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.
1.
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.
4
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
5
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.
6
Maintenance Manual for Chery·Windcloud
Marelli EFI System
ECU Pin Definition:
Pin
Connected to
Pin
Connected to
1
Not in use
41
Air conditioning compressor relay control
2
Not in use
42
Not in use
3
Not in use
43
Not in use
4
Engine speed signal
44
Oxygen sensor ground
5
Not in use
45
Not in use
6
Not in use
46
Not in use
7
Not in use
47
Power supply (ignition key)
8
Not in use
48
Air conditioner ON signal
9
Oxygen sensor signal (-)
49
Not in use
10
Not in use
50
Vehicle speed signal
11
Not in use
51
Not in use
12
Not
in
use
52
Electromagnetic carbon canister valve
control
13
Dual-way anti-theft wire
53
Rotational speed sensor signal (+)
14
High speed fan relay control
54
Coolant temperature sensor ground
15
Injection relay control
55
Air intake temperature signal
16
Not in use
56
Knock sensor signal (+)
17
Not in use
57
Idle speed stepper motor C
18
Not in use
58
Idle speed stepper motor D
19
Not in use
59
Ignition coil control (1, 4)
20
Oxygen sensor (+)
60
Throttle position sensor power (+5V)
21
High speed fan request
61
Not in use
22
Not in use
62
Coolant temperature sensor signal
23
Not in use
63
Knock sensor ground
24
Not in use
64
Idle speed stepper motor B
25
Diagnose (serial K wire)
65
Idle speed stepper motor A
26
Fault indicating lamp control
66
Ignition coil control (2, 3)
27
Power supply ground
67
Rotational speed sensor signal (-)
28
Power supply ground
68
TEMP sensor power (+5V)
29
ECU power (12V)
69
Not in use
30
Not in use
70
Knock sensor signal (-)
31
Not in use
71
Injector control 1
32
Not in use
72
Injector control 4
33
Not in use
73
Not in use
34
Not in use
74
Not in use
35
Low speed fan request
75
Pressure sensor signal
36
Not in use
76
Throttle position sensor signal
37
Not in use
77
Rotational speed sensor ground
38
Not in use
78
Injector control 3
39
Not in use
79
Injector control 2
40
Low speed fan control relay
80
Not in use
7
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