Chery QQ6 (UMC EFI for 473F Engine). Service Manual — part 1

Service Manual for Chery

QQ6

(UMC EFI for 473F Engine)

CONTENTS

CHAPTER ONE DISASSEMBLY AND INSTALLATION OF ELECTRONIC FUEL

INJECTION SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...4

I. Disassembly and Installation of Components of Electronic Fuel Injection System . . . . ..4

CHAPTER TWO PRINCIPLE OF ELECTRONIC FUEL INJECTION SYSTEM . . . . ...6

I. Overhaul of System Components . . . . . . . . . . . . . . . . . . . . . . . ..6

1. Intake Air Temperature Pressure Sensor . . . . . . . . . . . . . . . . . . ...6

2. Tachogenerator of Engine . . . . . . . . . . . . . . . . . . . . . . . . .8

3. Phase Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...10

4. Water Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . ..10

5. Knock Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..12

6. Electric Throttle Body. . . . . . . . . . . . . . . . . . . . . . . . . .12

7. Oxygen Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8. Fuel Pump Assembly . . . . . . . . . . . . . . . . . . . . . . . . . ..16

9. Injector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

10. Ignition Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..19

11. Spark Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

12. Carbon Canister Solenoid Valve Control . . . . . . . . . . . . . . . . . ..22

13. Electronic Accelerator Pedal. . . . . . . . . . . . . . . . . . . . . . .24

14. Three-way Catalytic Converter . . . . . . . . . . . . . . . . . . . . . .24

15. Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...25

16. Position Sensor of Double Brake Pedal . . . . . . . . . . . . . . . . . . 26

17. Clutch Position Sensor . . . . . . . . . . . . . . . . . . . . . . . . ..26

18. A/C Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . ...27

CHAPTER TWO FUNDAMENTAL PRINCIPLE FOR FAILURE DIAGNOSIS OF

ELECTRONIC FUEL INJECTION SYSTEM . . . . . . . . . . . . . . . . . . . .28

1. Failure Information Records . . . . . . . . . . . . . . . . . . . . . . . . ...28

2. Failure State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3. Failure Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..28

