Maintenance Manual for J2 Sedan
Electronic Control System
of Engine
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cancelled. In starting work conditions, spark advance are also adjusted and vary with the engine
temperatures, intake air temperatures and engine speeds.
4. Warming-up and Heating Control of Three-way Catalyst
With engine started at low ambient temperature, intake quantity of cylinder, fuel injection and electronic
ignition are all adjusted to compensate the higher requirement of the engine torque; this process
continues until the temperature is proper. During this stage of running, the most important factor is the
quick heating of the three-way catalyst, for fast transition to the three-way catalyst functioning can
markedly reduce the emission. Under this operation condition, the “heating three-way catalyst” may be
performed by postpone the ignition advance angle properly to take advantage of the exhaust gas.
5. Acceleration/Deceleration and Back-tow Fuel Cut Control
Part of the fuel injected to the intake manifold will not reach the cylinder in time to participate
follow-up combustion stroke. Instead, it forms a film on intake manifold wall. With increasing of load
and injection duration extension, fuel stored in the film will build up dramatically. When the throttle
opening increases, part injected fuel will be absorbed by the film. Therefore, corresponding amount of
fuel must be added for compensation and to prevent the mixture from thinning during acceleration.
Once load factor is reduced, the additional fuel contained in the fuel film on intake manifold wall will be
re-released, and then it is necessary to reduce the injection duration accordingly during acceleration
course. Back-tow and towing operation condition refers to conditions that the power supplied by the
engine at the fly wheel is negative value. In this case, the engine friction and pumping gas loss can be
used to make vehicles slow down. In back-tow or towing operation condition, fuel injection is cut off in
order to reduce the fuel consumption and the emission, more importantly, the three-way catalyst can be
protected correspondingly. Once engine speed decreases to the specific fuel supply recovery speed
above idling, the fuel injection system will re-supply. In fact, ECM program has a rotation speed
recovery range which depends on the changes of such parameters as engine temperature, dynamic
change of engine speed, which can also prevent the engine speed from dropping to the specified
minimum through calculation. Once the fuel injection system re-supplies fuel, the supplemental fuel
will be supplied by using the initial injection pulse and the fuel film on the intake manifold wall will be
formed. After resumption of fuel injection, torque-based control system makes the increase of engine
torque slow and steady (smooth transition).
6. Idle Control
At idle speed, the engine does not provide torque to the fly wheel. To ensure the engine running stably at
the lowest possible idle speed, the closed-loop idle speed control system should keep the balance
between the generated torque and the "power consumption" of engine. The necessary power should be
generated with idling speed to meet the load requirements of all aspects, including those come from
internal friction from the engine crankshaft and valve mechanism, as well as the auxiliary components,
such as coolant pump. The system is based on the torque-based control strategy, which determines
required output torque of engine to maintain the required idle rotation speed under any operating
conditions with a closed-loop idle speed control strategy. The output torque increases with decreasing of
engine speed and decreases with rising of engine speed. The system request greater torque to response to
the new "disturbance factors", such as the switch of the air-conditioning compressor. With low engine
temperature, it is necessary to increase the torque to compensate the greater internal friction loss and/or
