Page 140 - Foton Workshop Manual - Auman EST-M

DI - 86 Diagnosis - Diagnosis-fault diagnosis of electronic and electrical parts

Unstable idling (suddenly high or low)
Failure phenomenon list

Failure phenomenon Possible reason Failure elimination
1. Oil brand is different from the
● Replace the specified oil.
specified one
● Check if the high pressure oil pump
supplies sufficient oil rail pressure
● Check if the oil metering cell is
broken
2. Oil supply system failure ● Check if the low pressure oil-way
supplies smoothly, injector is stuck, high
pressure oil pipe cracks, etc.
● Check if the fuel pressure sensor is
broken
● Check the air filter and intake pipeline
Unstable idling of engine 3. Air intake system failure ● Check the intake manifold pressure
sensor
● Check the crankshaft/camshaft
4. Incorrect operation time sequence position sensor is ok
● Check if the connector and wire are ok
● Check the fuel injection driving wire
(with connector) for broken or short
circuit.
5. Injector failure ● Check if the high pressure oil pipe
leaks
● Check if the injector is broken or there
is carbon deposit
6. ECM failure ● Replace ECM
Diagnosis procedure
1. Check the engine oil

a. Check if the engine oil meets the requirement
Check if the result is ok?
Yes>go to Step 2.

NO>replace with the specified engine oil.
2. Check the engine air intake system

a. Check if the intake pipe is broken and if the connection leaks.
b. Check if the air filter is clean, not blocked and free of foreign matters.
c. Check if the intake manifold pressure sensor is ok (refer to Chapter DI diagnosis- engine electronic control
fault diagnosis–intake manifold pressure/temperature sensor failure)
Check if the result is ok?

Yes>go to Step 3.
NO> check and repair relevant failure.

DI-086