Toyota Land Cruiser 1988 Repair Manual page 121

To reduce NOx emission, part of the exhaust gases are recirculated through the EGR valve to the intake manifold to lower the maximum
combustion temperature.
Coolant
Engine
Driving Intake
VSV
Throttle Valve Pressure in the EGR EGR Vacuum EGR
Exhaust Gas
Temp. RPM Condition Air Volume Opening Angle Valve Pressure Chamber
Modulator Valve
Below 47"C
OFF CLOSED
Not
(117"F)
-
-
-
-
- -
recirculated
Above
OFF CLOSED
Not
3,500 rpm
-
-
-
-
-
recirculated
Deceleration OFF CLOSED
Not
-
- -
-
recirculated
LOW OFF CLOSED
Not
-
- -
recirculated
OFF CLOSED
Not
-
-
-
recirculated
Above 53"C
Positioned below Not
I
(127"F)
-
-
CLOSED
recirculated
I
Blow
EGR port
I
3,500 rpm
Ex.
(1)
• Pressure con-
OPENS passage
CLOSED
Not
deceleration
Positioned between
LOW
stantly alter-
to atmosphere recirculated
HIGH ON
EGR port and
(2)
nating between
CLO~ES passage
I
EGR R port
HIGH
low and high
to atmosphere
OPEN Recirculated
Positioned above (3)
..
CLOSES passage Recirculated •
OPEN
EGR port HIGH to atmosphere {increase)
.
• Pressure increase ,.... Modulator closes ,.... EGA valve opens ,.... Pressure drops
J
"' EGA valve closes
+-
Modulator opens
E
** When the throttle valve is positioned above the R port, the EGR vacuum modulator will close the atmosphere passage and
open the EGR valve to increase the EGR gas, even if the exhaust pressure is insufficiently low.
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3