Air Injection System: Description

NOTE: No information for 1.6L models is available.

The purpose of the air injection system is to reduce exhaust emissions by oxidizing hydrocarbons (HC) and carbon monoxide (CO) during cold engine operation.

The system is composed of air suction valve(s), thermosensor (used on all Calif. models and Federal FWD models), solenoid valve, check valve, thermostatic air cleaner (TAC), silencer(s), various hoses and tubing and the electronic control module (ECM). Depending on model and application, secondary (fresh) air is supplied to exhaust ports on either one (Calif.) or both (Federal) cylinder banks.

There are 2 types of air suction valves used with the air injection system. On all California models and Federal 2WD models, air suction valve(s) include a cut-off valve. Federal 4WD models use air suction valves without cut-off valve. See Fig 1 and Fig 2

Fig 1: Sectional and Exploded View of Nippondenso and NOK AIR Suction Valves Used on Federal 2WD and all California models.

Fig 2: Sectional and Exploded View of NOK Air Suction Valves Used on Federal models only.