General System Description

These vehicles are equipped with Electronic Emission Control Units which use electronic sensors as inputs, use logic circuits to make the decisions required to lower emissions and effect smooth engine performance, and apply these decisions as outputs to various devices and solenoids to effect the changes.
The Air Injection System is designed to improve emissions performance by supplying fresh air from the air cleaner into the exhaust manifold through the air suction valve.
The Anti-Afterburn Mixture Control Valve senses intake manifold vacuum change during gear change or deceleration, and supplies fresh air into the intake manifold in order to prevent the escape of unburned fuel.
The Choke Opener System is designed to promote easy starting. When starting the engine, manifold vacuum is directed to the choke opener; thus the choke is opened a fixed amount. However, when cranking the engine, the cranking leak solenoid valve is activated and manifold vacuum to the choke opener is bled off to the air cleaner so the choke opener does not open the choke.
The Electronic Emission Control Unit makes all of the decisions to control emissions and deliver good smooth engine performance.
The Feedback Control System is designed to provide air-fuel mixture ratio feedback on this vehicle using the oxygen sensor, the EACV and the control unit. The oxygen sensor, sends the signal to the control unit in order to judge whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio. The control unit receives other signals from the speed sensor, vacuum switch, ignition coil, MAP sensor, TA sensor, TW sensor, and sends the electric current to the EACV to control the mixture.
The Idle Control System (automatic transmission only), maintains a stable idle speed under different engine load conditions. Idle control is accomplished using the A/C Idle Boost Solenoid Valve and the A/C idle boost throttle controller.