Engine Electrical System

9) Unstable idle speed after engine warm-up
Yes
Fix the indicated
malfunction.
1
Turn the ignition switch to “ON” position.
Inspect with the diagnostic tester to see
whether there is any malfunction
information record.
No Proceed to next step.
Yes Proceed to next step.
2
Turn the ignition switch to “ON” position
and connect the adaptor between ECU and
the wiring harness. Verify that the
voltages at following ECU’s pins such as
absolute pressure sensor output of air
intake manifold, air intake temperature
sensor output, coolant temperature sensor
output, oxygen sensor output and ECU’s
output voltage connected to idle actuator’s
pin are normal.
No
Repair or replace the
wiring harness and
relevant parts.
Yes Proceed to next step.
3
Shut down the engine and verify that the
air filter is free of any blockage.
No Replace
Yes Proceed to next step.
4
Verify that the air intake manifold
pressure is maintained between 35-65 kPa
at idle speed.
No
Fix the leakage of air
intake system
Yes Proceed to next step.
5
Connect the fuel manometer valve (the
connecting points will depend on the types
of car models). Short the 30# and 87# pins
of the fuel pump relay to operate the fuel
pump in order to verify that the fuel
pressure is maintained at about 350kPa.
No Proceed to Step 9
Yes Proceed to Step 8
6
Provide a voltage supply of 12V with
special connector between the battery and
the fuel injector, and verify that the fuel
injector is functioning normally.
No Proceed to next step.
Yes Replace
7
After washing and cleaning the fuel
injector, inspect again to see whether it
can function normally.
No
Replace the fuel
injector.
Yes Replace the fuel.
8
Verify that the fuel is deteriorated or
contaminated with water.
No Proceed to Step 14.
Yes Proceed to next step.
9
Verify that the fuel pressure is lower than
350kPa.
No Proceed to Step 13.
Yes Proceed to next step.
10
Turn off the fuel manometer valve.
Connect the ignition switch again to
re-operate the fuel pump in order to verify
that the fuel pressure can be established.
No Proceed to Step 12.
11
Turn on the fuel manometer valve and
clamp the fuel return pipe with the fuel
Yes
Replace the fuel
pressure regulator.
E-76
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