
6. Idle Speed of Cold Auto Is Not Stable, Tends to Flameout
(1) Symptom of fault:
When the engine operates in cold auto, idle speed is unstable, tends to flameout, after the auto is warmed up, idle speed
becomes normal.
(2) Cause of fault and elimination
a. Water temperature sensor defective, repair or replace it;
b. Idle control valve defective, repair or replace it;
7. Idle Speed of Warm Auto Is Not Stable, or Flameout Occurs
(1) Symptom of fault:
When the engine operates in cold auto, idle speed is normal, after the auto is warmed up, idle speed becomes unstable,
either too low or flameout.
(2) Cause of fault and elimination
a. Idle speed is adjusted too low, adjust to normal;
b. Water temperature sensor defective, repair or replace it;
c. Injector works poorly, or difference between fuel injections is too large, repair or replace it;
d. Water temperature switch or thermostat works poorly, repair or replace it;
e. Check valve damaged, replace it.
8. Idle Speed Is too High for Warm Auto
(1) Symptom of fault:
Engine could operate at normal fast idle speed when the auto is cold, but after the auto is warmed up, it still maintains quick
idle speed, which causes the idle speed to be excessively high.
(2) Cause of fault and elimination
a. Initial idle speed is not adjusted well, readjust it;
b. Pressure of oil passage in the system is high, make adjustment;
c. Water temperature sensor is defective, repair or replace it;
d. Water temperature switch or thermostat fails, repair or replace it;
e. Idle control valve is defective, repair or replace it;
f. Throttle is jammed and cannot be closed tightly, repair or replace it;
g. Fuel evaporation control valve is normally open, repair or replace it;
h. Revolution sensor is defective, repair or replace it;
9. Idle Speed Fluctuation
(1) Symptom of fault:
Revolution of engine fluctuates at idle speed.
(2) Cause of fault and elimination
a. Intake pressure transmitter fails, repair or replace it;
b. Check valve is damaged, replace it;
c. Compatibility of water temperature sensor, water temperature switch and thermostat is not good, and all of them are
defective, repair, adjust, and eliminate it;
d. Oxygen sensor defective, replace it;
e. Poor contact of spark plug, repair or replace it;
f. Idle control valve and its control circuit defective, repair or replace it;
g. Idle switch not closed, repair it.
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Содержание JL481Q
Страница 1: ......
Страница 9: ...5 Fig 3 Components Assembly Drawing of MR479Q MR479QA Engine ...
Страница 10: ...6 Fig 4 MR479Q MR479QA Engine and Its Power System ...
Страница 11: ...7 Fig 5 Assembly Drawing of Engine and Its Auxiliaries MR479Q MR479QA ...
Страница 12: ...8 Fig 6 Electronic Control Fuel Injection System in Engine MR479Q MR479QA ...
Страница 13: ...9 Fig 7 Front view of Engine JL481Q MR481QA ...
Страница 14: ...10 Fig 8 Sectional elevation of Engine JL481Q MR481QA ...
Страница 15: ...11 Fig 9 Electronic Control Fuel Injection System in Engine JL481Q MR481QA ...
Страница 21: ...17 Fig 13 Exterior Feature of JL481Q Engine Power Me N m Torque Pe Kw ge g kwh Fuel Consumption Ratio ...