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.
Air supply (Ver. 1): Notes
The N55 is a BMW TwinPower Turbo engine featuring dual forced induction. Engine N55 features 1 twin-scroll exhaust turbocharger which is driven by 2 exhaust ports (dual turbocharging).
| Item | Explanation |
|---|---|
| A | Unfiltered air |
| B | Clean air |
| C | Heated charge air |
| D | Cooled charge air |
| 1 | Unfiltered air line |
| 2 | Intake silencer with intake filter |
| 3 | Hot-film air mass meter |
| 4 | Crankcase ventilation |
| 5 | Twin-scroll turbocharger |
| 6 | Charge air cooler |
| 7 | Intake air temperature pressure sensor |
| 8 | Fuel tank ventilation shutoff valve (to 03/2012) |
Heavy vehicles with automatic transmissions or all-wheel drive vehicles have a second supply point (= second purge air line) from the tank vent valve via the suction jet pump (= Venturi nozzle) in front of the compressor.
Until 03/2012, a shutoff valve is installed for the diagnosis (= Continental high pressure pump)
From 03/2012, a pressure sensor is installed for the suction jet pump for the diagnosis (= Bosch high pressure pump)
European version:
These vehicles also have the 2nd purge air line. However, it will not be diagnosed. Neither a shutoff valve nor a pressure sensor is installed for the Venturi nozzle.
NO RELATED
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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.