The AIR management system, is used to provide additional oxygen to continue the combustion process after the exhaust gases leave the combustion chamber. Air is injected into either the exhaust port(s), the exhaust manifold(s) or the catalytic converter by an engine driven air pump. The system is in operation at all times and will bypass air only momentarily during deceleration and at high speeds. The bypass function is performed by the Air Control Valve, while the check valve protects the air pump by preventing any backflow of exhaust gases.
The AIR system helps reduce HC and CO content in the exhaust gases by injecting air into the exhaust ports during cold engine operation. This air injection also helps the catalytic converter to reach the proper temperature quicker during warmup.
The AIR system utilizes the following components:
- An engine driven AIR pump.
- AIR Control valves (Air Control, Air Switching).
- Air flow and control hoses.
- Check valves.
- A dual-bed, three-way catalytic converter.
The belt driven, vane-type air pump is located at the front of the engine and supplies clean air to the AIR system for purposes already stated. When the engine is cold, the ECM energizes an AIR control solenoid. This allows air to flow to the AIR switching valve. The AIR switching valve is then energized to direct air to the exhaust ports.
If the AIR control valve detects a rapid increase in manifold vacuum (deceleration), certain operating modes (wide open throttle, etc.) or if the ECM self-diagnostic system detects any problem in the system, air is diverted to the air cleaner or directly into the atmosphere.
The primary purpose of the ECM's divert mode is to prevent backfiring. Throttle closure at the beginning of deceleration will temporarily create air/fuel mixtures which are too rich to burn completely. These mixtures become burnable when they reach the exhaust if combined with the injection air. The next firing of the engine will ignite this mixture causing an exhaust backfire. Momentary diverting of the injection air from the exhaust prevents this.
The AIR system check valves and hoses should be checked periodically for any leaks, cracks or deterioration.Removal & Installation
Before servicing the vehicle, refer to the Precautions Section.
NOTEDisconnecting the negative battery cable on some vehicles may interfere with the functions of the on-board computer systems and may require the computer to undergo a relearning process, once the negative battery cable is reconnected.
NOTEIf working near and/or around the SRS system and components, be sure to properly disable the SRS system. See disarming/arming the SRS system.
- Disconnect the negative battery cable.
- Remove the AIR control valves and/or adapter at the pump.
- Hold the pump pulley from turning and loosen the pulley bolts. Lift the belt drive tensioner to the raised position remove the pump and pulley assembly.
- Unscrew the pump mounting bolts and then remove the pump pulley.
Unscrew the pump mounting bolts and then remove the pump.
- Position the pump into place and secure it with the mounting bolts.
- Install the pump pulley.
- Install the air pump drive belt and adjust pump belt with the pump adjustment bolt, as required.
- Install the AIR control valves and/or adapter.
- Using the GM diagnostic scan tool or aftermarket equivalent reprogram the necessary systems and components. Be sure to follow the scan tool manufacturer-s directions.