Combustion gases that enter the exhaust manifold are not completely burned and would continue to bum if not limited by the amount of oxygen in the exhaust system. To decrease the level of emissions emitted from the tailpipe, the Pulsed Secondary Air Injection (or Air Suction) system is used to introduce air into the exhaust flow, thereby allowing combustion to continue well into the exhaust system. This prolonged combustion (oxidation) period helps to lower the levels of HC and CO emissions that are forwarded to the catalytic converter. Additional air in the exhaust system also ensures that an adequate supply of oxygen is provided to the converter for catalyst oxidation.
Pulsed Secondary Air Injection (PAIR) systems do not use an air pump, but rely solely on the pressure differential that exists between atmospheric pressure and exhaust vacuum pulsation to draw air into the exhaust manifold.
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