
• Heavy black smoke from the exhaust pipe.

Removal

Remove the intake manifold.

Clean the high pressure fuel lines with a special cleaner.

Completely remove the high-pressure fuel lines by unscrewing the union nuts on the injectors and on the high-pressure fuel pump using a special open-end wrench with a slot (1).

Caution: Do not bend the fuel lines. Insert suitable plugs into the injectors and into the injection pump to prevent dirt from getting inside.

If the high pressure fuel line mounting brackets are removed, their installation position must be marked.





Carefully pull the fuel return lines away from the injectors.

Unscrew the injectors with a 27 mm socket. Close the injectors at the bottom with caps to prevent dirt from getting into them.

Caution: Do not drop the injectors! Install the injectors in their original positions.

Remove the heat shields (washers).

Installation

Be sure to install new heat shields between the cylinder head and the injectors. The recess should be facing up. The arrow points toward the cylinder head.

Tighten the injectors to 40 Nm.

Tighten the high pressure fuel line nuts to 20 Nm.

Install the fuel return lines.

Connect the injection timing sensor wire to the fourth cylinder injector.

If removed, install the mounting brackets in accordance with the marks made earlier.



Install the brake booster vacuum hose into the holder on the cylinder head.

Install the intake manifold. Start the engine and check the fuel system for tightness.