6. Unstable idle speed at any time
Table 1-56
S/N Operation Test Results Actions
Yes Remove the trouble
1
Turn the ignition switch to ON. Check if there is trouble
information records with a diagnostic instrument.
No Next step
Yes Replace idle speed actuator
2
Check if the idle speed actuator or the stepper motor
idle speed actuator is locked.
No Next step
Yes Check harness and interface
3
Turn the ignition switch to ON. Connect an adapter
between the ECU and the harness. Check the voltage of
the pin J1-27, J1-43 (signal output end of the intake air
temperature sensor and coolant temperature sensor),
J1-54, J1-33, J1-53, J1-34 (signal output end of the
stepper motor), J1-54, and J1-53 of the ECU. Is the
voltage normal?
No Next step
Yes 8
4
Run the engine at an idle speed. Cut off each cylinder in
sequence. Check if the rotation speed of the engine is
dcreased or fluctuated.
No Next step
Yes Next step
5
Check the fuel injector of each cylinder for normal
operation.
No
Check fuel injector and
harness
Yes Next step
6
Check the resistance of the high voltage wire for each
cylinder. Is the resistance OK?
No Replace
Yes Replace
7 Check the ignition coil for damage or crack.
No Next step
Yes Next step
8 Check the spark plug for normal operation.
No Replace spark plug
Yes Next step
9
Connect the fuel pressure gauge valve. Short-circuit the
pin J1-47 and the pin J1-73 of the fuel bump relay, and
run the fuel pump. Check if the fuel pressure is about
380kPa.
No 13
Yes 12
10
Connect the battery and the fuel injector with a special
connector. With the voltage supply of 12V, check the fuel
injector for normal operation.
No Next step
Yes Next step
11
Clean the fuel injector and check the fuel injector for
normal operation.
No Replace fuel injector
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