Lifan 620. Manual - part 6

 

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Lifan 620. Manual - part 6

 

 

(1) Function:

 To provide information on coolant temperature. To provide water temperature signal 

for the ECU, and to control ignition timing and fuel injection pulse width at start, idle speed, and 
normal operation. 

(2) Structure and principle: 

Made by a thermistance with NTC. The resistance value will 

decrease with the increase of the coolant temperature (not a linear relation). The thermistance 
with NTC is installed within a copper sleeve. With a voltage division circuit, the resistance value of 
the thermistance is converted into a changing voltage and then provided to the ECU, and then the 
change of water temperature can be monitored (internal structure of ECU). 

(3) Connection of wiring diagram (Fig. 1-6) 

 

 

KS1-7 

(1) Function:

 To provide engine knock information for the ECU for knock control. 

(2) Structure and principle: 

As a vibration acceleration sensor, installed on the cylinder block of 

the engine. The sense element of the sensor is a piezoelectric element. The vibration of the 
cylinder block of the engine can be transferred to the piezoelectric crystal through the mass block 
within the sensor. Under the mass block vibration pressure, voltage will be produced at the two 

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(5) Installation notes: 

The tightening torque for installation is 20±5N·m. 

 
5. Oxygen sensor

   

(Fig. 1-8) 

 

Fig. 1-8 

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(1) Function: 

To provide the information that whether oxygen in the cylinder is too high after the 

fuel is burned with the air in the cylinder. With this information, the ECU can carry out closed loop 
control for the fuel ration. Therefore, the three main toxic elements (HC, CO, and NOX) of the 
engine exhaust can be best converted and purified in the three-way catalytic converter. 

(2) Structure and principle: 

The sense element of the oxygen sensor is a ceramic pipe with holes 

 

 

Fig. 1-9 

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(4) Trouble diagnosis: 

The ECU will monitor the sensors, actuators, power amplifying circuit and 

detecting circuit. In case of any of the following situations, like unreliable battery voltage, 
unreliable air intake manifold absolute pressure singal, unreliable engine coolant temperature 
signal, fuel injector driving stage trouble, incorrect oxygen sensor trouble mark level, and fuel 
ration closed loop control closed, the fuel ration will be confirmed according to the basic fuel 
injection time stored in the ECU. 
(5) Installation notes: 

The tightening torque of the oxygen sensor is 50~60N·m. Apply anti-rust 

oil to the renewed oxygen sensor to prevent difficult removal due to rust. 

(4)

Pin 

J1-22 Trouble 

indicator 

J1-23 Not 

used 

J1-24 Throttle 

position 

J1-25 

Not used 

J1-26 

Not used 

J1-27 

Intake air temperature

J1-28 

Crankshaft 58 teeth signal 

low 

J1-29 Not 

used 

J1-30 Not 

used 

J1-31 Engine 

trouble 

indicator 

J1-32 Ignition 

switch 

J1-33 

Idle speed phase B 

output positive 

 

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