4. Failure Frequency Counter . . . . . . . . . . . . . . . . . . . . . . . . . .28

5. Limp Home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

6. Failure Alert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

7. Readout of Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..29

8. Clearing Failure Information Records . . . . . . . . . . . . . . . . . . . . . 30

9. Failure Locating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..30

10. Failure Code Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

11. The Steps for Implementation of Failure Diagnosis According to Failure Information

Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...35

11.1 Electronic Throttle Failure . . . . . . . . . . . . . . . . . . . . . . ..35

11.2 Knock Sensor failure. . . . . . . . . . . . . . . . . . . . . . . . ...36

11.3 Air Pressure Sensor Failure . . . . . . . . . . . . . . . . . . . . . . 37

11.4 Front Oxygen Sensor Failure . . . . . . . . . . . . . . . . . . . . . ..38

11.5 Rear Oxygen Sensor Failure . . . . . . . . . . . . . . . . . . . . . ...40

11.6. Coolant Temperature Sensor Failure . . . . . . . . . . . . . . . . . . .42

11.7 Failure in Driver Stage of Injector . . . . . . . . . . . . . . . . . . . ..43

11.8 Failure in Driver Stage of Canister Control Valve. . . . . . . . . . . . . ..44

11.9 Failure in Driver Stage of Malfunction Indicator Lamp (MIL) . . . . . . . . ..45

11.10 Failure in Driver Stage of 1#, 2# Coils of Step Motor . . . . . . . . . . . ..46

11.11 Craftshaft Position Sensor Failure . . . . . . . . . . . . . . . . . . . 47

11.12 Craftshaft Position Sensor Failure . . . . . . . . . . . . . . . . . . . 48

11.12 Ignition Coil Failure. . . . . . . . . . . . . . . . . . . . . . . . ..49

11.13 Accelerator Pedal Position Sensor Failure. . . . . . . . . . . . . . . . 50

11.14 Double Brake Swtich . . . . . . . . . . . . . . . . . . . . . . . . 51

11.15 Theft-proof Control System Failure. . . . . . . . . . . . . . . . . . ..52

12. Steps for Implementation of Failure Diagnosis by Engine Symptom. . . . . . . . ...53

12.1 Perform Preliminary Inspection First before Following the Steps for Implementation

of Failure Diagnosis by Engine Symptom. . . . . . . . . . . . . . . . . . . .53

12.2 The Engine Does not Rotate or Rotates Slowly when Starting. . . . . . . . ...55

12.3 When Starting, Engine Can be Dragged to Rotate but Can not Start with Success. ...56

12.4 Warm Starting Difficulty . . . . . . . . . . . . . . . . . . . . . . . 58

12.5 Engine Speed is Normal, but it is Difficult to Start at any Time. . . . . . . . ...60

12.6 Cold Starting Difficulty . . . . . . . . . . . . . . . . . . . . . . . ..62

12.7 Unsteady Idle Speed at Any Time . . . . . . . . . . . . . . . . . . . ..64

12.8 Unsteady Idle Speed during Warming up Process . . . . . . . . . . . . . ..66

12.9. Unsteady Idle Speed after Warming up . . . . . . . . . . . . . . . . . .67

12.10 Unsteady Idle Speed or Extinguish with Load (A/C etc.). . . . . . . . . . .69

12.11 Periodic Unsteadiness (Have to Perform Self-study again after ECU is Power off) 70

12.12 Too High Idle Speed (Have to Perform Self-study again after ECU is Power off) ..72

12.13. Engine Revolution Speed is too Low or Flameout . . . . . . . . . . . . ..73

12.14 Slow Response when Accelerating . . . . . . . . . . . . . . . . . . ...75

12.15 Poor Performance and Disability when Accelerating. . . . . . . . . . . . ..77

12.16 Unable to Reach the Maximum Revolution when Accelerating. . . . . . . ...79

12.17 When Releasing Accelerator Pedal after Acceleration, Unsteady Idle Speed Occurs

at Instant, even Extinguishes. . . . . . . . . . . . . . . . . . . . . . . ...81

12.18 A/C System Failure. . . . . . . . . . . . . . . . . . . . . . . . ...83

13. Safety Precautions for System Maintenance. . . . . . . . . . . . . . . . . . .84

13.1 Safety Precautions for Diagnosis and Maintenance of Gasoline Injection Electronic

Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...84

Chapter One Disassembly and Installation of Electronic Fuel

Injection System

I. Disassembly and Installation of Components of Electronic Fuel

Injection System

1. Disassembly and installation of engine control unit (ECU).

2. Position and disassembly of intake air pressure sensor.

3. Position and disassembly of camshaft position sensor.

4. Remove fixing hoop of intake hose.

5. Remove the four fixing bolts of electronic throttle body.

Pull out the connector and take out the electronic throttle body.

6. Use a screwdriver to press down the fixed clip of the injection

nozzle connector and then pull out the connector.

7. Use a screwdriver to press down the fixed clip of the knock

sensor connector and then pull out the connector.

8. The water temperature sensor is behind the thermostat seat.

9. Pull out the connector of the ignition primary coil by hand.

10. Pull out the connector of the engine tachogenerator by hand.

Chapter Two Principle of Electronic Fuel Injection System

I. Overhaul of System Components

1. Intake Air Temperature Pressure Sensor

1.1 Function of the sensor:

Detect air intake pressure and temperature in air intake manifold, which will be provided to

ECU as main load signal of engine; ECU will calculate injection pulse-width based on this signal.

