Delphi Multec 3.5, Руководство по применению

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Multec 3.5 Fuel Injector Application Manual Fundamentals
Delphi Energy and Chassis Systems Revision: 11/05-1 2-19
operation can cause EGR system problems. Consult the Delphi EGR
applications manual for advice on how to avoid problems when disabling
the EGR system.
2.2.7.5 Cold Temperature/Low Battery Voltage Startability
Refer to Section 5
The combination of cold temperature and low system voltage places an
added burden on the fuel system. Combustion at cold temperature
requires additional fuel due to effects mentioned in the previous sections.
Low system voltage not only affects the output of the fuel pump, but can
also affect the ability of the injector to open (a minimum operating voltage
(MOV) is specified for each Multec 3.5 injector model). Customer
startability requirements under these conditions must be fully understood
prior to the correct selection of the fuel rail assembly and fuel pump.
Typically, customers require the fuel injectors to open at the low voltage
limit for engine controller and ignition system operation. They also
require the fuel pump and pressure regulator to provide adequate flow and
pressure control for reliable starting. Engine controller software and
calibration for fuel control is critical at these low voltage and temperature
conditions. Delphi recommends the use of voltage offset compensation in
the engine calibration to allow for precise metering of fuel even at low
system voltage.
2.2.7.6 Altitude Effects on Combustion
See Section 5
The density of air is lower at higher altitudes, reducing the amount of fuel
required to obtain complete combustion. On speed density systems, the
engine controller compensates for this by using feedback from various
sensors on the engine to reduce the commanded opening times for the
injector. On mass airflow systems, the engine controller relies on
feedback from the intake air flow meter to reduce the commanded opening
times for the injector.
Lower atmospheric pressure also reduces fuel rail and injector absolute
operating pressure, increasing the chance for vapor to form upstream of
the injector outlet. The combination of lower atmospheric pressure and
higher operating temperature can cause vapor handling problems. These
problems must be addressed during system design.
2.2.8 Maximum Power Fueling Requirements
Under certain conditions, such as under hard acceleration (high throttle
angle) or wide-open throttle (WOT) conditions, the air/fuel ratio is
enriched to provide for maximum engine power. This condition is usually
referred to as power enrichment (PE), and is typically scheduled at an A/F
of 12.5:1 (although lower PE A/F is possible).