COMPUTER CONTROLLED EMISSION CONTROL SYSTEM
[Feed back system]
A prime purpose of this system is to maintain a controlled air fuel ratio, allowing the catalyst to reduce
oxides of nitrogen, hydrocarbons, carbon monoxide and to improve fuel economy simultaneously.
The electronic control module
(ECM)
and the oxygen sensor are provided in this system.
The oxygen sensor mounted on the exhaust manifold monitors the exhaust gas air fuel ratio and signals to
the ECM.
The ECM processes the oxygen sensor signal and controls carburetor air fuel ratio by the operation of the
mixture control solenoid in the carburetor.
Thus the signal of the exhaust gas air fuel ratio sensed by the oxygen sensor is fed back to ECM and the
carburetor air fuel ratio is controlled.
[Electronic control module (ECM)]
The ECM controls the fuel cut system, idle-up system, bowl vent system, EGR system and secondary
throttle valve system, as well as the feed back system. The ECM is located under the glove box of the
instrument main panel. Refer to Fig. 5-l -9.
I
1
* Engine coolant
temperature
*
Engine speed
-
Electronic
control
module
I
I
*
Throttle position
t
(Micro Switches)
I
I
I\-
* Fuel cut solenoid valve
-44
* Engine room
-
* Vent solenoid valve
tempe.rature
*
Idle-up actuator (TWSV)
*
Electric load
*
Secondary throttle valve (VSV) ,
_
~
r
*
Mixture control
solenoid valve
*
Barometric
pressure
+
ECM supply
voltage
*
Gear position
Fig.
5-l-8
Computer con trolled emission
con trot s ys tern
5-
10
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