Repair Manual

IGNITION AND INJECTION
17
17 - 20
OXYGEN SENSOR ( Lambda )
The oxygen sensor (Lambda) is fixed on the primary down tube, in front of the catalytic
converter. Its purpose is to determine the oxygen content of the exhausted gases; this
oxygen content value depends upon the dosing of the air-fuel mixture. The sensor consists of:
1 - Ceramic element (ZrO
2
)
2 - Protection tube with 3 slits
3 - Threaded metallic body
4 - Protection case
5 - Electric connection
6 - Electric element for rod heating
The functioning mode of the sensor is based upon the ceramic property of leading the
oxygen ions, at temperatures within 300 – 800 °C. The external area of the ceramic
element is in contact with the burned exhausted gases while its internal area is in contact
with the fresh air. As a consequence there will be a voltage signal between these two
ceramic areas; this signal will be transmitted to the electronic control unit (pin 9 – pin 10).
According to the size of this signal, the computer will control the ignition and injection
systems in order to obtain a value ë = 1,essential condition for catalyst operation under
optimal conditions, namely an efficient de-pollution.
The setting method in closed loop with Lambda rod is according to the following diagram:
Admission
Injector
Evacuation
Rich (poor) fuel mixture
Oxygen sensor
Computer
Reference voltage
5
43
1
62
DESCRIPTION OF THE SYSTEM
vnx.su