Page 973 - Workshop Manual - Tunland (2017)

DIAGNOSTICS - ENGINE CONTROL SYSTEM 04-287

ENGINE PHENOMENA DIAGNOSIS TEST 04

WARNING
Some phenomena diagnostic procedures require visual and exterior inspection. Every
time such visual and exterior inspection shall be carried out firstly. Such inspections
can solve one problem and need not further test, and can save precious time.
1 . After receiving a vehicle, shall ask the owner the following problems:

(a) The earliest time that fault appeared.
(b) The engine temperature when the fault occur.
(c) Mileage the vehicle travelled.
(d) Road and habit which the car owner often drives.
(e) The maintenance situation of the car.
(f) The maintenance history of the car.
(g) Has the car been installed additional apparatus? The trouble can be judged tentatively
from the above-mentioned understanding, so as to shorten the time for inspection.
2 . Before perform steps of fault diagnostic precedure according to engine
phenomena, initial inspection shall be performed first.
(a) Confirm that engine fault indicator lamp can work normally. If abnormal, eliminate
trouble of the indicator lamp at first.
(b) Confirm that no engine trouble codes (DTC) are stored in the engine module (ECM).
If they exist, refer to corresponding DTC list to eliminate them. Read the trouble codes
(both present and historical trouble codes shall be recorded) - clear trouble codes –
run (the condition which the trouble occur shall re-appear this time) - read trouble
codes again. Read the trouble code list in the servicing manual, refer to the reason,
influence and elimination method of the trouble. Intermittent trouble codes can't be
ignored.
(c) Use a diagnostic apparatus to check the idling data of heat engine of the electronic
control system and confirm that they are within normal scope.
(d) Confirm that the trouble is present, and the reason for causing the trouble exist.
(e) When maintaining the vehicle, maintaining record, the engine cylinder compression
pressure, the engine machinery timing, and fuel state shall be confirmed.

3 . External visual inspection
(a) Check the connecting condition of ECM ground (earth).
(b) Check whether the connecting pipe of engine vacuum system splits, distorts and is
connected correctly; whether it is flattened or damaged.
(c) Whether the engine oil dipstick, engine oil filling cover are installed correctly.
(d) Check whether ground of the engine (earth) is clean and is fastened firmly.
(e) Check whether the connecting surface of engine gas inlet manifold leak, and whether
the sealing surface between the air throttle and gas inlet manifold is in good condition.
(f) Check whether there is any leakage in the engine fuel system.
(g) Check whether the engine fuel is deteriorated and contains water.
(h) Check whether the socket connectors of engine sensor and actuators are connected
correctly and is fastened firmly.
4 . The accumulated carbon belt which formed on the back of air throttle may directly
lead to a series of problems such as bad idling, unstable idling of engine,