Moteurs Baudouin 12M26 Series, Operation & Maintenance Manual

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Operation & Maintenance Manual for 12M26 Series Gas Engine
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2.2.9. Oxygen sensor (UEGO)
Figure 2-11 Oxygen sensor
The oxygen sensor is used to measure the oxygen content in the exhaust gas and convert the
measured value into electrical signal and sent the signal to ECU. ECU adjusts the fuel supply
amount by adjusting the injection pulse width according to the air-fuel ratio set in the pulse chart,
achieving the closed-loop control against the engine.
Precautions for oxygen sensor are as follows:
● The installation position of the oxygen sensor is very important for the correct operation of the
system, so the oxygen sensor must be installed in strict accordance with the requirements.
● The oxygen sensor should be installed at a distance of 3 to 5 times the exhaust pipe diameter
from the turbocharger outlet.
● The oxygen sensor may not be installed at or after the exhaust pipe bends.
● In order to prevent the oxygen sensor screw thread from being sintered on the exhaust pipe and
causing the difficulty in disassembly, molybdenum disulfide should be applied evenly on the
threads of the oxygen sensor.
● If the vehicle is equipped with an exhaust brake, the oxygen sensor should be installed at
15cm-25cm downstream of the exhaust brake and should be placed as close as possible to the
turbocharger.
● The wire harness and connector of the oxygen sensor should be far away from the exhaust pipe,
eliminating the possibility of sintering.
● The height of the oxygen sensor’s screw base welded to the exhaust pipe should be less than
10mm, and the length of the oxygen sensor’s probe into the exhaust pipe should be no less than
13mm.
● If the oxygen sensor is involved with failure or poor contact of wire harness and connector,
high gas consumption and instable idling speed may be caused.
● The oxygen sensor should be installed on the side of the exhaust pipe (circumferentially) away
from the engine.
● The oxygen sensor that meets the above conditions should be placed as close as possible to the
turbocharger.
● The angle between axis of the sensor and the direction of gas flow is from 90°+15°to- 30°
（ avoid the direction of gas flow faced to measurement hole.