1.2 Principle of the sensor:

Intake air temperature pressure sensor is a sensor that integrates an intake air pressure sensor

and an intake air temperature sensor. Absolute pressure sensor element of intake manifold is

composed of a silicon chip. A pressure diaphragm is etched on the silicon chip. On the pressure

diaphragm, there are 4 piezo-resistances, which serve as strain sensors and constitute a Wheatstone

bridge. In addition to this pressure diaphragm, a signal processing circuit is also integrated on the

silicon chip. The silicon chip and a metal housing constitute a closed reference, where the absolute

pressure of the gas inside approaches to zero. Thus, a micro-electronic mechanical system is

formed. The active face of the silicon chip stands a pressure close to zero, while its back face stands

the pending measuring intake manifold absolute pressure introduced by a connecting pipe. The

thickness of the silicon chip is merely several

µ

m, so the absolute pressure change in intake manifold

will bring mechanical deformation to the silicon chip. The 4 piezo-resistances will accordingly

deform and their resistances also change. The voltage signal in linear relation to the pressure is

formed after process by the signal processing circuit on the silicon chip. The intake temperature

sensor element is a negative temperature coefficient (NTC) resistance, which will change with the

intake temperature. This sensor sends out a voltage indicating the intake temperature change to the

controller.

Cross-section view for sensor of air absolute pressure and temperature in intake manifold

1 Gasket 2 Stainless Steel Sleeve 3 PCB Board 4 Sensing Element 5 Housing 6 Pressure Bracket 7 Soldering 8

Bonded With Bonding Agent

进气压力温度传感
器

Intake air temperature

pressure sensor

1.3 Parameters of technical features

This sensor is designed to be mounted on the plane of auto engine intake manifold. The

pressure connecting pipe together with the temperature sensor protrudes inside the intake manifold

and an O gasket is used to enable atmosphere-proof.

If it is mounted on an auto through an appropriate method (picks up pressure from the intake

manifold and the pressure connecting pipe tilts down etc.), it can be ensured that no condensed water

will be formed on the pressure-sensitive element.

Drilling and fixing on the intake manifold must be carried out according to the supply drawing

so as to ensure a long seal and a good tolerance to fretting by agent.

The reliable contact of electric connection of a joint will mainly be affected by the joints of

components and parts, and it is also in relation to the material quality and dimensional precision of

the joint fitted with it on the harness.

1.4 Failure effects and judgment method
l Failure effects: spark extinction and poor idling etc.
l General Failure Reason:

1. Abnormal high voltage or inverse strong current occur during working;

2. The vacuum element is damaged during maintenance.

l Maintenance precautions: during maintenance, impinge using high pressure gas toward the

vacuum element is prohibited; when replacing the sensor after a failure is found, remember to

check if output voltage and current of the generator is normal.

l Simple measurement method:

1.4.1 Temperature sensor:

With the joint removed, turn the digital multimeter to Ohm shift, and then connect the two

meter pens respectively to 1# and 2# pins of the sensor; At 20

, the rated resistance should be 2.5

℃

kΩ±5%, and the other corresponding resistances can be measured out from the characteristic curve

in above chart. Analogue method can also be used when measuring, i.e., use an electric drier to blow

the sensor (be careful not to be too close to the sensor), and then observe the change of the sensor

resistance. At this point, the sensor resistance should fall.

1.4.2 Pressure sensor:

With the joint connected, turn the digital multimeter to DC Voltage shift, and then connect the

black pen to ground while the red pen respectively to 3# and 4# pins. Under idle speed state, 3# pin

should have a 5V reference voltage while the voltage on 4# pin should be around 1.3V (the actual

value depends on the model); Under no load state, when opening the throttle slowly, the voltage on

4# pin may change little; when opening the throttle rapidly, the voltage on 4# pin may reach around

4V instantly (the actual value depends on the model) and then fall to around 1.5V (the actual value

depends on the model).

2. Tachogenerator of Engine

2.1 Function of the sensor:

As one of the uppermost sensors of engine, the tachogenerator of engine provides ECU with rev

signal, acceleration signal and crank angle signal etc. of engine. ECU will calculate injection

pulse-width, injection time and ignition timing through these signals and provide the instruments

with rev signal of engine.

2.2 Principle of the sensor:

The inductive tachogenerator work together with pulse disc, it is used in ignition system

without distributor providing engine speed and crank shaft top dead center information.

Inductive tachogenerator is made up of a permanent magnet and coil outside of magnet.

