Chery A11. Manual - part 154

Maintenance Manual for Chery·Windcloud

Marelli EFI System

4. Knock Sensor KS

Purpose: this sensor is designed to provide
ECU with engine knocking information so
as to carry out knocking control. When
engine detects a knocking signal, ECU
automatically delays ignition; when
knocking disappears, ECU automatically
brings forward the ignition advance angle
until knocking reoccurs. ECU keeps
repeating these steps.

Composition and principle: knock sensor
is a sort of vibration acceleration sensor,
which is fixed on cylinder block. ECU
controls engine ignition via signals detected
by pressure-sensing element.

Failure diagnosis: ECU monitors on
various sensors, actuators, power
amplification circuits and sensing circuits. In
case any of the following situations occurs,
failure mark of the knock sensor is set.
Knock sensor failure
Knocking control data processing circuit
failure
Cylinder-detecting signal is unreliable
After failure mark of knock sensor being set,
knocking closed-loop control is shut down,
reducing a safety angle from the ignition
advance angle stored in ECU. When error
frequency cuts down to below setting value,
failure mark restores.

Installation hint: tightening torque is
20±5Nm.

Troubleshooting: mainly check if there is

short circuit or open circuit on the

connection between 2 lines on sensor and

corresponding ECU pins.

If gasket is added during installation; if

tightening torque is proper.
If there is stitching defect between sensor
and cylinder, or there is foreign matter

between them.

Knocking block

2. Casing

3. Piezoelectric ceramics
4. Contactor
5. Electric connection

Knock sensor with cable

Knock sensor

Circuit diagram of knock sensor

Pins:

1 Knock sensor signal + (ECU 56#)
2

Knock sensor signal - (ECU 70#)

3 Knock sensor shield (ECU63#)

Caution: gaskets, water or oil between
sensor and cylinder are strictly prohibited.

Maintenance Manual for Chery·Windcloud

Marelli EFI System

5. Oxygen Sensor
Purpose: this sensor is designed to provide

the information that if there is surplus

oxygen after full combustion of fuel, which

is injected into engine cylinder in the intake

air. ECU, when applying this information,

can carry out fuel quantitative closed-loop

control so as to achieve utmost conversion

and purification of the three major toxic

elements in the engine exhaust with the

application of three-way catalytic converter.

Note that installation of three-way catalytic

converter will costs some of engine power.
Composition and principle: the nature of

oxygen sensor is atomic battery, while

sensing element of oxygen sensor is a

porous ceramic pipe, the outer side of pipe

wall is surrounded by engine exhaust, while

inner side vents to atmosphere. According to

inside and outside oxygen concentration

difference, sensor figures out indirectly if

the fuel injection is in excessive quantity,

and then transfers the information to ECU,

and the ECU controls the injection again.

The working voltage of oxygen sensor

fluctuates between 0.1-0.9V, 5-8 variations

in 10 seconds is required; if lower than such

frequency value, it shows that the sensor is

aged, damaged or poisoned, and needs

replacement. The said sensor is

unrepairable.
Failure diagnosis: ECU monitors on

various sensors, actuators, power

amplification circuits and sensing circuits. In

case any of the following situations occurs,

failure mark of the oxygen sensor is set.

Accumulator voltage is unreliable

Manifold absolute pressure signal is

unreliable

Engine coolant temperature signal is

unreliable.

Injector driver stage failure

After oxygen sensor failure mark is set, fuel

quantification closed-loop control is shut

down, and the primitive fuel injection time

stored in ECU is used to carry out fuel

quantification.
Installation hints: the tightening torque of

oxygen sensor is 50-60Nm, a layer of rust

preventive oil shall be applied on mounting

screw thread of oxygen sensor after

replacing so as to prevent from incapable

removal in case of rust.

Troubleshooting: mainly check if the plug

connection of several wires on the sensor is

in good condition, and if there is short

circuit or open circuit.

