12.17 When Releasing Accelerator Pedal after Acceleration, Unsteady Idle
Speed Occurs at Instant, even Extinguishes.
Yes Remove the failure
displayed
1 Put the ignition switch to “ON”. Use a failure
diagnostic tester to check if any failure
information record exists.
No Next step
Yes Next step 2 With engine off, check if air cleaner is smooth
(can not simply rely on visualization, remove
the air cleaner and then perform test drive again)
and if air intake system is chocked.
No Replace
Yes Next step 3 Run the engine at idle speed and check if the
engine revolution speed is normal at idle speed.
No Repair in accordance
with idle speed
failure item
Yes Next step 4 After starting successfully, check if air intake
consumption of the engine at idle speed is
around 300Kg/h (remember to check if cylinder
pressure is normal).
No Overhaul
Yes Next step 5 Put the ignition switch to “ON”. Check if it is
break or short circuit between 38#, 32#, 54#,
36# pins on ECU connector and 1#, 2#, 4#, 6#
pins of throttle position sensor of electronic
throttle valve body.
No Repair or replace
Harness
Yes Next step 6 Let engine run at idle speed, after coolant
temperature reaches normal value, then use a
diagnostic tester to check if ignition advance
angle is normal.
No Check other part
Yes Next step 7 Connect fuel manometer valve. Short 30# and
87# pins of fuel pump relay to make the fuel
pump run, and then check if fuel pressure is
around 400kPa.
No 11
Yes Clear carbon deposit 8 Remove air intake hose, check if carbon deposit
or other soil (this may result in air intake system
of engine being chocked when the valve plate
closes) exists.
No Next step
Yes Next step 9 Clean out the fuel injector and look if it can
work correctly.
No Replace fuel injector
Yes Replace fuel 10 Check if fuel is deteroprated or moisture.
No 16
11 Check if the fuel pressure value is below 400 Yes Next step
