Chery QQ6 (UMC EFI for 473F Engine). Service Instruction — part 5

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.

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

Yes

Replace ECU

12

Check if the spark plug is in right conditions.

No

Replace spark plug

Note: For periodic unsteadiness, mainly check air intake system for air leak or
electronic throttle body for failure. Following are the steps for inspection of electronic
throttle body: while turning on ignition key, throttle may jiggle; during self-checking
procedure, throttle should act with actions of accelerator pedal.

12.12 Too High Idle Speed (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

Adjust or replace

2

Check if throttle valve plate is locked and if

failure exists in electronic throttle body.

No

Next step

Yes

Repair or replace

3

Check if the canister control valve, the fuel

pressure

regulator,

the

positive

crankcase

ventilation vacuum pipe and the vacuum pipe of

brake system are mounted steadily or they are

damaged.

No

Next step

Yes

Next step

4

Run the engine at idle speed and use neutral. Step

on the accelerator and observe if the idle speed is

too high.

No

6

Yes

Repair or replace

the vacuum booster

5

Clamp the vacuum pipe and observe if the idle

speed becomes normal.

No

Next step

Yes

Replace PVC valve

6

Replace PVC valve and clamp the positive

crankcase ventilation vacuum pipe. Observe if the

idle speed becomes normal.

No

Next step

Yes

Replace the canister

control valve

7

Clamp the canister control valve pipe and observe

if the idle speed becomes normal.

No

Next step

Yes

Repair or replace

8

Check if electronic throttle body is dumb or

locked.

No

Next step

Yes

Repair or replace

9

Check other parts of air intake pipe for leakage.

No

Next step

Yes

Next step

10

Check if the gasket of fuel injector is in good

condition.

No

Replace the gasket

Yes

Replace ECU

11

Check air intake system for air leak and air flow

meter for normal working.

No

Replace the sensor

Note: Check if the system goes through self-study, if not, the system will be under
failure mode or an uncertain state all the time, which may result in too high idle speed
of engine. The other cause is air leak in the system, if air leakage in the system is too
large and exceeds regulation and control range of ECU, idle speed fluctuation may
occur.

12.13. Engine Revolution Speed is too Low or Flameout

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

Run the engine at idle speed and check if the

engine revolution speed is normal at idle speed.

No

Next

step,

overhaul

with

reference to idle

speed

failure

entries

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

Overhaul

Yes

Next step

5

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

systems

Yes

Next step

6

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

10

Yes

9

7

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

Next step

8

Clean out the fuel injector and look if it can

work correctly.

No

Replace

fuel

injector

Yes

Replace fuel

9

Check if fuel is bad or moisture.

No

15

Yes

Next step

10

Check if the fuel pressure value is below 350

kPa.

No

14

Yes

Next step

11

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

13

12

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

Yes

Replace

fuel

pressure regulator

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

13

Check if there is leaking or jam in oil intake

pipe.

No

Replace oil pump

Yes

Repair or replace

oil return pipe

14

Check if the oil return pipe is bended or

jammed.

No

Replace

fuel

pressure regulator

Yes

Next step

15

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.

No

Repair or replace

cable

Yes

Replace ECU

16

Check if ignition coil, ignition cable and spark

plug are normal.

No

Adjust or replace

the parts involved

Note: This phenomenon indicates a comparatively obvious failure and some minute
details, such as if strainer of the system or exhaust pipe is blocked and so forth, should
also be checked. For other causes, check spark plug and ignition cable etc.

12.14 Slow Response when Accelerating

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 off the engine. Check the air cleaner and

look if it is open.

No

Replace

Yes

Next step

3

Run the engine at idle speed and check if the

engine revolution speed is normal at idle speed.

No

Repair in accordance

with

idle

speed

failure item

Yes

Next step

4

Run the engine at idle speed and check if the air

intake pressure is from 35 to 65 kPa.

No

Overhaul

Yes

Next step

5

Put the ignition switch to “ON”. Check if it is

break or short circuit between 38#, 32#, 54#,

36# pins on ECU connector and 1#, 2#, 4#, 6#

pins of throttle position sensor of electronic

throttle valve body.

No

Repair or replace

Harness

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 is normal.

No

Check other part

Yes

Next step

7

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 4000kPa.

No

11

Yes

10

8

Use a special joint to directly provide 12V

power supply and intermittent 12V power

supply from battery to injector and check if the

injector can work intermittently.

No

Next step

Yes

Next step

9

Clean out the fuel injector and look if it can

work correctly.

No

Replace fuel injector

Yes

Replace fuel

10

Check if fuel is bad or moisture.

