Jeep J-10 Series 1982 Technical & Service Manual page 463

NOTE: Duplicate the procedure for the other air in
jection manifold.
Installation—Eight-Cylinder Engine
(1) Install air injection manifold using replacement
sealing gasket on either side of each inlet port.
(2) Install distribution tube fittings and injection
manifold on exhaust manifold. Tighten fittings with 38
foot-pounds (52 N#m) torque.
(3) Connect air delivery hose to check valve.
NOTE: Duplicate the procedure for the other air in
jection manifold.
DUAL AIR INJECTION SYSTEM
The additional components used with the dual air
injection system are:
• divert and upstream solenoids,
• air control valve,
• coolant temperature switch,
• reverse and two-way delay valves,
• downstream air injection tube.
NOTE: Diverter valve and air pump operation with the
dual air injection system is basically the same as it is
with the single air injection system.
NOTE: The dual air injection system is inter-related
with the feedback system and must be diagnosed in
conjunction with the feedback system. Refer to Chapter
1J-Fuel Systems.
Air Control Circuit Operation
Mr Control Valve
The air control valve is located between the diverter
valve and the air injection manifold. The air control
valve is controlled by vacuum regulated by the upstream
solenoid.
The air control valve directs system air pressure ei
ther "upstream" (into the air injection manifold at
tached to the exhaust manifold) when vacuum is applied
to it or "downstream" (directly into the dual bed mon
olithic-type converter) when vacuum is not applied to it.
The air mixes with the hot exhaust when it enters the
"upstream" input and causes a further burning of the
mixture. This reduces hydrocarbons (HC) and carbon
monoxide (CO) emission to the atmosphere.
During "downstream" operation, the additional air
reacts with hydrocarbons (HC) and carbon monoxide
(CO) in the catalytic converter (rear half) to create car
bon dioxide (CO2) and water vapor and reduce undesi
rable emission into the atmosphere.
EXHAUST SYSTEMS 1K-11
Upstream Solenoid
The air control valve circuit vacuum is controlled by
the "upstream" solenoid (mounted at the rear of the
cylinder head cover). The solenoid is grounded through
the feedback (CEC) system.
When current is allowed to flow through the circuit
and energize the "upstream" solenoid, it opens the air
control valve vacuum to the atmosphere and the air
control valve directs system air pressure "upstream" to
the exhaust manifold.
When the vacuum is allowed to pass through the "up
stream" solenoid (deenergized condition) to the air con
trol valve, air system pressure is directed "downstream"
to the rear half of the dual bed catalytic converter.
Air Bypass Circuit Operation
The controlling vacuum for air bypass is regulated by
the divert solenoid, Open Loop 3 (OL3) vacuum switch
(CEC system) and two-way and reverse delay valves.
Divert Solenoid
The divert solenoid is grounded via the feedback
(CEC) system.
When current flows through the circuit, the energized
solenoid allows atmospheric pressure to displace the
vacuum, which allows the diverter (bypass) valve to
release system air pressure to the atmosphere.
Two-Way and Reverse Delay Valves
Two-way and reverse delay valves are used to prevent
a sudden loss of vacuum during a rapid vacuum decrease
caused by engine acceleration.
Coolant Temperature Switch
The coolant temperature switch is located at the rear
of the intake manifold. This switch controls the up
stream solenoid operation.
NOTE: The coolant switch (dual function) also pro
vides a ground for the intake manifold heater.
Operation
Manifold vacuum should be present at the air control
valve via the upstream solenoid when the coolant tem
perature is lower than 160°F (71°C) (approximately) and
should not be present if the coolant temperature is above
160°F (71°C) (approximately). If the coolant temper
ature is lower than 160°F (71°C) and vacuum is not
present, inspect the vacuum hoses for air leaks and
proper routing. Repair as necessary. If no fault is found,
replace the switch or microprocessor.