Lifan 620 Maintenance Manual page 88

S/N
Remove the ignition metal wire from the spark plug. Install
the wire to a normal spark plug. Place the bottom end of
5
the spark plug towards the gound, and then turn to the
engine. Check if the spark is normal.
6 Remove the spark plug. Check the place for dirts.
Check the pressure of the compressor. Standard:
7 1275kPa/300rpm; minimum: 981kPa/300rpm; difference
among cylinders: 98kPa/300rpm.
Install all the removed parts. Release the fuel pressure to
8 0. Install fuel pressure gauge. Check if the pressure is
normal.
Check the ignition time (15°±5°BDTC). The target idle
9
speed is M/T:800±50rpm.
Start the engine for warm-up. After the engine reaches
normal operation speed, measure the voltage between
the pin J1-62 (front oxygen sensor high signal) or J1-06
(front oxygen sensor low signal) of the ECU and the
10
ground. Under the rotation speed of 2000rpm, the
changes between 0V-0.3V and 0.6V-1.0V should be no
less than 5 times, at least one time higher than 0.6V, at
least one time lower than 0.3V, an no higher than 1V.
Check the intake air sensor signal with a diagnostic
11 instrument. (2.0-6.0gm/sec, at idle speed,
7.0-20.0gm/sec, at 2500rpm)
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Table 1-66 (Continued)
Operation
87
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Test Results Actions
Yes Next step
Check ignition coil, giant
No transistor, and their
circuits
No Next step
Repair or replace spark
Yes
plug (standard type)
Yes Next step
Check piston, piston ring,
No air intake valve, valve seat
and cylinder head gasket
Yes Next step
Check as per fuel
No
pressure test method
Yes Next step
No Basic check
Yes Next step
Renew front oxygen
No
sensor
Yes Replace ECU
Check the connector of
the air intake temperature
No
sensor circuit for rust or
looseness.