The AI control system/AS control system is a system that feeds air into the exhaust manifold to recombust the uncombusted gas in the exhaust to lower HC and CO emissions. The difference between these two systems is that the AI control system uses a pump to force feed the air while the AS control system uses the vacuum created in the exhaust manifold to draw in air. The AI control system will be explained here. This system is operated by the engine ECU when HC and CO exhaust emissions increase when the engine is cold and the vehicle is decelerating. This system is not used under any other conditions. When all of the operation conditions exist, the engine ECU operates the electric air pump while the VSV operates at the same time to feed the intake manifold vacuum to the air injection valve. This opens the passage to feed the compressed air to the exhaust manifold. The engine ECU estimates the total volume of gas flowing in the TWC based on the signal from the air flow meter.
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Past AI control systems kept the air pump operating at all times. Therefore, an ASV (Air Switching Valve) was used instead of an air injection valve to expel the compressed air when the system was not in operation.