BMW S58, Руководство пользователя

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S58�Engine
10.�Fuel�Preparation
79
The�S58�engine�has�two�high-pressure�pumps�connected�in�parallel.�The�two�high-pressure�pumps
are�operated�in�alternation�every�30�seconds.�That�ensures�that�both�high-pressure�pumps�are�evenly
loaded�when�the�vehicle�is�being�driven�moderately.�When�the�vehicle�is�being�driven�harder�or�at
full�power,�both�high-pressure�pumps�are�operated�simultaneously.�This�was�necessary�in�order�to
satisfy�the�higher�throughput�volume�of�fuel�at�high�engine�speeds.�Control�is�effected�by�means�of�the
volume�control�valve�of�the�high-pressure�pumps�using�a�PWM�signal.
The�piston�and�tappet�of�the�high-pressure�pump�have�been�modified�and�materials�adapted�but�its
general�design�is�familiar�from�the�previous�3,�4,�6�and�8-cylinder�engines.�The�triple�cams�on�the�high-
pressure�pump�drive�mechanisms�for�each�pump�have�an�interval�of�120°�in�each�case.�The�two�drive
cam�pairs,�which�drive�the�two�high-pressure�pumps,�are�arranged�so�that�there�is�a�delivery�every�60°.
Work�on�the�fuel�system�is�only�permitted�after�the�engine�has�cooled�down.�The�coolant�temperature
must�not�exceed�40�°C.�This�stipulation�must�be�observed�without�fail,�as�otherwise�there�is�a�risk�of
fuel�being�sprayed�back�on�account�of�the�residual�pressure�in�the�high-pressure�fuel�system.
When�working�on�the�high-pressure�fuel�system,�it�is�essential�to�adhere�to�conditions�of�absolute
cleanliness�and�to�observe�the�work�sequences�described�in�the�repair�instructions.�Even�the�slightest
contamination�and�damage�to�the�screwed�fittings�of�the�high-pressure�lines�can�cause�leaks.
When�working�on�the�fuel�system�of�the�S58�engine,�it�is�important�to�ensure�that�the�ignition�coils�are
not�fouled�with�fuel.�The�resistance�of�the�silicone�material�is�greatly�reduced�by�sustained�contact
with�fuel.�This�may�result�in�flashovers�on�the�spark�plug�head�and�thus�in�misfires.
• Before�making�any�modifications�to�the�fuel�system,�without�fail�remove�the�ignition�coils�and
protect�the�spark�plug�shaft�against�ingress�of�fuel�by�covering�with�a�cloth.
• Prior�to�a�new�installation�of�the�solenoid�valve�injectors,�the�ignition�coils�must�be
disassembled�and�the�highest�possible�level�of�hygiene�ensured.
• Ignition�coils�heavily�fouled�by�fuel�must�be�replaced.
• The�CVO�function�comprises�the�"injector"�and�"digital�engine�electronics"�(DME)�system
components.�These�components�therefore�have�to�be�identified�with�the�vehicle�identification
number�in�the�EPC�in�the�event�of�a�replacement.
• Where�injectors�and�DME�support�the�CVO�function,�the�injection�quantity�compensation
during�the�replacement�of�one�of�the�components�is�omitted.
• An�excessive�rotational�angle�at�the�injector�shank,�and�excessive�tensile�and�compressive
forces�during�removal�and�installation�can�lead�to�damage�and�therefore�leaks�in�the�fuel
system.
• For�any�service�work�required,�the�current�information�and�specifications�in�the�documents�in
the�Integrated�Service�Technical�Application�(ISTA)�must�be�observed�in�each�case.