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Chery QQ6 (S21) / S12LHD. Manual - part 258

12.6 Cold Starting Difficulty

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

Next step

Use a multimeter to check if the coolant

temperature sensor is normal. (A 2.8KΩ electric

resistance can also be connected in series between

39# and 17# pins of ECU to start the engine in

stead of the coolant temperature sensor. If the

engine can start, it indicates off normal of coolant

temperature sensor.)

Replace the sensor

Yes

Next step

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

on the following pins of ECU is normal: if it is a

battery voltage around 12V on 12#, 14#, 15# pins;

if the voltage between 51#, 53#, 3#, 61#, 80# pins

and the wire is zero.

Check wires and

plugs

Yes

Next step

Check the air cleaner and look if it is open.

Replace

Yes

Next step

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).

Eliminate

the

leakage failure of

air intake system

Yes

Check

the

electronic throttle

Step on the throttle slightly and observe if it is

easy to be started easily.

Next step

Yes

Next step

When engine coolant is at low temperature, pull

out electronic throttle body joint on harness and

observe if engine revolution will rise.

Check the electric

throttle body

Yes

Next step

Connect fuel manometer valve. Let 86# pin of fuel

pump relay directly ground. Turn on ignition

switch to make fuel pump relay and fuel pump

work, and then check if fuel pressure is at around

400kPa.

Yes

Use a special joint to directly provide a 12V

electricity and ground wire from battery to injector

and check if the injector works normally.

Next step

Yes

Next step

Clean out the fuel injector and look if it can work

correctly.

Replace

fuel

injector

Check if fuel is deteroprated or moisture.

Yes

Replace fuel

Yes

Next step

Check if the fuel pressure value is below 300 kPa.

Yes

Next step

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.

Yes

Check fuel pressure

regulator and fuel

pump

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.

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil intake pipe

Check if the oil intake pipe is leaky or jammed.

Replace oil pump

Yes

Repair or replace

oil return pipe

Check if the oil return pipe is bended or jammed.

Replace

fuel

pressure regulator

or fuel pump

Yes

Next step

Check if the pressure of cylinder is normal.

Troubleshooting

Yes

Repair

Check if the engine air intake system is leaky.

Next step

Yes

Repair or replace

If air cleaner or airflow sensor is choked.

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

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

diagnostic tester to check if any failure

information record exists.

Next step

Yes

Repair or replace

the

electronic

throttle

Check if electronic throttle system of engine

works normally.

Next step

Yes

Check wires and

plugs

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.

Next step

Yes

Let engine run at idle speed, spark out cylinder in

turn, and observe if engine revolution will fall and

fluctuate (cut fuel to injector).

Next step

Yes

Next step

Check the fuel injectors of each cylinder and look

if they are in right conditions.

Check fuel injector

and wires

Yes

Next step

Check if resistance value of ignition cable of each

cylinder is normal (can not exceed 16kΩ).

Replace

Yes

Maintain

Check if ignition system works normally.

Next step

Yes

Next step

Check if the spark plug is in right conditions.

Replace spark plug

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

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.

Next step

Yes

Next step

Clean out the fuel injector and look if it can work

correctly.

Replace

fuel

injector

Yes

Replace fuel

Check if fuel is deteroprated or moisture.

Yes

Next step

Check if the fuel pressure value is below 300kPa.

Yes

Next step

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.

Yes

Replace

fuel

pressure regulator

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.

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil return pipe

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

Replace oil pump

Yes

Repair or replace

oil return pipe

Check if the oil return pipe is bended or jammed.

Replace

fuel

pressure regulator

Yes

Use detergent to

wash

Check the pressure of air intake pipe and if the

sense port of air intake temperature sensor is

jammed.

Next step

Yes

Next step

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).

Check the oxygen

sensor and harness

Yes

Remove leakage

Check if the engine air intake system is leaky.

Next step

Yes

Next step

Check if the pressure of cylinder is normal.

Troubleshooting

Yes

Replace ECU

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.

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.

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