Direct Injection
The fuel injectors are a high pressure multi-hole type with solenoid opening. The function of the fuel injector is to attain an optimized mixture of fuel and air in the combustion chamber. Since the engine only runs in homogeneous operation, fuel is injected early during the inlet stroke (piston on its way down) which means that the spray has time to homogenize/mix with the air before ignition takes place.
| 1. Retaining clip | 6. Connector. |
| 2. Support ring | 7. Tolerance ring |
| 3. O-ring | 8. C-ring (snap-ring) |
| 4. Stop washer | 9. Seal, Teflon |
| 5. Sealing area against fuel pipe | 10. Sealing area against combustion chamber |
The engine control module (ECM) controls the fuel injectors regarding injection timing and injection length. The fuel injectors have six holes. The capacity of the fuel injectors differs between "high performance engines" B4204T9/T10- and "intermediate performance engines" B4204T11/T12/T15. The maximum flow (static flow rate) differs between the injectors. The value for B4204T9/T10 is approx. 20 cm3/s whilst for B4204T11/T12/T15 it is approx. 17.5 cm3/s. The values apply at a fuel pressure of 10 MPa (100 bar).
The fuel quantity and thus the injection time at idle varies depending on alternator and AC load, but is within the range 0.9-1.5ms and with a fuel pressure of between 5-15MPa (50-150 bar). At maximum power output the injection time is 6-7ms and the fuel pressure 20MPa.
After the fuel injector has been removed, the following components must be replaced with new ones before reinstallation: retaining clip (1) support ring (2), O-ring (3), stop washer (4), seal, Teflon (9).
During replacement, ensure to follow the instructions in Volvo's VIDA. An incorrectly installed fuel injector can result in increased fuel consumption with increased CO2 emissions as a result, an interrupted combustion process that can cause engine damage, etc.