Anti-AFTERBURN Valve

During sudden deceleration, a rich air/fuel mixture is immediately introduced into combustion chambers and some of it passes unburned into the exhaust manifold. Air supplied by the air pump leans this mixture. This could cause abnormal combustion, or afterburning, in the exhaust system. To prevent this, the anti-afterburn valve will only allow air from the air pump into intake manifold according to changes in engine load. This keeps air intake at proper levels so air/fuel mixture is properly burned in cylinder. This valve is controlled by intake manifold vacuum.