Pulse disc is a tooth disc with 60 teeth originally but there are two teeth opening. Pulse disc is

assembled on crank shaft and rotate with crankshaft. When the tooth tip passes through closely the

end of the inductive engine tachogenerator, the pulse disc made of the ferromagnetic material will

cut the line of magnetic force of the permanent magnet in the inductive engine tachogenerator to

generate inductive voltage in the coil as engine speed signal output.

Tachogenerator

1. Shielded wire 2. Permanent magnet

3. Housing of sensor 4. Installation bracket

5. Soft magnet core 6. Coil

7. Air gap 8. 60-2 gear ring

2.3 Parameters of technical features

Value

Item

Min.

Typical

Max.

Unit

Resistance under a room temperature of

20

°

C

774

860

946

Ω

Inductance

310

370

430

mH

Output voltage at a crankshaft

revolution of 416rpm

>

1650

mV

2.4 Installation attentions:
l For the inductive tachogenerator, it is permitted to take out from its pack before it is assembled

to the auto or testing device right away.

l Inductive tachogenerator is assembled by press in method but not hammer tapping.
l Partly micro-encapsulated bolt M6

×

12 for fixing of the inductive engine tachogenerator is

recommended.

l The tightening torque is 8

±

2Nm.

l Gas clearance between inductive tachogenerator and pulse disc tip is 0.8-1.2mm.

Dimension d (see the figure below): 4.7mm.

2.5 Failure effects and judgment method:

l

Failure effects: start failure etc.

l General cause of the failure: man induced failure.
l Maintenance precautions: during maintenance, the tachogenerator should be installed by using

press-in method instead of hammering method.

l Simple measurement method:

1. With the joint removed, turn the digital multimeter to Ohm shift, and then connect the two

meter pens respectively to 2# and 3# pins; At 20

, the rated resistance should be 860Ω±10%.

℃

2. With the joint connected, turn the digital multimeter to AC Voltage shift, and then connect the

two meter pens respectively to 2# and 3# pins of the sensor; start the engine and voltage output

should be present at this point. (Inspection with vehicle oscilloscope is recommended).

Oscillogram in Test

In

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a

ll

a

ti

on
o

f t

h

e

tac
ho
g

e

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e

ra

tor

3. Phase Sensor

3.1 Function of the sensor:

Provide ECU with phase signal, i.e. help crankshaft position sensor of engine to judge it is then

at compressing top dead center or air exhaust top dead center.

3.2 Principle of the sensor:

The phase sensor is consisted of the Hall generator installed on the valve cover and the signal

wheel machined on the intake camshaft. When the camshaft rotates, the signal wheel will make the

magnetic flux passing the Hall generator change, thus generating a variable Hall signal.

3.3 Effects and judgment method:
l Failure effects: over proof emission and fuel consumption rise etc.
l General cause of the failure: man induced failure.
l Simple measurement method:

(connect the joint) switch on ignition switch but do not start the engine; put digital multimeter on DC

volt shift, connect two meter pen to No. 1 and No. 3 sensor connectors and make sure there is 12V

reference voltage. Start the engine, check if it is in good conditions of No.2 pin by oscillograph on

vehicle.

4. Water Temperature Sensor

4.1 Function of the sensor:

The water temperature sensor simultaneously provides ECU and instruments with water

temperature signal. ECU will calculate and regulate injection pulse-width and ignition advance angle

through water temperature signal. In addition, through water temperature signal, ECU also can

control turn-on and turn-off of cooling fan to prevent engine from damage caused by overheat.

4.2 Principle of the sensor:

The water temperature sensor is a minus temperature coefficient type electric resistance model

sensor; the higher the temperature is, the less the resistance will be. But, temperature rise and

resistance fall are not in linear relation.

