Geely EC718 2009 Workshop Manual page 342

2-260 Auxiliary Emission Control JL4G18-D
2.4.3 System Working Principle
2.4.3.1 Heated Type Oxygen Sensor Working
Principle
– Oxygen sensor's sensing element is a porous ceramic tube,
the outer wall surrounded by the engine exhaust and inside
exposed to atmosphere. Sensing ceramic wall is a solid
electrolyte containing an electric heating tube. When the
sensor ceramic tube temperature reaches 350°C (662 ºF ),
it will have a solid electrolyte properties.
– Oxygen sensor's senses ceramic oxygen ion concentration
inside and outside difference and sends it out as a voltage
signal.
– The output voltage level is due to internal electronic
ceramic tubes movement.
– Meet EOBD vehicles self inspect whether the sensor
information is accurate.
–
Heated resistor resistance at room temperature is 2.5-4.9
Ω.
Note
– During the oxygen sensor repair procedure, it is
prohibited to use cleaning agent, oily liquids or
volatile solids.
–
After the replacement of oxygen sensor, apply a layer
of anti-rust oil to oxygen sensor threads to prevent
rust. Oxygen sensors have electrical cables. The
other end of electrical cable is a connector. The
external packaging is anti-fire sleeve. A new oxygen
sensor will be coated with anti-rust oil on the threads,
during installation do not remove these anti-rust oil.
2.4.3.2 Canister Solenoid Valve Working
Principle
1. Canister solenoid valve consists of the electromagnetic
coil, armature and valves so on. Inlet port has a filter.
2. On one hand, air flow through the Canister solenoid valve
is related to ECM output to the Canister solenoid valve
electrical pulse duty cycle; on the other hand, it is related
to the pressure difference between the Canister solenoid
valve inlet port and outlet port. When there is no electrical
pulses, the Canister solenoid valve will be turned off.
3. ECM provides signals to control the Canister solenoid valve
power according to various engine sensor signals, and
indirectly controls the flow of the clean air.
EC718/EC718RV EC715/EC715RV 10/2009
4. When the engine coolant temperature, engine running time
and engine load etc. meet the preset requirements, ECM
will instruct Canister solenoid valve to start working. In the
following situations canister solenoid valve will not work:
• Engine cold start.
• Engine coolant temperature is relatively low.
•
Engine idle.
• Engine load is high.
• Important sensor system faults.
Engine