Page 142 - Foton Workshop Manual - Auman EST-M
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DI - 88 Diagnosis - Diagnosis-fault diagnosis of electronic and electrical parts
Overhigh idling speed
Failure phenomenon list
Failure phenomenon Possible reason Failure elimination
● Check the air filter and intake pipeline
1. Excessive air intake flow at idling
● Check the intake manifold pressure
speed
sensor
● Check if the oil metering cell is
Overhigh idling speed (above its broken
specified value) ● Check if the fuel pressure sensor is
2. Excessive fuel injection capacity
broken
● Check whether the fuel injector is
damaged or its relevant harness is faulty
3. ECM failure ● Replace ECM
Caution
When the engine runs at idling speed, if the failure of individual cylinder is caused by dispensing
disorder of mixed gas, air leakage of air intake system or faulty fuel supply system, it will lead to no idle,
overhigh idling speed, unstable idle and poor fast idle, etc.
Diagnosis procedure
1. 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 2.
NO> check and repair relevant failure
2. Check the oil supply system of generator
a. Check if the high pressure pump leaks or is stuck.
b. Check if the oil pipe is broke and if the joint is secured and reliable.
c. Check if the oil metering cell and harness are ok.
d. Check the fuel pressure sensor (refer to Chapter DI diagnosis- engine electronic control fault diagnosis–fuel
pressure sensor failure)
Check if the result is ok?
Yes>go to Step 3.
NO> check and repair relevant failure.
3. Check the injector and circuit
a. Check the injector (refer to Chapter DI diagnosis- engine electronic control fault diagnosis–injector circuit
failure)
DI-088