Ground site

Phase sensor

87# pin of main relay

4.3 Parameters of technical features

(1) Data limit

Item

Value

Unit

Rated voltage

Can only be run by ECU

Rated resistance at 20℃

2.5

±

5%

k

Ω

Range of running temperature

-30 to +130

℃

Max. measuring current passing the

sensor

1

mA

Permissible vibration acceleration

600

m/s

2

4.4 Installation attentions

Coolant temperature sensor is installed on the cylinder body and the copper heat conducted

socket is inserted into coolant. There are thread on the socket, and screw in coolant temperature

sensor onto the threaded hole on cylinder block by the hexagon head of the socket. The maximum

permissible tightening torque is 15Nm.

4.5 Failure effects and judgment method
l Failure effects: starting difficulties etc.
l General cause of the failure: man induced failure.

l

Simple measurement method:

With the joint removed, turn the digital multimeter to Ohm shift, and then connect the two

meter pens respectively to 1# and 2# pins of the sensor; At 20

, the rated resistance should be

℃

2.5kΩ±5% and the others can be measured out from the characteristic curve in above chart.

Analogue method can also be used when measuring, i.e., dip the working area of the sensor in boiled

water (dip for adequate time), observe the resistance change of the sensor, at this point, the resistance

should fall to 300Ω-400Ω(the actual value depends on the temperature of the boiled water).

Coolant temperature
sensor

5. Knock Sensor

5.1 Function of the sensor:

The knock sensor provides ECU with knock signal. When the engine generates knock, ECU

will control to gradually reduce ignition advance angle to eliminate the knock; when no knock

occurs during certain strokes, ECU will gradually increase ignition advance angle to enable the

engine to obtain max. torque.

5.2 Principle of the sensor:

Knock sensor is a kind of vibrating acceleration sensor and is assembled on cylinder block.

Either single or multiple can be installed. The sense organ of the sensor is a piezoelectric element.

The vibration of cylinder block is transferred to piezoelectric crystal by mass block inside of sensor.

The piezoelectricity crystalloid gets pressure from mass block vibration, producing voltage on two

polar and transferring vibration signals to voltage signal and output it. See the following frequency

response characteristic curve. Because the frequency of knock vibration signal is much higher than

the normal engine vibration signal, the ECU can separate the signal into knock signal and non-knock

signal.

5.3 Attentions

Knock sensor has a hole in the middle, through which it is fastened on the cylinder by a M8 bolt.

For the aluminum alloy block, using long bolt with 30 mm; for the casting iron, using 25mm bolt.

The tightening torque is 20

±

5Nm. The installation position should ensure that the sensor is liable to

receive vibration signals from all cylinders. Decide the optimal installation position of knock sensor

through modal analysis to the engine body. Generally, for a 4-cylinder engine, the knock sensor is

installed between 2# cylinder and 3# cylinder; for a 3-cylinder engine, it is installed at the center of

2# cylinder. Do not let liquid such as engine oil, coolant, brake fluid and water etc. contact the sensor

long. Use of gasket of any type is not allowed in installation. The sensor must cling to the cylinder

tightly through its metal surface. During wiring of sensor signal cables, do not make the signal

cables resonate; otherwise, they may break. Be sure to prevent turning on of high voltage between 1#

and 2# pins of the sensor; otherwise, damage to the piezoelectric element may occur.

5.4 Effects and judgment method

Failure effects: poor acceleration etc.
l Reasons for general failures: long time contact of liquid such as engine oil, coolant, brake fluid

and water etc. with the sensor, which may corrode the sensor.

l Maintenance precautions: (see installation attentions)
l Simple measurement method: (remove the joint) put digital multimeter at ohm shift, and contact

the No. 1, No. 2 and No. 3 pin with its two meter pens. The resistance value should be more

than 1MΩ¸ under normal temperature. Leave the digital multimeter at millivolt shift, and tap

around the sensor using little hammer, there should be voltage signal output.

6. Electric Throttle Body

6.1 Function:

The electronic throttle body can automatically open or close the throttle according to the

driver’s will to apply the accelerator pedal to let the engine work under the corresponding operating

mode. The electronic throttle has cancelled the conventional throttle guy and the opening of throttle

is controlled by ECU based on the signal from accelerator pedal and other signals (such as A/C,

power assisted steering, back and gearshift etc.) through an electronic step motor inside the

electronic throttle body. In addition to cancel of conventional idle speed by-pass and idle speed step

motor, there are also throttle position sensors on the electronic throttle body to feed back the opening

of the throttle. This suite of throttle position sensor is different from the common one; totally two

suites of throttle position sensors are installed inside the electronic throttle body to monitor

rationality of the signals from the latter; when any problem occurs in a certain signal, ECU can still

use the other suite of signals to work on.

