CARBURETED
Ignition control system is designed to reduce emissions throughout all engine operating ranges by controlling ignition timing. System consists of a vacuum advance control unit on distributor.
A dual-diaphragm (main and auxiliary) type vacuum controller is used on Justy models. A single diaphragm type vacuum controller is used on all others.
FUEL INJECTED
The ignition system on fuel injection systems, is composed of battery, ignition coil, distributor, spark plugs, fuel injection control unit and wires. The crank angle sensor, built into distributor, detects reference crank angle and positioned crank angle.
Electronic signal of both angles is transmitted to control unit which is used in common with fuel injection systems. The control unit calculates spark advance angle and determines spark timing.
The electronic signal of spark timing determined by the control unit is transmitted to power transistor. It makes a primary circuit to the ignition coil and high voltage current is generated in secondary circuit.
High voltage of secondary circuit is distributed to spark plug of each cylinder and discharged there. Spark advance angle is calculated from following 3 factors: engine speed compensation, advance when starting engine, and advance in all driving conditions except engine starting. (Scheme 20)
The Justy distributor is equipped with both vacuum and electrical advance. Electrical advance is constantly operative, and is controlled by Ignition Timing Unit (ITU). On all other models, distributors are equipped with vacuum advance only. Vacuum advance on both systems is controlled by engine vacuum. The Justy system is equipped with a dual-diaphragm advance unit. Intake manifold vacuum is applied to auxiliary side of distributor vacuum control unit during idle, low-load operation and deceleration in order to provide an advance angle.
Vacuum produced in advance port is applied to main diaphragm side in relation to opening angle of throttle valve. This main advance provides additional advance angle. (Scheme 16)
Scheme 16
Scheme 17
Anti-Afterburning System (Except Justy)
The anti-afterburning system prevents the temporary heavy concentration of the air/fuel mixture during rapid deceleration by introducing air into the intake manifold. This prevents afterburning in the exhaust system.
During constant speed running, the valve is closed because pressure in chambers "A" and "B" are equal. During deceleration, with throttle closed, vacuum in the intake manifold increases and the pressure in chamber "B" decreases. The diaphragm is forced down to open the valve. This permits fresh air to be drawn into the intake manifold through the filter.
After deceleration, pressure in chamber "A" gradually becomes equal to pressure in chamber "B" as air flows through the orifice. The diaphragm is then pushed up by a spring, which closes valve. (Scheme 18)
Scheme 18
On fuel injected models, distributor advance is controlled strictly by electrical signals from ECM.
Up-Shift Control System
Shift-up control system is provided on auto. trans. equipped vehicles only and is used to reduce CO emissions by providing rapid engine warm-up. If engine is started while coolant temperature is in the preset temperature range, ECM holds transmission in a kickdown state for a certain duration of time. (Scheme 19)
Scheme 19
Fuel Injected (Turbo Vehicles)
Ensure there is air flow from air intake side to EGR vacuum valve side. Ensure there is no air flowing from thermo vacuum valve side to air intake boot side.
HIGH ALTITUDE KIT
When principally operating vehicle at altitudes above 4000 feet (1200 m), emission control system requires minor modification to meet emission control standards at high altitude.
Note. When installing a high altitude kit, refer to manufacturer's instructions supplied with the kit.
When a vehicle modified to high altitude specifications is principally used at altitudes below 4000 feet (1200 m), the emission control system must be remodified to the original specifications.
Scheme 20
Air Passage Hose
Check hose and its connection for leakage and looseness. If leakage is found, replace it with a new one.
Vacuum Line
Check vacuum line for leakage and looseness. To do so, disconnect vacuum hose from Anti-Afterburning Valve (AAV), then run the engine. Ensure that air is sucked into vacuum hose. If not, vacuum line is defective.
Anti-Afterburning Valve (AAV)
Hold a piece of paper under the AAV, run engine to 3000 RPM and close the throttle quickly. If paper is sucked to the AAV at this moment, the AAV is operating normally. If not, the AAV is defective. Replacement is necessary.