66f. The idle control valve is faulty;
g. The water temperature sensor is damaged;
h. The vacuum pressure sensor is damaged;
i. The air filter is blocked;
j. The injector leaks;
k. The compression pressure in the cylinder is too low;
l. The intake temperature sensor is damaged.
(3) Diagnosis and Troubleshooting
a. Check high pressure spark, check whether the high pressure spark on the ignition coil high pressure
bus and extension are OK, if the bus spark is week, replace the ignition coil, if the bus spark is OK
while the extension spark is too week, replace the ignition coil also; In addition, excessive spark
plug clearance will influence the starting feature, the clearance of the spark plug shall be adjusted
to normal value (0.8±0.1mm);
b. If there is low fuel pressure, check whether the battery voltage is OK, otherwise it shall be
troubleshot or replaced; check fuel pump check valve for leakage, check fuel filter and fuel pipe for
block, if there are leakage or block, replace or troubleshoot them;
c. If there is leakage for fuel pressure regulator, intake manifold is likely to be mixed with gasoline and
it is hard to start, troubleshoot or replace them;
d. Idle control valve can not be opened to maximum position due to mechanical wear, aging or control
circuit failure, the idle control valve shall be replaced and the control circuit failure shall be troubleshot;
e. If the water temperature sensor data is not accurate, it may cause small injection, check the water
temperature sensor based on the standard data and calibrate the data;
f. There is big time lag for intake pressure temperature sensor that makes it somewhat insensitive at
low speed and result in inaccurate injection, adjustment or replacement shall be made;
g. If the air cleaner filter is too dirty, the air flow resistance is excessively big, resulting in hard start,
as a result of it, the filter shall be replaced.
In a word, there are many factors causing the starting failure of the engine, analysis shall be made based on
the severe conditions of the faults. Generally speaking, check the ignition system first, then check intake
system, fuel system, control system, at last check the cylinder pressure, check the DTC before checking the
trouble. The diagnosis and troubleshooting procedures for starting failure of the engine are shown in (Figure
148).
