BMW S58, Руководство пользователя

Страница: 70 / 102

S58�Engine
8.�Intake�Air�and�Exhaust�System
64
Index Explanation
7 Exhaust�turbocharger,�cylinders�1-3
8 Intake�silencer�cover
9 Intake�plenum
10 Indirect�charge�air�cooler
11 Intake�air�temperature�sensor
12 Charging�pressure�sensor�before�throttle�valve
13 Unfiltered�air�pipe,�left
14 Intake�snorkel,�left
8.1.2.�Air�mass�determination
On�the�US�and�Europe�versions,�the�intake�air�mass�flow�is�not�measured�by�a�hot-film�air�mass�meter
but�calculated�by�the�DME.�For�this�calculation,�an�experience-based�filling�calculation�(filling�model)�is
programmed�in�the�DME.�The�following�signals�are�applied�to�this�calculation.
Signals:
• VANOS�setting�(load�sensing)
• Throttle�valve�position�(throttling)
• Intake�air�temperature�(air�density�correction)
• Engine�temperature�(air�density�correction)
• Engine�speed�(cylinder�charging)
• Intake�manifold�differential�pressure�(throttling�correction)
• Ambient�pressure�(air�density�based�on�altitude�correction).
The�air�mass�calculated�in�this�way�is�adjusted�and�corrected�if�necessary�in�line�with�the�oxygen
sensor�signals�(air/fuel�ratio)�and�the�injection�period�(fuel�quantity).�Should�the�oxygen�sensors�fail,�a
fault�memory�entry�is�made�in�the�DME�(air�mass�plausibility).�Adjustment�to�the�calculated�air�mass
does�not�apply�in�this�case.
The�monitoring�of�the�tank�ventilation�system�for�leaks�that�is�legally�required�on�the�US�is�performed
by�the�venturi�nozzle�pressure�sensor�on�the�S58�engine.�Therefore,�it�has�been�possible�to�dispense
with�the�hot�film�air�mass�meter.
8.1.3.�Tank�ventilation�system
In�a�carbon�canister�the�fuel�vapors�are�stored�temporarily�and�fed�for�combustion�via�the�tank�vent
valve.�With�turbocharging�it�is�necessary�to�also�adapt�this�system�to�the�specifications.