Lifan 620 - With Normal Start, Unstable Idle Speed During Warm-Up

Table 1-72 (Continued)
S/N Operation Test Results Actions
Yes
Remove the mechanical
troubles for the engine
7
Check the pressure for each cylinder of the engine.
Are they great different?
No Next step
Yes Next step
8
Check if the ignition sequence and timing of the
engine can meet with the standards.
No
Check and repair ignition
timing
Yes Diagnosis help
9
Connect the electronic injection system adapter.
Turn on the ignition switch. Check the power supply
of the pin 12#, 13#, 44#, 45#, 63#. Check the
grounding of the pin 3#, 51#, 53#, 61#, 80#. Are
they OK?
No
Check and repair relevant
line
7. With normal start, unstable idle speed during warm-up
Common trouble location:
1. Fuel with water; 2. Coolant temperature sensor; 3. Spark plug;
4. Throttle body and idle speed by-pass air way; 5. Intake air way;
6. Idle speed regulator; 7. Mechanical part of the engine.
Diagnosis Flow
Table 1-73
S/N Operation Test Results Actions
Yes
Check and repair air
intake system
1
Check the air filter for blockage and the intake air
way for leakage.
No Next step
Yes Next step
2
Check the spark plug for each cylinder. Check if its
model and gap can meet with starndards.
No Adjust or replace
Yes Wash relevant parts
3
Remove the idle speed regulator. Check the throttle
body, idle speed regulator, and idle speed by-pass
air way for carbon deposition.
No Next step
Yes Replace sensor
4
Disconnect the coolant temperature sensor, and
start the engine. Check the engine under warm-up
for unstable idle speed.
No Next step
94
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