Description: First appearing on cars in 1968,
air injection systems consist of a network of hoses and tubes, a
belt-driven air pump and air-management valves. Since that time, air
injection systems have become more diverse in nature, sometimes
using the onboard computer to control system operation. Some engines
use pulse-air systems that do not inject air from an air pump.
Instead, alternating pressures in the exhaust stream are used to
pull air into the exhaust system. Once, all engines were equipped
with air injection. Today, it’s a fading technology because the
universal use of fuel injection has allowed tighter control of the
engine’s fuel delivery, significantly cleaning up the engine by
itself.
Purpose: Essentially an emissions “add-on”
installed by the automakers to help further clean up emissions, the
air injection system supplies air to the exhaust stream to promote
additional burning of exhaust gases such as hydrocarbons
(abbreviated as HC) and carbon monoxide (abbreviated as CO). Some
systems also supply air to the catalytic converter to further reduce
HC, CO and oxides of nitrogen (NOx), a major contributor to
photochemical “smog.”
Maintenance Tips/Suggestions: Air injection
systems require little maintenance, but if your car has one it
shouldn’t be completely ignored, either. Periodically, the air pump
drive belt should be checked to make sure it’s in good condition and
properly tensioned. Depending on the application, there may be a
separate drive belt, or the pump may be driven by the same belt as
other engine accessories. To determine if your car has an air
injection system, refer to the Vehicle Emission Control Information
(VECI) label underneath the hood, which will call out this emissions
subsystem if so equipped. Symptoms of problems in the air injection
system include a failed emissions test, a broken air pump belt,
backfiring through the exhaust, and an overheated/restricted
catalytic converter. You may want to consult with a professional
technician to pinpoint the exact cause.
