Chery QQ6 (S21) / S12LHD. Manual — part 114

12.9. Unsteady Idle Speed after Warming up

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

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

Repair or replace the

harness

Yes

Next step

3

Turn off the engine. Check the air cleaner and

look if it is open.

No

Replace

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

Eliminate the leakage

failure of air intake

system

Yes

Next step

5

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

9

Yes

8

6

Use a special joint to directly provide a 12V

power supply and intermittent ground wire from

battery to injector and check if the injector can

work intermittently.

No

Next step

Yes

Replace

7

Clean out the fuel injector and look if it can

work correctly.

No

Replace fuel injector

Yes

Replace fuel

8

Check if fuel is deteroprated or moisture.

No

14

Yes

Next step

9

Check if the fuel pressure value is below

300kPa.

No

13

Yes

Next step

10

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

12

Yes

Replace fuel pressure

regulator

11

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

12

Check if there is leaking or jam in oil intake

pipe.

No

Replace oil pump

Yes

Repair or replace oil

return pipe

13

Check if the oil return pipe is bended or

jammed.

No

Replace fuel pressure

regulator

Yes

Next step

14

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 systems

Yes

Replace the coolant

temperature sensor

15

Pull off the coolant temperature sensor and

observe if the engine is in right conditions.

No

Next step

Yes

Next step

16

Check if the compression pressure of cylinder is

normal.

No

Troubleshooting

Yes

Next step

17

Check if resistance value of ignition cable of

each cylinder is normal (can not exceed 16kÙ).

No

Replace

Yes

Replace

18

Check if ignition coil and ignition cable system

works normally and if crack exists on ignition

coil.

No

Next step

Yes

Replace ECU

19

Check if the spark plug is in right conditions.

No

Replace spark plug

Note: After finish of warming up, engine will enter normal idle speed state, under
which, unsteady revolution is in connection to many factors, such as spark plug, ignition
cable, ignition coil, if air leak exists in the system, if carbon deposit exists in the system
and if cylinder pressure is normal an so forth.

12.10 Unsteady Idle Speed or Extinguish with Load (A/C etc.)

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

Turn on A/C switch, connect an adaptor

between ECU and harness, and then measure

75# pin of ECU to see if input signal is present

(high potential signal loaded by A/C switch

through high and low voltage switches).

No

Check and repair air

conditioning circuit

Yes

Next step

3

Check if the pressure of air conditioning system,

the electromagnetic clutch of compressor and

the air conditioning pump are in right

conditions.

No

Repair or replace

Yes

Next step

4

Check the voltage on 64#, 65#, 66# and 67#

pins of ECU (for control of DC motor) as well

as corresponding pins on valve body is normal.

No

Check

controlling

circuit

Yes

Check the electric

throttle body

5

Remove electronic throttle body and check if

throttle is locked or is dumb to run.

No

Next step

Yes

Replace ECU

6

Start engine, turn on A/C, use a failure diagnosis

tester to read such signals as air intake flow and

engine revolution and check if engine

acceleration occurs.

No

Replace

the

electronic

throttle

body

Note: 75# pin is the up level request signal. When turning on A/C switch, an up level
signal will be sent to ECU through this pin, and then ECU will further check other
systems of A/C. If all systems are normal, ECU will control A/C relay to ground and
A/C system will start to work. 60# pin of ECU is medium voltage signal input; when
high potential signal is loaded on this pin, cooling fan will start and run at high speed.

12.11 Periodic Unsteadiness (Have to Perform Self-study again after ECU

is Power off)

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

Check and repair

air intake and leak

Yes

7

4

Let engine run at idle speed, spark out cylinder in

turn, and observe if engine revolution will fall and

fluctuate (it is prohibited to carry out spark out

experiment by disconnecting ignition cable).

No

Next step

Yes

Next step

5

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

Repair or replace

cable

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

of the system is normal.

No

Check other part

Yes

Sweep

7

Check air intake system for such failures that may

affect working of engine as blocking and air leak

etc.

No

Next step

Yes

Replace fuel

8

Check if fuel is deteroprated or moisture.

No

Next step

Yes

Next step

9

Use a special joint to directly provide a 12V

power supply and intermittent ground wire from

battery to injector and check if the injector can

work intermittently.

No

Check and repair

oil

injector

and

related wires

Yes

Next step

10

Check if the resistance values of cylinders’

ignition cable are normal.

No

Replace

Yes

Replace

11

Check if the ignition coil is damaged or cracked.

No

Next step