DESCRIPTION
The Air Injection Reactor (A.I.R.) system is used on all engines except some 2.0L 4-cylinder engines. This system is designed to reduce hydrocarbons (HC) and carbon monoxide (CO) emissions.
This is accomplished by injecting air into either the exhaust port of the cylinder head, exhaust manifold or catalytic converter. The A.I.R. system operates at all times and will by-pass air only for a short period of time during deceleration and at high speeds.
The air management valve performs the by-pass and diverter function. The check valve protects the air pump from damage by preventing a backflow of exhaust gases.
Schematic of a Typical Air Management System. Scheme 50
AIR PUMP
The air pump is a belt driven type vane pump, located at the front of the engine. The pump supplies clean air to the A.I.R. system.
The system uses air from the air pump to cause further oxidation (burning) of HC and CO before these gases are discharged from the tailpipe.
DECELERATION VALVE
This valve is used on some engines to prevent backfiring in the exhaust system during deceleration. This valve is normally closed, but opens when sudden deceleration increases vacuum to a point of overcoming internal spring pressure.
This allows additional air into the intake manifold to prevent overly rich mixtures from entering the combustion chambers. Air trapped in the chamber above the vacuum diaphragm will bleed, at a calibrated rate, through the delay valve portion of the integral check and delay valve.
This reducing vacuum acts on the diaphragm. When the vacuum load on the diaphragm matches spring load, the valve assembly closes. This shuts off air to the intake manifold.
DIVERTER VALVE
The diverter valve is also used to prevent backfire in the exhaust system during sudden deceleration. The valve senses sudden increases in intake manifold vacuum causing the valve to open. This allows air from the air pump to pass, through the valve and silencer, to the atmosphere.
A pressure relief valve controls pressure within the system by diverting excess pump outlet air (developed at higher engine speeds) to the atmosphere through the silencer.
CHECK VALVE
The check valve prevents the backflow of exhaust gases into the air distribution system. The valve prevents backflow when the air pump by-passes at high speeds, extreme engine loads, or in case the air pump malfunctions.
ELECTRIC AIR CONTROL VALVE
This valve combines 3 separate functions into a single valve. It provides normal diverter valve function and pressure relief by diverting air into the engine air cleaner when system pressure exceeds a predetermined value.
Since the valve utilizes a solenoid, the valve can be electrically controlled to divert air under any desired operating mode.
When the solenoid is energized, the valve will perform like a standard diverter valve. When the solenoid is de-energized, the solenoid causes air to divert during all operating modes.
ELECTRIC AIR SWITCHING VALVE
The air switching valve is a spring actuated 2-way valve. This valve is located in series between the air control valve and the exhaust system.
When the solenoid is de-energized, a vacuum is applied to the diaphragm chamber to provide air flow to the exhaust ports.
When the solenoid is energized, vacuum to the diaphragm chamber is blocked and the chamber is vented to the atmosphere. This allows the spring to open the port to the catalytic converter and close the port to the engine.
ELECTRIC AIR CONTROL/ELECTRIC AIR SWITCHING VALVE
The electric air control/electric air switching valve (EAC/EAS) combines both diverter function and the air switching function into one integral valve.
In addition to normal diverter valve function, this valve can be electronically controlled to provide divert air under any driving mode.
The second section of the valve can be electronically controlled to provide the air switching function. This is to provide direction for air not diverted to the air cleaner.
Sectional View of EAC/EAS Valve. Scheme 51
COMPONENT TESTING
Note. For Air Management System Function Check, Electric Air Control/Electric Air Switching Valve check and Electric Diverter Valve check, see DIAGNOSTIC CHARTS in COMPUTER COMMAND CONTROL article.
- Inspect check valve whenever working on A.I.R. system. If pump was inoperative and had signs of exhaust gases reaching pump, a failed check valve would be indicated.
- After detaching valve, blow though it in direction of flow to cylinder head, then attempt to suck back through direction of flow. Replace valve if it allows airflow against direction of flow.
- Accelerate engine to approximately 1500 RPM and observe air flow from hoses. If airflow increases as engine is accelerated, pump is operating properly. If it does not increase, or is not present, proceed to next step.
- Check for proper pump belt tension, leaky valves, seized pump, improperly routed hoses or disconnected hoses.
Note. Do not oil air pump. The air pump system is not completely noiseless.
EXCESSIVE NOISE
- Loose drive belt.
- Seized air pump.
- Leaking hose or hoses.
- Diverter and/or by-pass valve failure.
- Loose pump mounting bolts.
- Internal pump damage.
NO AIR SUPPLY
- Loose drive belt.
- Leak in hoses or tubing.
- Diverter or by-pass valve failure.
- Check valve failure.
- Internal pump malfunction.
EXHAUST BACKFIRE
- Engine not tuned to specifications.
- Engine vacuum leaks.
- Faulty diverter valve or check valve.
- Electric air switching valve or air control valve not switching air pump discharge to air cleaner on start or quick deceleration.
POOR GAS MILEAGE
- Air pump output not shifting to catalytic converter upon signal from TVS.
- Faulty electrical and/or vacuum circuits.