Chery QQ6 (S21) / S12LHD. Manual — part 211
12. Steps for Implementation of Failure Diagnosis by Engine
Symptom
12.1 Perform Preliminary Inspection First before Following the Steps for
Implementation of Failure Diagnosis by Engine Symptom.
(1) Make sure that ECU and failure indicator lamp (or EPC lamp) have no off-normal
phenomenon (excluding the models that have no failure indicator lamp).
(2) Use a failure diagnostic tester to check and make sure no failure information record
exists.
(3) Employ failure diagnostic tester to check that hot idle data from electronic control
system fall within normal scope.
Hot idle speed parameter table:
Name
Parameter
Air intake temperature
20-70℃
Battery voltage
12-14V (affected by engine revolution)
Temperature of engine coolant
80-90
(normal operating temperature)
℃
Position of accelerator pedal
0%~99.00%
Air-fuel ratio control integrator
5%-5%
Ignition advance angle
5-10
°
(
may change with fluctuation of
engine revolution)
Outer corner of throttle
0%~99.61%
Fuel injection time
2-7ms (has a strong relation with engine
revolution)
Engine revolution n
Expected idle speed ± 50rpm
Duty cycle of canister control valve
0%~99.9%
Self-adapting value of air-fuel ratio
control
0.95-1.05
Self-adapting value of air-fuel ratio
control
120-140
Intake manifold absolute pressure
350-650hPa
Voltage of oxygen sensor
Quickly fluctuates at 0.1-0.9V
Air intake pressure
(4) Validate that the failure effect the owner complained exists and then locate the exact
position of the symptom. Please note that the information provided by the customer is
very important, especially the failure symptoms, occurrence time, position and if any
other failure symptoms occurred before; these information can help technical personnel
rapidly and effectively judge the failure, thus increasing maintenance speed and
improving maintenance quality.
Then check the appearance:
Check that grounding of wire harness is clean and firm.
Check that vacuum pipeline is unbroken, twisted and in right connection.
Check that there is no obstruction in pipe.
Check that air intake pipe is not squashed or damaged.
Check that the seal between throttle body and intake manifold is perfect.
Check that ignition cable of ignition system is unbroken, no ageing and in right wiring.
Check that wires are in right connection, no loosing or poor connection for connectors.
12.2 The Engine Does not Rotate or Rotates Slowly when Starting
No.
Operating steps
Result
Follow up steps
Yes
Next step
1
Use a multimeter to check if a voltage around
10-12.5V is present between two battery
terminals.
No
Repair
or
replace
the
battery
Yes
Next step
2
Put the ignition switch to “ON”. Use a
multimeter to check if a battery voltage around
10-12.5V is present on the terminal on the
ignition switch that connects with anode of
battery.
No
Repair
wiring
terminal
or
replace cable
Yes
Next step
3
Maintain ignition switch at START position,
and then use a multimeter to check if a voltage
above 8V is present on the terminal on the
ignition switch that connects with pull in
winding of starting motor.
No
Replace
the
ignition switch
Yes
Next step
4
Put the ignition switch at start position, check
the anode terminal of starting motor by
multimeter and observe the voltage if it is above
8V.
No
Repair
wiring
terminal
Or
replace
cable
Yes
Repair
or
replace
the
starting motor
5
Check if it is short circuit or break circuit in the
starting motor.
No
Next step
Yes
Troubleshootin
g
6
Check if there is jammed by poor lubricating.
No
Next step
Yes
Replace
with
appropriate oil
7
If the failure is happened in winter time, check if
it is because of the wrong engine lubricant and
gearbox oil causes the big resistance of the
starting motor.
No
Check if other
systems
are
normal
Note: When this problem occurs, mainly inspect voltage, starter and ground system. In
modern sedan, lubricant has little effect on startup of the vehicle, so, basically, it needs
not to allow for lubricant problem, but the problem if the engine has too large self
resistance should be taken into consideration.
12.3 When Starting, Engine Can be Dragged to Rotate but Can not Start
with Success.
No.
Operating steps
Result
Follow up steps
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
8
2
Pull out cylinder distribution wire, connect
spark plug with the distance between electrode
of spark plug and engine body as 8-10mm, use
the starting motor to drag the engine to rotate,
and then check if blue-white high-voltage spark
occurs (disconnect all injection nozzles on the
engine).
No
Next step
Yes
Next step
3
Check if resistance value of ignition cable is
normal (can not exceed 16kΩ).
No
Repair, replace the
ignition cable.
Yes
Replace
4
Check ignition coil and ignition cable for burn
through, damage and crack.
No
Next step
Yes
Replace
5
Check if ignition cable is normal.
No
Next step
Yes
Next step
6
Check if the ignition coil is working normally.
No
Replace
Yes
Next step
7
Check if connectors of ignition coil and
ignition cable are connected properly.
No
Connect
the
connectors
properly
Yes
Next step
8
Put the ignition switch to “ON”. Check if fuel
pump relay and fuel pump can keep working for
a period of time.
No
Overhaul the fuel
pump circuit
Yes
Next step
9
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
13
Yes
12
10
Pull off the fuel distributing pipe and the fuel
injector; pull off the joints of fuel injector on the
harness one by one. And supply the voltage of
12 V from battery to fuel injector directly and
look if the fuel injector can inject normally.
No
Next step
11
Yes
Next step
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