Air￿Mass￿Determination - BMW S58 Owner's Handbook Manual

S58￿Engine
8.￿Intake￿Air￿and￿Exhaust￿System
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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.
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Explanation
Exhaust￿turbocharger,￿cylinders￿1-3
Intake￿silencer￿cover
Intake￿plenum
Indirect￿charge￿air￿cooler
Intake￿air￿temperature￿sensor
Charging￿pressure￿sensor￿before￿throttle￿valve
Unfiltered￿air￿pipe,￿left
Intake￿snorkel,￿left