Software Multec 3.5 Fuel Injector Application Manual
5-12
Delphi Energy and Chassis Systems
Revision: 11/05-1
5.2.3.9 Catalytic Converter Protection Mode
Under certain conditions, catalytic converter temperatures can exceed
manufacturer recommendations. An option to reduce temperature in the
converter is to add additional fuel (catalytic converter protection mode).
Resulting A/F ratios may be richer than power enrichment A/F ratios.
Injector flow rates must be sized to include this factor.
5.2.3.10 Individual Cylinder Fuel Trim vs. Adaptive Multipliers
Often times there are cylinder-to-cylinder A/F imbalances. These
imbalances can be compensated for through development work and
incorporation into the software of individual cylinder fuel trim constants.
5.2.3.11 Steady State Conditions
Steady state conditions are engine changes that occur slowly, (i.e.,
stabilized operation with no or extremely slow changes in speed, load,
temperature, etc.). Steady state conditions are easiest to predict.
5.2.3.12 Transient Conditions
Transient conditions are those conditions that require an adjustment of
fueling based on larger or more rapid changes in throttle position or
engine RPM than can be accommodated through the normal closed-loop
control.
Acceleration Enrichment (AE)
During acceleration, the change in airflow rate to the cylinder is faster
than the control system’s corresponding adjustment to the fuel flow rate.
In addition, the decrease in manifold vacuum (increase in MAP) causes
fuel to be deposited on the manifold walls. Extra fuel is added during
acceleration to compensate for and maintain the proper A/F ratio in the
cylinder
Deceleration Fuel Enleanment (DE)
During deceleration, the fuel on the intake manifold walls is evaporated
due to the reduction of pressure (decrease in MAP), resulting in more fuel
to the cylinder. To compensate, a correction factor causes less fuel to be
pulsed from the injectors to maintain the proper A/F ratio.
Deceleration Fuel Cut Off (DFCO)
During more extended overrun (low MAP) conditions, such as going
down a long hill, it is desirable to completely turn off the injectors. This
is necessary, as combustion at extremely low MAP’s is unstable, which
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