chrysler technician manual

EMISSION CONTROL SYSTEMS - Exh aust Car Recirculation (EGR) System 25-7
Duty ratio
I , .
ON e-_-m- L--l
T2 L1.
Tl
NOTE
The duty ratio is the ON duration ratio of 16.7 Hz pulse or T2/T1.
The higher the duty ratio, the more mean current flows to the
boost meter. and as a result, the boost meter reads the higher
value.
The smaller is the duty ratio, the boost meter reads the smaller
value.
OFF--- m 1
c 1 -i 1e21002
60 msec. 60 msec.
EGR CONTROL VALVE
Spring
Apply vacuum
Diapliragm
.Valve
To Intake
manifold
Exhaust gas
7EM0012
NOTE
This illustration indicates Non-Turbo models.
7EMOO15
The EGR control valve is a diaphragm that functions
to control the flow of EGR gases by opening and
closing the valve according to the negative pressure
(vacuum) acting upon the partitioned chamber.
When the negative pressure becomes stronger than
the spring force, the valve opens, as shown in the
illustration, and the exhaust gases can flow.
THERM0 VALVE
The therm0 valve functions in response to the temperature of
the engine coolant. thus controlling the negative pressure
acting upon the EGR control valve.
The valve opens at a temperature of 65°C (149°F) or lower, and
closes at 65°C (149°F) or higher.
Valve
Blmetz II
1
7EMOO16