DESCRIPTION
The air injection system adds a controlled amount of fresh air to the exhaust gases at the exhaust manifold, or downstream to the catalyst to aid in oxidation of the exhaust gases. This results in reduced levels of carbon monoxide (CO) and hydrocarbon (HC) emissions.
The 2.2L and 2.5L TBI system uses an Air Aspirator System (AAS). This system uses an aspirator valve, hoses and tubing.
2.2L & 2.5L TBI Models
The air aspirator valve is a reed-type, one-way check valve. This valve is connected to a tube from the exhaust catalyst. A fresh air hose is connected to the valve and to the TBI air filter assembly. When exhaust negative pressure pulses are strong enough to create a vacuum pulse, the reed valve in the aspirator valve is drawn open, allowing fresh air to enter the catalyst.
Positive pulses (pressure) in the exhaust cause the reed valve to remain closed, protecting the connecting hose, resonator and air filter assembly from exhaust gases. The resonator is installed between the aspirator valve and air filter housing to minimize exhaust noise under hood. (Scheme 15)
Scheme 15
SERVICE PROCEDURES
Complete system should be checked at regular intervals. Belts must be in good condition and set to proper tension.
Remove air supply hose from aspirator valve inlet. With engine at idle in neutral, the negative exhaust pulses (vacuum) can be felt at the inlet. If hot exhaust gases are felt escaping from the valve, the valve must be replaced.