The air injection system (AIS) is an essential component of the automotive exhaust system. Since no internal combustion engine is 100% efficient, a certain amount of unburned fuel always remains in the exhaust gases.
Main Function of the Air Injection System
The primary mission of the AIS is to reduce polluting emissions by injecting fresh air into the exhaust flow. This air injection enables the combustion of residual unburned hydrocarbons and carbon monoxide, transforming them into less harmful carbon dioxide and water vapor.
Different Types of AIS Systems
Mechanical Air Pump System
This type uses an engine-driven pump that draws in ambient air and directs it directly into the exhaust manifold or catalytic converter.
Pulsed Air Injection System
More modern, this system uses exhaust pulsations to draw air through a check valve, without requiring a mechanical pump.
Common Failure Symptoms
Failures of the air injection system typically manifest as: abnormal noise from worn bearings, illuminated check engine light, increased pollutant emissions, or loss of engine performance.
Maintenance and Troubleshooting
Regular maintenance includes checking hoses, valves, and the pump itself. In case of failure, replacing defective components restores the efficiency of the anti-pollution system.