No

16

Yes

Next step

11

Check if the fuel pressure value is below 300

kPa.

No

15

Yes

Next step

12

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

14

Yes

Replace the pressure

regulator

13

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

14

Check if there is leaking or jam in oil intake

pipe.

No

Replace oil pump

Yes

Repair or replace oil

return pipe

15

Check if the oil return pipe is bended or

jammed.

No

Replace the pressure

regulator

Yes

Replace or clean

16

Check if the exhaust system and three-way

catalytic converter are jammed.

No

Replace ECU

Note: For slow response when accelerating, mainly check air intake pressure and injection pulse-width

etc.; choked exhaust pipe and smudgy air cleaner may be causes for this problem. In addition, spark plug

and ignition cable problems may also be causes.

12.15 Poor Performance and Disability when Accelerating.

Yes

Repair

1

Check if failure occurs, such as clutch slipping,

low tire pressure, brake delay, wrong tire size

and incorrect four-wheel alignment.

No

Next step

Yes

Next step

2

Check if the electronic throttle can be full

opening.

No

Repair or replace the

throttle

Yes

Remove the failure

displayed

3

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

4

Let engine run at idle speed, after coolant

temperature reaches normal value, then use a

diagnostic tester to check the ignition advance

angle.

No

Check

the

parts

involved

Yes

Next step

5

Put the ignition switch to “ON”. Check if it is

break or short circuit between 38#, 32#, 54#,

36# pins on ECU connector and 1#, 2#, 4#, 6#

pins of throttle position sensor of electronic

throttle valve body. 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

Harness

Yes

Next step

6

Run the engine at idle speed and check if the air

intake pressure is from 35 to 65kPa.

No

Overhaul

Yes

Next step

7

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

11

Yes

10

8

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

Next step

9

Clean out the fuel injector and look if it can

work correctly.

No

Replace fuel injector

Yes

Replace fuel

10

Check if fuel is deteroprated or moisture.

No

16

Yes

Next step

11

Check if the fuel pressure value is below 300

kPa.

No

15

Yes

Next step

12

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

14

Yes

Replace the pressure

regulator

13

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

14

Check if there is leaking or jam in oil intake

pipe.

No

Replace oil pump

Yes

Repair or replace oil

return pipe

15

Check if the oil return pipe is bended or

jammed.

No

Replace the pressure

regulator

Yes

Next step

16

Check if leak and blocking exist in air intake

system and if air flow meter works normally.

No

Replace the sensor

Yes

Next step

17

Check if spark plug, ignition cable and ignition

coil are normal.

No

Replace or adjust

Yes

Check A/C system

18

Check if it results from air conditioning system.

No

Replace ECU

Note: Poor acceleration of system relates to many factors, such as problem in mechanical part of the

engine itself, cylinder pressure and carbon deposit on valve etc. In addition, it is also in connection with

other systems, such as power steering system and A/C system.

12.16 Unable to Reach the Maximum Revolution when Accelerating

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

With engine off, check if air cleaner is smooth

(can not simply rely on visualization, remove

the air cleaner and then perform test drive again)

and if air intake system is chocked.

No

Replace

Yes

Next step

3

Run the engine at idle speed and check if the

engine revolution speed is normal at idle speed.

No

Repair in accordance

with

idle

speed

failure item

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

Overhaul

Yes

Next step

5

Put the ignition switch to “ON”. Check if it is

break or short circuit between 38#, 32#, 54#,

36# pins on ECU connector and 1#, 2#, 4#, 6#

pins of throttle position sensor of electronic

throttle valve body.

No

Repair or replace

Harness

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 is normal.

No

Check other part

Yes

Next step

7

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

11

Yes

Next step

8

Check if working positions of camshaft position

sensor and crankshaft position sensor are

normal.

No

Replace

the

parts

involved

Yes

Next step

9

Clean out the fuel injector and look if it can

work correctly.

No

Replace fuel injector

Yes

Replace fuel

10

Check if fuel is deteroprated or moisture.

No

16

Yes

Next step

11

Check if the fuel pressure value is below 300

kPa.

No

15

12

Check if the exhaust system and three-way Yes

Replace or clean

catalytic converter are jammed.

No

Replace ECU

Note: In case the engine is unable to reach its maximum revolution when accelerating, mainly check if

exhaust pipe is chocked and air cleaner is smudgy. In addition, for electric control system of A21, in case

of a failure in crankshaft or camshaft position sensor, ECU will take restrictive driving measures to

restrict engine revolution to exceed certain value, which should be noted during maintenance process.