See Figures 1, 2, 3 and 4
Two different systems of air injection have been used on the Corvette. The system used up to and including 1980 (except 1980 Calif.) consists basically of the following components:
- The air injection pump draws fresh, outside air into the pump, pressurizes the air, then delivers the air to the remaining system components.
- The diverter valve (sometimes called an anti-backfire valve) receives pressurized air from the air injection pump. The diverter valve is controlled by manifold vacuum. During deceleration, manifold vacuum increases sharply. This vacuum increase causes the diverter valve to divert the air from the air injection pump to the atmosphere, thereby preventing backfiring through the exhaust system. If vacuum is evident at the diverter valve vacuum hose at idle, yet the engine still backfires only during deceleration, replace the valve. Replacement is a simple matter of disconnecting the vacuum line from the valve and unbolting the valve from the injection pump.
- The check valves (one per side of the engine) prevent the entrance of hot exhaust gasses into the AIR system. If AIR pump and hose life is short due to overheating, one or both of the check valves is probably defective. To check or replace the valve, disconnect the hose from the valve and unscrew the valve from the injection manifold assembly. Blow into each side of the valve: air should pass only in one direction; if air passes through the valve in both directions, replace the valve. Check each valve in the same manner.
- The air injection manifold directs the injected air to each of the cylinders. To replace the injection manifold, remove the check valve from the injection manifold and unbolt the injection manifold from the exhaust manifold.
- The air injection nozzles are located behind each tube of the injection manifold. The purpose of the nozzles is to pinpoint the air injection to the exhaust valves which maximizes the effect of the air injection. The nozzles can be simply withdrawn from the exhaust manifold after the injection manifold has been removed. In addition to the aforementioned items, various hoses, clamps, and tubes are used.
The AIR system used on 1980 California and 1981-82 engines serves the same function as the previous system, but is slightly different in construction and operation. Instead of using a diverter valve, this system uses both an air control valve and an air switching valve. Both the control and switching valves are controlled by the Electronic Control Module (ECM) of the computer controlled emissions system. When the engine is cold, the ECM energizes an air control solenoid, which allows air to flow to the air switching valve. The air switching valve is then energized which directs the air injection to the exhaust manifolds. When the engine warms, the ECM de-energizes the air switching valve, which changes the point of air injection from the exhaust manifolds to the catalytic converter. The extra air at the converter permits the converter to more effectively decrease exhaust emission levels. During deceleration and wide open throttle operation, air is directed to the air cleaner.
Operation of the air pump, check valves, and manifolds remains the same as the 1979 and earlier system.
REMOVAL & INSTALLATION - Air Pump
See Figures 5 through 9
- Remove the valves and/or adapter at the air pump.
- Loosen the air pump adjustment bolt and remove the drive belt.
- Unscrew the three mounting bolts and then remove the pump pulley.
- Unscrew the pump mounting bolts and then remove the pump.
- Installation is in the reverse order of removal. Be sure to adjust the drive belt tension after installing it.
Air Control Valve (1980 California and 1981-82 Vehicles)
See Figure 10
- Disconnect the negative battery cable.
- Tag and disconnect the vacuum hose(s) from the valve.
- Tag and disconnect the air outlet hoses from the valve.
- Bend back the lock tabs and then remove the bolts holding the elbow to the valve.
- Tag and disconnect any electrical connections at the valve and then remove the valve from the elbow.
- Installation is in the reverse order of removal.
Air Switching Valve (1980 California and 1981-82 Vehicles) See Figure 10
The switching valve is replaced in basically the same manner as the control valve, except that it is mounted to a bracket on the A/C compressor.