6.2 Working principle:

The throttle driving motor is a micro motor, which is composed of multi steel stators in a circle

and a rotor, with one coil on each steel stator. The rotor is a permanent magnet with a nut at its center.

All stators coils are constantly power on. As long as the direction of current of one coil is changed,

the rotor will turn a certain angle. When the directions of current of all stator coils is changed in a

proper order, a rotating magnetic field is formed, which will drive the rotor made from permanent

magnet rotate along a certain direction. Its principle is just that of a micro direct current motor.

This motor drives a suite of special gear reducing mechanism and a bidirectional spring; when

the system is under power off condition, this mechanism can ensure that the opening of throttle valve

plate maintains at a safe position where is bigger than that for idle speed but not too high, so that the

vehicle can continue to run; if engine ECU has entered this failure mode, when applying the

accelerator pedal, the valve plate of the electronic throttle body will no longer act.

电子节气门

6.3 Failure diagnosis:

ECU can monitor short-circuit and break of coil of the throttle driving motor, and light the engine

failure light in case of such failure to let the engine enter failure mode, when the engine fails to

accelerate, has very poor driving performance and needs maintenance immediately.

7. Oxygen Sensor

7.1 Function of the sensor:

Oxygen sensor is one of the principal sensors on modern autos; it can feed back the mixture

strength by detecting oxygen content in exhaust gas. ECU will correct the mixed gas based on the

Electronic throttle

signals fed back by the oxygen sensor, i.e. control injection pulse-width to let the mixed gas always

maintain an approximately ideal air-fuel ratio (14.7:1).

7.2 Principle of the sensor:

Sensing element of oxygen sensor is a kind of ceramic tube with holes, and outside of tube

walls are surrounded by engine exhaust gas and inside is air. Ceramic sensor element is a kind of

solid state electrolyte with electrical heating tube inside (as shown in the figure).

The operation of the oxygen sensor is achieved by converting the concentration difference of

oxygen ion between inside and outside of the ceramic sensor element to the voltage signal output. It

bears the characteristic of solid electrolyte once the temperature of the ceramic sensor element

reaches 350

. Because of the particularity of its materials, the oxygen ion can pass the ceramic

℃

sensor element freely. Taking advantage of this characteristic, the concentration difference will be

converted to electric potential difference to form electric signal output. If the mixed gas is

comparatively thick, the oxygen ion thickness difference between inside and outside of the ceramic

tube will be higher and the potential difference will also be higher, then a mass of oxygen ion will

move from inside to outside, so, the output voltage is comparatively high (close to 800mV-1000mV);

If the mixed gas is comparatively thin, the oxygen ion thickness difference between inside and

outside of the ceramic tube will be smaller and the potential difference will also be smaller, then just

a few of oxygen ion will move from inside to outside, so, the output voltage is comparatively low

1. Cable 2. Dish washer 3. Insulation bush 4. Protective bush

5. Clamp fitting of heating element 6. Heating rod 7. Contact pad

8. Sensor seat 9. Ceramic probe 10. Protection sleeve

Cross-section view of oxygen sensor

Characteristic Curve of oxygen sensor at 600

°

C

O

u

tpu

t vo

lt

a

g

e

V

Excessive air-fuel ratio λ

(close to 100mV). The signal voltage will mutate near theoretical equivalent air-fuel ratio (λ=1), see

the figure above.

Every oxygen sensor bears a cable and the other end of the cable is the wire connector. The wire

connector of oxygen sensor produced by our company has four pins:

No.1 connects to the positive pole of heater power supply (white);

No.2 connects to the negative pole of heater power supply (white);

No.3 connects to signal negative pole (gray);

No.4 connects to signal positive (black).

