Exhaust Gas Recirculation (Egr) System - Jeep 1979 CJ-5 Technical & Service Manual

FUEL SYSTEMS 1J-37
P i p
General 1J-37
m j i K O N
(mm)
E l l CTO Switch 1J-39
EGR Valve 1J-38
GENERAL
The EGR system used on all Jeep vehicles reduces the
formation of oxides of nitrogen (NOx) by introducing a
metered amount of exhaust gas into the combustion
chambers. Exhaust gas is inert (will not burn), so com-
bustion temperature is reduced. Less NOx is produced a t
lower combustion temperature.
EGR does not take place until engine operating tem-
perature has reached a preset level and engine load is
sufficient to permit proper EGR operation.
Jeep vehicles use three different types of EGR sys-
tems (fig. 1J-68, 1J-69 and 1J-70). The EGR system
without back pressure sensor; EGR system with in-
tegral back pressure sensor; EGR system with exter-
nal, non-integral back pressure sensor.
Fig. U-68 Ell System—Six-Cylinder—Typical
The EGR CTO switch prevents EGR action until en-
gine temperature reaches a preset level, and the back-
pressure sensor, if equipped, permits EGR action only a t
increased engine loads, improving driveability.
C A R B U R E T O R E G R P O R T
4 1 2 6 3 A
Fig. 1 J - 6 9 EGR System—Eight-Cylinder—Typical
C A R B U R E T O R E G R P O R T
A J 4 1 2 6 3 B
Fig. 1J-70 EGR Spin—Eight-Cylinder—with External,
Non-Integral Back-Pressure Sensor
Depending on model applications the following com-
ponents may be used either seperately or together. The
Thermal Vacuum Switch is located in the air cleaner and
is controlled by air cleaner air temperature. The TVS
controls the vacuum passage between the EGR-CTO
switch and the EGR valve. At temperatures below the