CS35 2013.04
3.1.13-5 3.1.13-5Electronic Control System - ME7
testing the engine and the operating condi-
tions.
4. Fuel cut - off
The injection stops (by stopping injector)
while slowing down (for example, when throt-
tle is placed on idling position and engine is
running with high speed). It ensures that
unburned gas will not be discharged and be
started again in above different conditions.
Air - fuel Ratio Feedback Compensation
(Closed - loop System)
The air - fuel mixture must be close to stoi-
chiometric air - fuel ratio (14.7) to ensure that
the three way catalyst conversion process is
fully carried out and reach high purification
rate of CO, HC and NOx in exhausting.
λ closed loop control system can work only
with oxygen sensor equipped. Oxygen sensor
monitors the oxygen content in the exhaust-
ing in the side location of three way catalytic
converter, lean mixture (λ > 1) generate about
100mV sensor voltage, rich mixture (λ < 1)
produces about 800 mV sensor voltage.
When λ = 1, the sensor voltage has a jump. λ
closed - loop control responds to the input
signal (λ is greater than or equal to 1 lean
mixture, λ is less than or equal to 1 rich mix-
ture) modify the control variables, resulting in
correction factor as a multiplier to correct the
fuel injection duration. When any one of the
following conditions is met, ECM exits the
closed - loop control.
• When the engine starts to operate and
the injection quantity is increased after
the engine starts.
• When the engine coolant temperature is
too low.
• When the load is high and fuel injection
capacity is increasing.
• When the fuel is cut off.
• When the oxygen sensor is cooled.
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