Maintenance Manual for J2 Sedan
Electronic Control System
of Engine
232
Trouble phenomenon 6: Normal start-up but unstable idling at any time
General trouble position:
1.
Poor quality of fuel; 2.Fuel injector ; 3.Spark plug; 4.Throttle body and idle bypass air passage;
5.Intake passage; 6.Idle adjustor (step motor ); 7.Ignition timing; 8.Spark plug; 9.Mechanical part
of engine.
General diagnosis procedure:
No.
Operating Steps
Detection
Results
Subsequent Steps
Yes
Repair the intake
system
1
Check air filter for blockage and intake passage for leakage.
No
Next step
Yes
Wash or replace
2
Check idle adjustor for sticking.
No
Next step
Yes
Next step
3
Check the spark plug of each cylinder to observe whether its model
and gap are in compliance with the specification.
No
Adjust or replace
Yes
Wash
4
Check air throttle body and idle bypass air passage for carbon
deposit.
No
Next step
Yes
Failure of
Replacement
5
Dismantle the fuel injector and use the cleaning analyzer special for
fuel injector to check whether there is leakage, blockage or too poor
flow in the fuel injector.
No
Next step
Yes
Change fuel
6
Check fuel condition and observe whether the trouble phenomenon
occurs just after adding the fuel.
No
Next step
Yes
Eliminate the
mechanical trouble of
engine
7
Check pressure of all the cylinders and observe whether the
pressure difference of each engine cylinders is large.
No
Next step
Yes
Next step
8
Check whether the ignition sequence of engine and ignition timing
is in compliance with specification.
No
Repair ignition timing
Yes
Diagnosis help
9
Turn on the ignition switch and check whether the power supply
and earthing are normal.
No
Repair related circuit