Engine Sensor Testing; Oxygen Sensor; Temperature Sensor - KNOVA KN 8056 Manual

Diagnosis of automotive Troubles
A. Start the engine of the automobile to achieve a
rotation speed of 3000 RPM. So far as a GM
automobile is concerned, set the rotary switch
to the DWELL and select 6CYL.
B. When the automobile is operating in a short fuel
state or in a long fuel state, the dwell of the
meter should be displayed between 10º and 50º.
(2) Fuel Injector Resistance Testing (see figure 15)
The testing method is similar to that of the
resistance of an ignition coil.
A. Cut the electric link off the injector.(Refer to the
servicing handbooks of various kinds of
automotive manuals for the detailed position.)
B. Connect the red and black test lead probes to
the two ends of the injector. The general normal
resistance is less than or equal to 10Ω.
J. Engine Sensor Testing (see figure 16)
Long
figure 16
Fuel
Red
Ground
Black
To be adapted to the provisions for low injection
and fuel saving in the early period of the eighties,
the computercontrolled regulators were installed in
the automobile and the sensors provided the
computer with some data required. The multimeter
is an effective tool for the detection of the
operation of a sensor.

1.Oxygen Sensor

The oxygen sensor is used to test the oxygen
content in the exhaust, giving rise to an appropriate
voltage or resistance. A low voltage (high resistance)
means a too high oxygen content in the exhaust,
while a high voltage (low resistance) means a too
low oxygen content. The computer regulates the
ratio between the air and the fuel according to the
high or low voltage. There are normally two types
of oxygen sensors: the zirconia and titania sensors.
(Refer to the different external properties of the
two types for the details.)
Fuel injector
Red
Black
figure 15
Short
Fuel
If the sensor has a 1- or 3-lead outlet,
the ground terminal is its shell.
If the sensor has a 2- or 4-lead outlet,
the ground terminal is its special wiring.
Testing Procedure:
(1) Move the oxygen sensor out of the automobile.
(2) Set the rotary switch to 200Ω. As prompted
at the LCD connect terminal, insert the red test
lead into the Ω terminal and the black one into
the COM terminal.
(3) Connect the black test lead probe of the meter
to the ground terminal (i.e. cold end) of the
sensor.
WARNING
• If the sensor has a 1- or 3-lead outlet,
the ground terminal is its shell.
• If the sensor has a 2- or 4-lead outlet, the ground
terminal is its special wiring
(4) Connect the red test lead probe of the
multimeter to the signal terminal (i.e. hot end)
of the sensor.
If the sensor has more than 3 leads, what is
used in the automobile is a heat oxygen sensor,
which has 2 hot ends. Refer the positions of
the hot ends in various kinds of automotive
manuals.
At this time, connect the red and black test
lead probes respectively to these two hot
ends. Compare the readings with the
specifications in the operation manual provided
by the manufacturer.
The zirconia sensor is tested with the 2VDC.
As prompted at the LCD connect terminal,
insert the red test lead into the V terminal
and insert the black test lead into the COM
terminal.
The titania sensor is tested with the 200kΩ.
As prompted at the LCD connect terminal,
insert the red test lead into the Ω terminal
and insert the black test lead into the COM
terminal.
Secure the sensor with a table vice, light up
the propane burner and add a heat sensor
terminal. Make its temperature about 660ºF
and exhaust the oxygen from the sensor, when
the readings can be obtained:
The zirconia sensor has a voltage of 0.6 V
or more.
The titania sensor has a resistance of about
1Ω.
Move the burner away for heating, when the
reading can be obtained:
The zirconia sensor has a voltage of 0.4 V
or more.
The titania sensor has a resistance of about
4 kΩ.
WARNING
• In testing, the readings will vary with the
heating temperatures.
2. Temperature sensor (see figure 17)
The temperature sensor changes the output
resistance through the changes in peripheral
temperatures. The hotter the sensor is, the lower
the resistance becomes. The temperature sensor
is generally used in engine braking, air ventilation,
flow, fuel temperature and other equipment.
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