EMISSION CONTROLS AND FUEL SYSTEM 135
Typical 1980 and later AIR system control and
switching valves
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.
c. Check valves — These 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 overheat
ing, one or both of the check valves is prob
ably defective. To check or repkce the valve,
disconnect the hose from the valve and un
screw 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,
repkce the valve. Check each valve in the
same manner.
d. Air injection manifold — The manifold
directs the injected air to each of the cylin
ders. To replace the injection manifold, re
move the check valve from the injection
manifold and unbolt the injection manifold
from the exhaust manifold.
e. Air injection nozzles — The injection
nozzles are located behind each tube of the
injection manifold. The purpose of -the noz
zles is to pinpoint the air injection to the ex
haust valves which maximizes the effect of the
air injection. The nozzles can be simply with
drawn from the exhaust manifold after the in
jection manifold has been removed. In addi
tion to the affbrementioned items, various
hoses, clamps, and tubes are used.
The AIR system used on 1980 California
and 1981-84 engines serves the same func-
tion as the previous system, but is slightly
different in construction and operation. In-
stead of using a diverter valve, this system
uses both an air control valve and an air
switching valve. Both the control and switch-
ing valves are controlled by the Electronic
Control Module (ECM) of the computer con-
trolled emissions system. When the engine is
cold, the ECM energizes an air control sole-
noid, 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 con-
verter permits the converter to more effec-
tively decrease exhaust emission levels. Dur-
ing 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 AND INSTALLATION
Air Pump
1. Remove the valves and/or adapter at the
air pump.
2. Loosen the air pump adjustment bolt
and remove the drive belt.
3. Unscrew the three mounting bolts and
then remove the pump pulley.
4. Unscrew the pump mounting bolts and
then remove the pump.
5.
Installation is in the reverse order of re
moval. Be sure to adjust the drive belt ten
sion after installing it.
Air Control Valve (1980 Calif, and 1981-
82) '
1. Disconnect die negative battery cable.
2. Tag and disconnect the vacuum hose(s)
from the valve.
3. Tag and disconnect the air outlet hoses
from the valve.
4. Bend back the lock tabs and then re
move the bolts holding the elbow to the valve.
5.
Tag and disconnect any electrical con
nections at the valve and then remove the
valve from the elbow.
6. Installation is in the reverse order of re
moval.
Air Switching Valve (1980 Calif, and
1981-84)
The switching valve is replaced in basically
the same manner as the control valve, except
AIR SWITCHING VALVE W
