KYMCO AK 550, Service Manual

Page: 461 / 461

15.EEC System
AK550
Oxygen Sensor
It uses DC-8-16V Battery Power with 4 pins: one power pin, one heater pin, one
signal output pin and one earthing pin. The sensor is installed to the front pipe of
exhaust pipe to detect the oxygen concentration of exhaust gas for determining if
ECU shall instruct to increase or reduce fuel supply for meeting waste gas
emission standard of environment legislation. When the temperature of exhaust
is less than 350
℃
, the sensing portion can not be activated and there is no signal
output, and ECU will turn on the heater inside sensor to accelerate the
temperature rise of sensor and cause the Oxygen Sensor to work normally. In
normal hours, the impedance of heater is 7.7 +/- 1.2 ohm and can be told with
multimeter. Output of sensor after the engine is warmed up is
A/F <14.7 (mixing ratio too thick) >0.7V
A/F > 14.7 (Mixing ratio too thin) <0.18V
Inspection and adjustment of emission
1.Start the engine and warm up for several minutes engine temperature 80~90
℃
,
connect the diagnostic tool to check the information.
2.Idle speed should be in standard.
3.The emission machine should be connected to the front of the exhaust pipe
measure hole. (Before Catalyst Converter)
4.Standard ： CO:0.3~1.3 %
5.If the figure is out of range, check with the injection relative components.(For
example, injector, fuel pump…etc.)
6.If the problem insist, please check the emission related system and check if
there is any leakage from the cylinder head inlet/outlet valve.
14-9