Generally, sensor damage is caused by

plumbum and phosphorus poisoning, so

pay attention to fuel quality, meanwhile

excessive consumption of engine oil is

liable to result in sensor failure.

Main relay

Oxygen
sensor

Circuit diagram of oxygen sensor

Oxygen sensor has a cable, the other end of
which is electric connection. The outside of
sensor is wrapped with asbestos fireproof
covering.
There are 4 pins on the joint:

1# connecting with sensor signal anode

(ECU 20#);

2# connecting with sensor signal cathode

(ECU 9#);

3# connecting with power supply and main

relay;
4# connecting with heating control (ECU
28#).

Interior structure of oxygen sensor

Maintenance Manual for Chery·Windcloud

Marelli EFI System

6. Electronic Control Unit (ECU)

Purpose:  ECU is the core of electronic
engine control system. Sensors sent various
signals to ECU for electric control, and
then ECU controls operations of fuel
injector and ignition coil, etc. after internal
calculation, thus controlling working of
engine.

Normal operation voltage: 9-16V

Composition:  it has shielded casing and
printed circuit board, which integrates lots
of electronic control units for the control of
EFI system.

Installation:  to be fixed by the support of
bracket under pilot trench of front
windshield. Pay attention to waterproofing.

ECU

Functions:

Multipoint sequential injection
Controlling ignition
Idle speed control
Independent knocking control on
cylinder-by-cylinder basis (knock sensor);
Providing sensors with power supply:
5V/100mA
λ

closed-loop control with self-adaptation

Controlling carbon canister control valve
Air conditioning switch
Engine-fault indicating lamp
Fuel quantitative correction
Engine speed signal output
Speed signal input
Accepting engine load signal
Troubleshooting: due to the fact that ECU
(electric control unit) has low failure rate, so
generally it is not advisable to replace ECU
for troubleshooting on any problem. Failure
of components such as periphery circuit and
sensors shall be checked and solved firstly.
Do not replace ECU until all periphery
components are confirmed to be fault-free.

Caution: poor internal contact is common
with ECU connector of A-series EFI system.
Connector problems are not easy to be
detected from the appearance of connector.
It is recommended that the detecting probe
be inserted from the back of connector
without breaking of wires. Broken wires
shall be covered by a layer of glass cement
and then proof fabric.

Maintenance Manual for Chery·Windcloud

Marelli EFI System

ECU Pin Definition:

Connected to

Not in use

Air conditioning compressor relay control

Not in use

Engine speed signal

Oxygen sensor ground

Not in use

Power supply (ignition key)

Not in use

Air conditioner ON signal

Oxygen sensor signal (-)

Not in use

Vehicle speed signal

Not in use

Not

use

Electromagnetic carbon canister valve
control

Dual-way anti-theft wire

Rotational speed sensor signal (+)

High speed fan relay control

Coolant temperature sensor ground

Injection relay control

Air intake temperature signal

Not in use

Knock sensor signal (+)

Not in use

Idle speed stepper motor C

Not in use

Idle speed stepper motor D

Not in use

Ignition coil control (1, 4)

Oxygen sensor (+)

Throttle position sensor power (+5V)

High speed fan request

Not in use

Coolant temperature sensor signal

Not in use

Knock sensor ground

Not in use

Idle speed stepper motor B

Diagnose (serial K wire)

Idle speed stepper motor A

Fault indicating lamp control

Ignition coil control (2, 3)

Power supply ground

Rotational speed sensor signal (-)

Power supply ground

TEMP sensor power (+5V)

ECU power (12V)

Not in use

Knock sensor signal (-)

Not in use

Injector control 1

Not in use

Injector control 4

Not in use

Low speed fan request

Pressure sensor signal

Not in use

Throttle position sensor signal

Not in use

Rotational speed sensor ground

Not in use

Injector control 3

Not in use

Injector control 2

Low speed fan control relay

Not in use

Content .. 152 153 154 155 ..