Operation Control Of Engine Fuel Supply System - Chery automobile Service Manual

OPERATION CONTROL OF ENGINE FUEL SUPPLY SYSTEM

1. Start engine:
In start process, ECU firstly inject to all cylinder at the same time to shorten start time. After
that, ECU will inject according to phase order.
2. Acceleration:
In acceleration process, ECU will add injection fuel by engine requirement and deal with
sensor signal below: throttle position, absolute pressure, upper dead center/ speed sensor,
multiply "basic" fuel injection time by a modification factor, which is calculated from engine
cooling temperature, throttle opening speed, and intake manifold pressure increment. When
injector is closed and if calculated injection time has a sudden change, ECU will add injection
Fuel by the modification factor mentioned above, that is to re-open injector (extra pulse) for
compensating fuel as soon as possible. In order to make vehicle more comfortable, torque
control strategy doesn't affect performance and fuel consumption in accelerating by adjusting
spark advance angle. Because exhaust regulatory become much more Stricter, a kind of much
more complicated active manage strategy is developed, which utilize some physics and
hydrokinetics phenomenon (such as fuel film mode) to gain not only a sudden change in
throttle air input but also steady air fuel ratio.
3. Deceleration:
In deceleration process, fuel engine needed is decrease to reduce pollution, ECU identifies
the phase by that throttle potentiometer signal change from high level to low level but do not
back to idle. Furthermore, it can adopt dashpot strategy to decrease output torque (reduce
engine brake), when throttle potentiometer signal shows that throttle is closed and engine is
in very high speed, ECU considers it's satisfied condition that ECU will minish by-pass air
input by controlling step motor step by step.
4. Cut off:
ECU will adopt cut off strategy when ECU identifies that throttle is in idle position (throttle
potentiometer signal) and hot engine speed exceeds 1500r/m. The warm up strategy is
determined by the speed when engine coolant temperature increase strategy is running. Fuel
will be supplied again to system if throttle is not closed and hot engine speed is lower than
1400r/m. In high speed, ECU will adopt cut off strategy (part cut off) if throttle is not closed
completely but manifolds pressure is very low.
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