In 1966, a motor vehicle emissions control strategy was introduced and named secondary air injection. It is simply referred to as air injection. It is a system in which fresh air is injected into the exhaust stream to make it possible for fuller secondary combustion of the exhaust gases.
There are different methods of injection and they usually determine the mode of control of the exhaust emissions. Also, the point which acts as the entrance for the air to the exhaust system is also a determinant. This is one of the things that has changed over the course of the improvement of this technology. In the beginning, the system used to inject the air at a close distance to the engine and was mainly in the exhaust manifold or the cylinder head`s exhaust ports. It is them that offered the oxygen that was required for the oxidation of the partially burned or the unburned fuel that was contained in the exhaust prior to its ejection from the tailpipe. Back in the 60s and the 70s, there was plenty of unburned and partially burned fuel. For that reason, the invention of the secondary air injection was something that tremendously lowered the emissions in the tailpipe. Nevertheless, the additional re-combustion heat which was a result of a maladjusted carburetor or misfiring was a great worry for the damage of the exhaust valves. With the P2442 emission control strategies becoming more effective and sophisticated there was shrinking in the amount of partially burned and unburned fuel in the stream of exhaust. This toyota tundra secondary air injection system was put as a way of supporting the catalytic converter to ensure that it functions efficiently. This system was implemented in the following ways. Pumped air injection These are systems that utilize vane pumps that are known as an air pump. The air intake of the pump, through the use of a rotating screen, is filtered for the exclusion of the dirt particles which could have a big size capable of damaging the system. The delivery of the air is done under very light pressure on the points of injection. Aspirated air injection It is also possible to achieve air injection by exploiting the negative pressure pulses that are found in the exhaust system. An aspirator valve is put in the air injection pumping and this works by directly drawing the air from the side of the filter that is clean. It is important to note that the functionality of the aspirator is at engine idle. If you want to get more enlightened on this topic, then click on this related page: https://en.wikipedia.org/wiki/Air_pump.
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