Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel injection system
For the engine S63 TOP, the high-pressure injection is used as is already known from engine N55. It is different from the high precision injection through the use of injectors with multi-hole nozzles. The Bosch HDEV 5.2 injector is a multi-hole valve that opens to the inside as opposed to the Piezo injector, which opens to the outside. The HDEV 5.2 injector is marked by high variability with regard to jet angle and jet shape and has been designed for a system pressure of up to 200 bar.
Another difference is the welded rail. The individual fuel injection lines are no longer screwed together with the rail but welded. With the engine S63 TOP, the fuel low-pressure sensor was omitted. The known fuel quantity control using the recorded engine speed and load is used.
The high pressure pump is already known from the 4, 8 and 12 cylinder engines. In order to ensure sufficient fuel pressure at any load condition of the engine, one high pressure pump each is used for each cylinder bank for the engine S63. The high pressure pump is screwed onto the cylinder head and is driven by the exhaust camshaft.
The following illustration shows the arrangement of the components that are involved in the fuel injection system.
| Index | Explanation |
|---|---|
| 1 | Fuel line |
| 2 | Fuel quantity control valve |
| 3 | HDEV 5.2 solenoid-controlled injector |
| 4 | High pressure line from rail to injector |
| 5 | Rail |
| 6 | High pressure line from high pressure pump to the rail |
| 7 | Fuel line from the fuel tank |
| 8 | High pressure pump (Bosch 5th generation) |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.