Exhaust Gas Recirculation System - Jeep J-10 Series 1982 Technical & Service Manual

EXHAUST GAS
RECIRCULATION (EGR)
SYSTEM
Page
EGR CTO Vilve 1J-75
EGR Delay Valves U-77
EGR Vacuum Dump Valve 1J-76
CARBURETOR
FUEL SYSTEMS 1J-73
Page
EGR Valve 1J-73
General 1J-73
Thermal Vacuum Switch (TVS) 1J-76
EXHAUST
CROSS FLOW
EGR VALVE
ADAPTER
EGR
VALVE
90750
GENERAL
The EGR system used on all Jeep vehicles reduces the
production of oxides of nitrogen (NOx) by introducing a
metered amount of exhaust gas into the combustion
chambers. Exhaust gas is inert (will not burn), therefore
combustion temperature is lowered and less NOx is pro
duced at the lower combustion temperature.
EGR action does not occur until the engine coolant
temperature has reached a calibrated level and the en
gine load is sufficient to permit proper EGR operation
(figs. 1J-139.140 and 141).
The EGR coolant temperature override (CTO) valve
prevents EGR action until engine coolant temperature
reaches a calibrated level, and the back-pressure sensor
permits EGR action only at increased engine loads, im
proving driveability.
Depending on model applications, the following com
ponents may be used either seperately or together. The
Thermal Vacuum Switch (TVS) is located in the air
cleaner and is controlled by air cleaner air temperature.
The TVS controls the vacuum passage between the EGR
CTO valve and the EGR valve. At air temperatures
below the calibrated value, the TVS limits the effects of
vacuum on the EGR valve. This prohibits EGR valve
operation and improves cold engine driveability. The
EGR Vacuum Dump Valve is connected between the
EGR vacuum source and the EGR valve. At the cali
brated vacuum level, the vacuum to the EGR valve is
interrupted, thereby preventing EGR operation. This
valve is used to eliminate the EGR function at relatively
low intake manifold vacuum levels.
Rg. 1J-139 EGR System—Four-Cylinder Engine—Typical
EGR VALVE
The EGR valve mounts on a spacer plate located be
neath the carburetor for four-cylinder engines, on the
side of the intake manifold for six-cylinder engines and
on a machined surface at the rear of the intake manifold
on eight-cylinder engines. Exhaust gas enters the intake
manifold via the cross flow cast into the cylinder head
on four-cylinder engines, is drawn from the center of the
exhaust manifold via a flexible tube on six-cylinder en
gines and from the exhaust crossover passage on eight-
cylinder engines.
EGR PORTED
VACUUM
FRONT
O
EGR VALVE
(BACK-PRESSURE
SENSOR INTEGRAL)
INNER EGR
SPORT CTO
VALVE
42014
Hg. 1J-140 EGR System—Six-Cylinder Engine—Typical