See Figures 1, 2, 3, 4 and 5
This system is used on all 1981-87 2.2L carburetor-equipped engines. Its job is to reduce carbon monoxide and hydrocarbons to required levels. It adds a controlled amount of air to exhaust gases, causing oxidation of the gases and a reduction in carbon monoxide and hydrocarbons.
The air injection system on the 2.2L engine also includes an air switching system. It has been designed so that air injection will not interfere with the EGR system to control NO x emissions, and on vehicles equipped with an oxygen sensor, to insure proper air-fuel distribution for maximum fuel economy.
The vehicles produced for sale in the 50 states pump air into the base of the exhaust manifold and into the catalytic converter body. The Canadian system pumps air through the cylinder head at the exhaust port.
The air injection system consists of a belt-driven air pump, a diverter valve (Canadian engines only), a switch-relief valve, rubber hoses, and check valve tube assemblies to protect the hoses and other components from high temperature exhaust gases in case the air pump fails.Diverter Valve
The purpose of the diverter valve is to prevent backfire in the exhaust system during sudden deceleration. Sudden throttle closure at the beginning of deceleration temporarily creates an air-fuel mixture too rich to burn. This mixture becomes burnable when it reaches the exhaust area and combines with injector air. The next firing of the cylinder will ignite this air-fuel mixture. The valve senses the sudden increase in manifold vacuum, causing the valve to open, allowing air from the pump to pass through the valve into the atmosphere.
A pressure relief valve incorporated in the same housing as the diverter valve controls pressure within the system by diverting excessive pump output to the atmosphere at high engine speed.Switch/Relief Valve
The purpose of this valve, an integral part of all U.S. air injection systems, is two-fold. First of all, it directs the air injection flow to either the exhaust port location or to the down-stream injection point. Second, the valve regulates system pressure by controlling the output of the air pump at high speeds. When the pressure reaches a certain level, some of the output is vented to the atmosphere through the silencer.Check Valve
A check valve is located in the injection tube assemblies that lead to the exhaust manifold and the catalyst injection points on the 50 state engines and to the exhaust port area, through four hollow bolts on the Canadian engines.
This valve has a one-way diaphragm which prevents hot exhaust gases from backing up into the hose and pump. It also protects the system in the event of pump belt failure, excessively high exhaust system pressure, or air hose ruptures.
DIAGNOSIS AND TESTING
The most common problem with the air pump system is air pump noise. It first must be understood that a small amount of rattling or chirping noise comes from an air pump in perfect mechanical condition. It should also be understood that, if the air pump requires replacement, the new pump will be extra noisy until it has broken in. Operate the new pump for 1,000 miles (1,600 km) before condemning it as noisy.
If the air pump belt suddenly becomes noisy, first check that tension is correct. If the belt is slipping, noise will often be the result. Retension the belt or, if it is glazed (with smooth, glassy wear surfaces), replace it, making sure to tension the new belt properly and to readjust it a week or two later.
Check also that the pump rotates freely by removing the belt and turning the pump drive pulley by hand. There is normally some slight roughness and rattling when turning the drive pulley. A frozen pump's pulley will be impossible or extremely hard to turn.
If the car is in generally good tune and mechanical condition, and runs well but exhibits high CO and hydrocarbon emissions, the air pump system may not be supplying air to the catalytic converter (or exhaust manifold on Canadian cars). In this case, the best procedure is to disconnect the outlet hose passing from the switch/relief valve to the converter and check for airflow. If there is no flow at idle speed, and noticeable flow above idle speed, which increases when the engine is accelerated, the air pump system is okay and the problem may be in the oxygen sensor or fuel system. If air does not flow at this point in the system, disconnect the hose at the air pump side of the switch/relief valve and repeat the test. If there is air at this point now, and no vacuum actuating the switch/relief valve, replace it.
Check also that all hoses are free of cracks, breaks and clogs and that they are tightly and fully connected.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Disconnect the hoses at the air pump.
- Disconnect the air and vacuum hoses at the switch/relief valve.
- Remove the air pump drive pulley shield from the engine.
- Loosen the air pump pivot and and adjusting bolts and remove the air pump drive belt.
- Remove the air pump attaching bolts and remove the pump and switch/relief valve as an assembly.
- Remove the switch/relief valve and gasket from the pump.
- Clean both gasket surfaces. Install a new gasket and the relief valve and tighten the mounting bolts to 125 inch lbs. (14 Nm).
- Install the drive pulley on the new air pump and tighten the mounting bolt to 12 inch lbs. (1.3 Nm) or less.
- Position the air pump onto the engine and install the mounting bolts loosely. Loosen the bolts attaching the rear air pump bracket to the transmission housing.
- Install the drive belt onto the air pump drive pulley. Then apply force with a torque wrench to the adjusting bracket. Use 80-100 ft. lbs. (109-136 Nm) to obtain the proper tension. Do not apply force to the pump body! Hold this figure and tighten the bracket-to-transmission bolts to 40 ft. lbs. (54 Nm) maximum.