Chery QQ6 (S21) / S12LHD. Manual — part 113

No

17

Yes

Next step

12

Check if the fuel pressure value is below 300 kPa.

No

16

Yes

Next step

13

Close the fuel manometer valve. Re-engage the

ignition switch to let the fuel pump run for a

period of time, and then check if fuel pressure can

be built up.

No

15

Yes

Check fuel pressure

regulator and fuel

pump

14

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

not return. Check if the oil pressure occurs

immediately.

No

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil intake pipe

15

Check if the oil intake pipe is leaky or jammed.

No

Replace oil pump

Yes

Repair or replace

oil return pipe

16

Check if the oil return pipe is bended or jammed.

No

Replace

fuel

pressure regulator

or fuel pump

Yes

Next step

17

Check if the pressure of cylinder is normal.

No

Troubleshooting

Yes

Repair

18

Check if the engine air intake system is leaky.

No

Next step

Yes

Repair or replace

19

If air cleaner or airflow sensor is choked.

No

Replace ECU

Note: The cold starting problem relates to more failure points, among which water
temperature sensor is comparatively important, because it is the major parameter for
determination of injection pulse-width when starting the engine. In case of a water
temperature sensor failure or it generates a false signal, the system can not judge the
temperature and starting difficulty may occur.

12.7 Unsteady Idle Speed at Any Time

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

Repair or replace

the

electronic

throttle

2

Check if electronic throttle system of engine

works normally.

No

Next step

Yes

Check wires and

plugs

3

Turn on ignition switch, connect an adaptor

between ECU and harness, and then check if the

voltage between 17# and 42# pins of ECU,

between 39# and 17# pins of ECU (signal output

terminal of intake air temperature sensor and

coolant temperature sensor) as well as 64#, 65#,

66#, 67# pins of ECU (for control of DC motor) is

normal.

No

Next step

Yes

8

4

Let engine run at idle speed, spark out cylinder in

turn, and observe if engine revolution will fall and

fluctuate (cut fuel to injector).

No

Next step

Yes

Next step

5

Check the fuel injectors of each cylinder and look

if they are in right conditions.

No

Check fuel injector

and wires

Yes

Next step

6

Check if resistance value of ignition cable of each

cylinder is normal (can not exceed 16kΩ).

No

Replace

Yes

Maintain

7

Check if ignition system works normally.

No

Next step

Yes

Next step

8

Check if the spark plug is in right conditions.

No

Replace spark plug

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

Use a special joint to directly provide a 12V

power supply and intermittent ground wire signal

from battery to injector and check if the injector

can work intermittently.

No

Next step

Yes

Next step

11

Clean out the fuel injector and look if it can work

correctly.

No

Replace

fuel

injector

Yes

Replace fuel

12

Check if fuel is deteroprated or moisture.

No

18

Yes

Next step

13

Check if the fuel pressure value is below 300kPa.

No

17

Yes

Next step

14

Close the fuel manometer valve. Re-engage the

ignition switch to let the fuel pump run for a

period of time, and then check if fuel pressure can

be built up.

No

16

Yes

Replace

fuel

pressure regulator

15

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

not return. Check if the oil pressure occurs

immediately.

No

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil return pipe

16

Check if there is leaking or jam in oil intake pipe.

No

Replace oil pump

Yes

Repair or replace

oil return pipe

17

Check if the oil return pipe is bended or jammed.

No

Replace

fuel

pressure regulator

Yes

Use detergent to

wash

18

Check the pressure of air intake pipe and if the

sense port of air intake temperature sensor is

jammed.

No

Next step

Yes

Next step

19

Let engine run at idle speed, after coolant

temperature reaches the active temperature of

closed loop control, observe if the oxygen sensor

works normally (rapidly fluctuate between 0.1V

and 0.9V).

No

Check the oxygen

sensor and harness

Yes

Remove leakage

20

Check if the engine air intake system is leaky.

No

Next step

Yes

Next step

21

Check if the pressure of cylinder is normal.

No

Troubleshooting

Yes

Replace ECU

22

Let engine run at idle speed, after coolant

temperature reaches normal value, then use a

special diagnostic tester to check if ignition

advance angle is within the standard scope.

No

Check other part

Note: Unsteady idle speed relates to many systems, such as air leak, carbon deposit and
throttle body etc.; before replacing a part, make sure that air cleaner, spark plug and
ignition system of engine are normal.

12.8 Unsteady Idle Speed during Warming up Process

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

Check the air cleaner and look if it is open.

No

Replace

Yes

Next step

3

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

Eliminate

the

leakage failure of

air intake system

Yes

Next step

4

Turn on ignition switch, connect an adaptor

between ECU and harness, and then check if the

voltage between 17# and 42# pins of ECU,

between 39# and 17# pins of ECU (signal output

terminal of intake air temperature sensor and

coolant temperature sensor) as well as 64#, 65#,

66#, 67# pins of ECU (for control of DC motor) is

normal.

No

Overhaul

Yes

Next step

5

Before finish of warming up of engine, pull out

the joint on electronic throttle body and observe if

engine revolution will change.

No

Check the electric

throttle body

Yes

Next step

6

Check if the coolant temperature sensor is

working correctly.

No

Replace

Yes

Replace ECU

7

Let engine run at idle speed, after coolant

temperature reaches normal value, then use a

special short diagnostic tester to check if ignition

advance angle is normal.

No

Check the ignition

timing mechanism

Note: Unsteady idle speed occurs seldom during warming up process, its
troubleshooting is similar to that for previous case, but validate if water temperature
sensor works normally in advance.