115
The outside of the ceramic body (b) is exposed to the exhaust emission and the inside (a) is exposed to
ambient atmosphere. The working principle of sensor is as following: When the temperature is over 300
℃，
the ceramic material will be the conductor of ferric oxide. Under this condition, if the percentage
content of the oxygen in the two sides of sensor (a, b) are not the same, the voltage difference will occur in
the two sides. The difference of measured oxygen content in two ambient (at the side of air and at the side
of exhaust) tells ECU that the remainin oxygen content in the exhaust is not propriate for ensuring the
combustion with no harmful exhaust products produced
The ceramic material under 300
℃
is non-linear, therefore the sensor doesn’t send the useful signal.
ECU has a special function, i.e. stop adjusting the mixture during engine warming (open loop operation).
The sensor is equipped with a heating unit (4) to reach the operation temperature as soon as possible.
When the current flows over the heating unit, it shortens the time for ceramic becoming the conductor of
iron and may have the sensor installed in the relatively rear area of exhaust pipe.
λ
sensor inspection
：
To check all sensors and actuators, injection system ECU has a complete high-efficiency self-diagnosis
system. When failure occurs, the warning light will turn on.
Warning
：
Before checking exhaust emission
or
λ
sensor, check
：
1.
The warning light should go out, or use CHECK—UP1 diagnosis instrument to determine the failure and
adjust it for correct operation.
2.
Little difference exists between the working parameter showed on CHECK—UP1 and the actual engine
condition.
3.
The fuel pressure should be the specified value (0.9—1.0bar). When the pump stops, no sudden pressure
drop occurs (pressure sealing).
4.
When the fuel pump operates, CHECK—UP1 performs to stop engine and recycle oil circuit. Injection
system ECU may adjust automatically, therefore it may compensate for the system failure caused by the
engine degradation. According to the signal of
λ
sensor (figure 177)
，
in the precondition of without any
exterior interference, the mixture can be automatically adjusted to the perfect value electronically.
·
When engine is idling with no electrical load and
λ
controlling is functioning(close loop)
，
select
LAMBDA CHECK to check if the slipping ruler on the CHEC K—UP1 diagnosis tool is in the middle of
two base points .
7.
Catalytic converter
Fig.177
Содержание JNSZ1600DL
Страница 22: ...21 ENGINE CONFIGURATION VIEW AND SECTIONAL VIEW Fig 22 Fig 23...
Страница 111: ...120 Fig 181...
