Page 526 - Foton Workshop Manual - Tunland (AT)

04-380 DIAGNOSTICS - ENGINE CONTROL SYSTEM

HIGH IDLE SPEED (IDLE SPEED IS NOT WITHIN THE SPECIFIED

VALUE)

Fault phenomenon Diagnosis logic Possible reasons

• Intake system leakage • Too high fuel pressure
04 • Turbocharger leakage • Intake pipe fault
• Wrong mixture ratios • Turbocharger leakage

High idle speed (idle speed is • Throttle body • Wrong mixture ratios
not within the specified value) • Injector • Electronic throttle fault
• Injector • Intake mass flow sensor
• Intake mass flow sensor fault
• ECM • ECM

NOTICE

When the motor idling runs, if the mixture gas distribution disorders, intake system
leaks or some cylinder doesn't work due to the ignition system failure, it will cause
the default of no idle, too high idle speed, unstable idle or poor idle and other defaults.

Diagnosis Procedure

1 . Check the engine data

(a) Ignition switch: OFF.
(b) Connect the diagnosis tool with the fault diagnosis connector (16 pins) on the lower
left of the dashboard.
(c) Ignition switch: ON, and start the diagnostic tool.
(d) Read the motor data shown on the diagnostic tool.

Check whether the data flow is normal or not.
YES>To step 2.
No >Maintenance related faults.

2 . Perform visual and external check
(a) Observe the rotation status and shaking degree of the engine
(b) At the same time, observe the swing range of the engine tachometer indicator, and
check whether it deviates from the idle target value.
(c) Observe whether it is normal idle jitter or load idle jitter. (Turn on the air conditioner,
light, hanging gear and turn the steering wheel etc.)
(d) Whether the external parts of the motor are normal or not; whether the wire connector
looses or not.
(e) Whether it has the four phenomena of leakage of fuel, water, gas and electricity.
(f) Whether the exhaust pipe has the phenomena of “chug, chug” (indicating poor
combustion), black smoke, raw fuel smell and other abnormal phenomenon.

Is the inspection result normal?
YES>To step 3.
No > Exclude the problem and confirm that the phenomenon no longer exists.

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