Chery QQ6 (UMC EFI for 473F Engine). Service Manual — part 6

12.17 When Releasing Accelerator Pedal after Acceleration, Unsteady Idle

Speed Occurs at Instant, even Extinguishes.

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

Clear carbon deposit

8

Remove air intake hose, check if carbon deposit

or other soil (this may result in air intake system

of engine being chocked when the valve plate

closes) exists.

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

11

Check if the fuel pressure value is below 400 Yes

Next step

kPa.

No

15

Yes

Replace or clean

12

Check if the exhaust system and three-way

catalytic converter are jammed.

No

Replace ECU

Note: For an electric control motor with the electronic throttle body, the main actuators of its air intake

system are air flow meter and electronic throttle body. Air flow meter has very high operational reliability

and very low failure rate, while, due to particularity of road status in China and affected by operating

environment, choke is liable to occur between valve plate and valve body of the electronic throttle body,

which may obstruct air from entering the engine and result in extinguish of engine.

12.18 A/C System Failure

Yes

Next step

1

Check if there is enough coolant, if the A/C belt,

the A/C clutch and the pressure switch are in

good condition.

No

Troubleshooting

Yes

Remove the failure

displayed

2

Let engine run at idle speed and turn on A/C

switch. Enter A/C self diagnosis mode to check

the A/C system for failure.

No

Next step

Yes

Next step

3

Turn on the A/C switch and connect an adaptor

between ECU and harness. Measure 75# pin

(A/C switch) of ECU and see if there are input

signals on it.

No

Check the harness

Yes

Replace or repair the

harness

4

If this vehicle adopts low level control, check if

the air condition is working still even though it

is turned off.

No

Next step

Yes

Repair

the

A/C

replay and harness

5

Check if there is low level output at ECU pin

No.69 (connect to the ground of pull in winding

of A/C relay).

No

Replace ECU

Note: Different from the controlling means of other models, the A/C control system of A21 adopts the

automatic A/C and uses double-pressure switch to control incorporation of the A/C system and the fan

after A/C starts up.

13. Safety Precautions for System Maintenance

13.1 Safety Precautions for Diagnosis and Maintenance of Gasoline

Injection Electronic Control System

(1) Disassembly and assembly requirements for electronic control unit (ECU):

Controllers shall be removed before welding or paint-baking;
When disassembling and installing the controller, be sure to set ignition switch to
CLOSE position and disconnect the battery with the system for fear to damage the
engine control unit during disassembly and installation.
Power supply wires shall not be removed from battery when engine is in operation or
electric system is in use;
Do not use such heavy current equipment as charger etc. to start the engine by direct
bridging;
Note that the ambient temperature for the controller should not exceed 80 .

℃

(2) Requirements for cleanness: the following rules should be observed for any
operation on oil-supply system and oil-injection system:
The parts removed should be place at a clean site and covered properly; do not use the
cloth (cotton cloth and gauze) with falling off fibre;

(3) Connect and disconnect the connectors of all sorts of harnesses and the connectors
of failure diagnosis testers only after the ignition switch is turned off.
When measuring mains voltage or ground wire grounding of the electronic control
system, be sure to check if the connection order and mode are correct;
Disconnect power cord or ground wire of battery from the system and disconnect
harness connector of ECU; both operation modes above may cause loss of information
about diagnosis and self-study stored in ECU (the retention time of information after the
ECU installed is power off depends on the model).

(4) Attentions during maintenance of fuel feed system (fuel feed line, fuel pump
and fuel injection system):

Disassembly or installation of oil pump on the tank full of oil or partly full of oil,

please note:
Before operation, get material ready near the fuel tank opening for absorption of heavy
discharging fuel, so that, the fuel discharged can be duly absorbed;
Avoid skin from direct contact with gasoline as best as you can;
Before loosening a connection part, thoroughly clean this part and the area around the
connecting pieces;
Dishcloth shall be placed around the connecting part for avoide oil-spraying;

If disassembled parts can not be repaired or for other processing immediately, store
them properly.
The spare parts can be taken out of their package only when they are to be installed; do
not use the spare parts without package or with package heavily damaged;
When installing an injector, be careful not to damage the O-gaskets at both ends of the
injector; for installation convenience, apply a little lubricant on the O-gaskets.
After fuel and fuel feed systems are disassembled, avoid use of compressed air and
move of the vehicle as best as you can.

(5) Safety precaution
In order to avoid maintenance technical personnel from being injured and fuel injection
and ignition devices from being damaged, please note:

In case the engine is running or under starting speed, disconnection of ignition

harness is forbidden. Checking the engine for poor working of single cylinder by means
of spark test with ignition cable disconnected is not allowed;

if it is required to drag the engine by the starter without starting the engine itself,

for example, in the case of inspection of cylinder pressure of engine etc., disconnect the
harness connectors on engine revolution sensor and camshaft (phase) sensor and
connect each sensor properly after the corresponding job has finished, and then use a
special diagnostic tester for Chery to clear the failure codes in the system;

When the engine is running at high speed, touching wheel train of engine and

revolving parts are forbidden;

When the engine reaches normal operating temperature, both water temperature

and pressure of cooling system are very high; therefore, in case maintenance for the
cooling system of engine is required, perform corresponding operations only after the
engine has stopped and the cooling system has been fully cooled.

When maintaining fuel system of engine, if maintenance for engine compartment

is involved, perform the operations only after temperature inside engine compartment of
the vehicle has adequately fell;

Under a state that power on of the system is normal, do not touch cooling fan of

the engine by hand at any time, because the cooling fan may start up abruptly.