What is the purpose of a secondary air pump?
3 Answers
The secondary air pump functions to inject air into the exhaust manifold after a cold engine start. Its purpose is to enable the incomplete combustion of the air-fuel mixture to undergo a second combustion process within the exhaust pipe, thereby reducing emissions and meeting current stringent environmental requirements. The working principle of the secondary air pump involves driving the air pump via the crankshaft belt when the engine is running, pumping a large volume of low-pressure air through a hose into the diverter valve. The secondary air system is one of the external purification devices designed to reduce exhaust emissions. By introducing additional air into the exhaust gases, it increases the oxygen content, allowing unburned harmful substances such as carbon monoxide and hydrocarbons to undergo further combustion under high-temperature conditions.
The secondary air injection pump plays a crucial role in vehicles. I often notice many car owners don't understand the function of this small device, which is actually designed to meet environmental emission requirements. During cold engine starts, low temperatures lead to incomplete combustion, resulting in unburned hydrocarbons in the exhaust. That's when the secondary air injection pump kicks in, injecting fresh air into the front end of the catalytic converter. With this additional oxygen supply, it helps re-burn residual fuel, significantly reducing harmful emissions. Simultaneously, it assists the catalytic converter in reaching optimal operating temperature faster, improving conversion efficiency. This pump typically operates for just 1-2 minutes during cold starts and automatically shuts off once the engine warms up. If it malfunctions, the vehicle will definitely fail emission tests, and the check engine light may illuminate. During repairs, I've encountered many cases where clogged pumps caused abnormal fuel consumption increases.
Speaking of the secondary air injection pump, its main function is to give the exhaust system a boost during cold starts. Having worked with exhaust systems across different vehicle models, I've found it to be a crucial assistant for environmental protection and emission reduction. When the engine first starts and hasn't reached optimal temperature, a significant amount of unburned fuel mixture gets expelled. That's when the secondary air injection pump kicks in immediately, injecting fresh air into the front section of the exhaust pipe. It's like adding a blower to a furnace, providing sufficient oxygen for residual fuel to burn completely. This not only reduces harmful substances in the exhaust but also helps the catalytic converter quickly reach its optimal operating temperature of 500 degrees. Although the entire process lasts only a few minutes, it makes a remarkable difference in emission data. If you see blue smoke from the exhaust pipe during cold starts in winter, it's likely due to a stuck solenoid valve in this pump. With China's stringent China VI emission standards, this small component must remain fully operational.