7.3 Parameters of technical features
l The requirement to exhaust pipe: the segment of exhaust pipe in the area before the oxygen

sensor must be heated up rapidly. If possible, the exhaust pipe should be designed to be tilting

down to avoid accumulation of condensed water in front of the oxygen sensor.

l Do not inappropriately heat up the metal snap ring of the cable at oxygen sensor side, especially

after the engine is shut down.

l Do not apply purge fluid, oiliness fluid or volatile solid on connector of the oxygen sensor.
l The screw thread of the oxygen sensor is M18

×

1.5.

l The size of the hexagonal head wrench for the oxygen sensor is 22-0.33.

The tightening torque for the oxygen sensor is 40-60Nm.

7.4 Failure effects and judgment method
l Failure effects: poor idling, poor acceleration, over proof tail gas and excessive fuel

consumption etc.

l General causes of the failure:

1. Moisture entering inside of sensor, and when the temperature is changed, the pin will be

broken;

2. The oxygen sensor “intoxicates”. (Pb, S, Br, Si)

Maintenance precautions: application of cleaning fluid, oiliness fluid or volatile solid on the

oxygen sensor during maintenance is prohibited.
l Simple measurement method:

1. Remove joint, put digital multimeter to ohm shift, connect meter pen to No.1 (white) and

No.2 (white) pins of the sensor. The resistance value is 1~6

Ω

at constant temperature.

2. With the joint connected, under idle speed state, when the working temperature of the oxygen

sensor reaches 350

, turn the digital multimeter to DC Voltage shift and connect the two meter pens

℃

respectively to 3# (gray) and 4# (black) pins; at this point, the voltage should fluctuate rapidly

between 0.1-0.9V.

Main relay 者 87#

Oxygen sensor

8. Fuel Pump Assembly

8.1 Function of fuel pump:

Fuel pump is used to deliver the fuel in the fuel tank to inside the engine at a certain pressure

for combustion. It also needs to regulate the fuel pressure duly as required by system pressure (non

fuel return type). Generally, the system fuel pressure provided by fuel pump is around 3.5-4bar.

8.2 Operating principle of fuel pump:

The electrical fuel pump is comprised of the DC motor, vane pump and end cover (integrates

check valve, relief valve and anti-electromagnetic interference element) as shown in following

figure.

The pump and the motor are installed on the same shaft within same closed housing. The pump

and electromotor are full of gasoline for coolant and greasing inside of the casing. The accumulator

provide power to electric fuel pump via fuel pump relay, and the relay switches on electric fuel pump

only when engine starting and running. When the engine stops for some reason, the pump will stop

to run by itself.

The max pressure at the outlet of the electrical fuel pump shall be between 450 and 650 kPa,

depending on the relief valve. Because the system is a non fuel return system, the pressure of the

whole fuel system will be controlled by the fuel pressure regulator. The value is 400KPa in general.

The electric fuel pump has different flow to the engine’s request. In order to facilitate the

production, the electromotor revolutions of EKP13 series electric fuel pumps of the same structure

are adjusted by changing the coil’s number of turns, and thus the flow is adjusted. Therefore, do not

apply an electric fuel pump for one model to another at will.

8.3 Parameters of technical features

Under certain fuel supply pressure, the flow of the electric fuel pump is in direct proportion to

voltage. The fuel pumps used by complete vehicle manufacturers are different.

8.4 Installation attentions

EKP13 series electric fuel pump can only be used inside fuel tank. When installing the fuel

pump, the filter net at fuel inlet with mesh size not bigger than 60

µ

or arranged with the customer

must be installed. Be careful not to let the fuel jet from air vent spray on the filter net at fuel inlet,

fuel pump bracket or fuel tank wall. Be careful when carrying the fuel pump. First, be sure to protect

the filter net at fuel inlet from load and impact. The fuel pump should be taken out of the plastic

1. End cover of oil pump

2. Electromotor

3. Oil passage

4. Paddle pump

Cross-section view of electric fuel pump