Maintenance Manual for J2 Sedan
Electronic Control System
of Engine
166
maintain higher idling speed. Sum of all these required output torque is delivered to the torque
coordinator to carry out the calculation to get the corresponding intake density, gas mixture composition
and ignition timing.
7.
λ
Closed-loop Control
Post treatment of three-way catalyst is an effective way to decrease the concentration of hazardous
substance in the exhaust gas. The three-way catalyst can decrease the HC, CO and NO
X
by 98% or more
and transform them into H
2
O, CO
2
and N
2
. However this high efficiency can only be achieved in a very
narrow range near the excessive air factor of engine
λ
=1. The objective of the
λ
closed-loop control is to
ensure the gas mixture concentration at this range, thus, the closed-loop control system is used to get
this target.
λ
closed-loop control system functions only with oxygen sensor equipped. Oxygen sensor
can detect oxygen content of the exhaust gas at three-way catalyst side. Rarefied gas mixture (
λ
> 1)
produces a sensor voltage of about 100mV and the concentrated gas mixture (
λ
<1) produces a sensor
voltage of about 900mV. In case of
λ
=1, the sensor voltage has a jump.
λ
closed-loop control responds
to the input signal (
λ
>1= too thin mixture,
λ
<1= too thick mixture) to revise the control variable and
produce a correction factor as a multiplier to correct the fuel injection duration.
8. Evaporation Emission Control
Due to transfer of the external radiation heat and oil return heat, the fuel in tank is heated to form vapor.
According to limit of evaporative emission regulation, it is not permitted to exhaust the vapor containing
large quantity of HC composition directly into the atmosphere. The fuel vapor in the system is collected
with an active carbon canister through the conduit and flushed into the engine at appropriate time to
participate combustion. Flushing flow is controlled by the carbon canister control valve of ECM. The
control functions only when the
λ
closed-loop control system is running under the closed-loop
condition.
9. Fuel Injection Control
The fuel injection timing and impulse width is controlled to provide the best mixing of air/fuel
corresponding to the ever-changing operation condition of engine. The fuel injector is installed at the
inlet of every cylinder. The fuel is drawn from tank by fuel pump and delivered to each fuel injector.
Normally, each cylinder has one fuel injection operation with two revolutions of crankshaft. Injection
sequence of cylinders is 1-3-4-2.
10. Ignition Timing Control
The primary current to the ignition coil is controlled by connecting and disconnecting the power
transistor of primary ignition circuit to regulate the ignition timing so that the best ignition timing can be
provided according to operating conditions of engine. Ignition timing is determined by the ECM
according to the engine speed, intake quantity, coolant temperature and atmospheric pressure.
11. Self-diagnosis Function
When abnormal situation is detected by the sensor or actuator related to the exhaust control, the alarm
lamp of engine (inspection lamp of engine) lights up to inform the driver. DTCs (diagnose trouble code)
corresponding of this abnormal situation will be set in these conditions. The RAM data inside the ECM
