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

Use a multimeter to check if a voltage around

10-12.5V is present between two battery

terminals.

Repair

replace

the

battery

Yes

Next step

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.

Repair

wiring

terminal

replace cable

Yes

Next step

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.

Replace

the

ignition switch

Yes

Next step

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.

Repair

wiring

terminal

replace

cable

Yes

Repair

replace

the

starting motor

Check if it is short circuit or break circuit in the

starting motor.

Next step

Yes

Troubleshootin

Check if there is jammed by poor lubricating.

Next step

Yes

Replace

with

appropriate oil

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.

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

Put the ignition switch to “ON”. Use a failure

diagnostic tester to check if any failure

information record exists.

Next step

Yes

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).

Next step

Yes

Next step

Check if resistance value of ignition cable is

normal (can not exceed 16kΩ).

Repair, replace the

ignition cable.

Yes

Replace

Check ignition coil and ignition cable for burn

through, damage and crack.

Next step

Yes

Replace

Check if ignition cable is normal.

Next step

Yes

Next step

Check if the ignition coil is working normally.

Replace

Yes

Next step

Check if connectors of ignition coil and

ignition cable are connected properly.

Connect

the

connectors

properly

Yes

Next step

Put the ignition switch to “ON”. Check if fuel

pump relay and fuel pump can keep working for

a period of time.

Overhaul the fuel

pump circuit

Yes

Next step

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.

Yes

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.

Next step

Yes

Next step

Content .. 209 210 211 212 ..