Page 568 - Foton Workshop Manual - Tunland (AT)

04-422 DIAGNOSTICS - ENGINE CONTROL SYSTEM

IN LOW IDLE OR HIGH IDLE SPEED,THE ENGINE IS UNSTABLE

IDLING

Fault phenomenon Diagnosis logic Possible reasons

• Injector fault
04 • Leakage in the intake
system
• Low fuel pressure
• Air filter blocked
• Coolant temperature sensor
fault
• Injector
• Intake mass flow sensor
In low idle or high idle speed, • Fuel system fault
the engine is unstable idling • Intake system
• Electronic throttle fault
• ECM
• Block in fuel filter
• Incorrect injection timing
• Intake heater fault
• Too low the cylinder
compression pressure
• Exhaust system blocked
• ECM fault

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 . Check the intake system
(a) Check whether air filter is blocked.
(b) Check whether pipe of the intake system leaks.
(c) Check whether turbocharger can work properly.
Is the inspection result normal?

YES>To step 3.
No >Maintenance related faults.

3 . Check the throttle valve

(a) Slightly step the accelerator pedal and start the motor.

Page 568