Chery S11 / Chery QQ. Manual — part 204

Chery QQ Maintenance Manual 372 EFI System

1

Chapter 1 The princple for EFI and actuator

1.Intake air pressure and intake
Temperature sensor
Usage: Measure baro pressure in manifold and
intake air temperature to supply laod information
for engine.
Constitute and pricinple:The sesor
Consisits of two sensors, MAP and IAT, which
mounted on voltage stablizer box.
MAP: Map consisits of one silicon chip that etched
a film on the chip. There are 4 piezoelectirc
resistances that consist of a Wiston bridge. The
information processing circuit is also on the chip.
The chip consists of closed reference space with a
metal shell. The air absolute pressure in the space
is nearly to zero.
In this way, a micro electric-mechnic system is
formed. The active face of the chip is endured a
pressure nearly to zero, and MAP pressure applies
on the back of the chip through a connecting pipe.
The thickness of the chip is only several microns
（

um），so the change of MAP pressure will

result the mechanical disform for the chip together
with 4 resistances to change their resistance.
The voltage signal that is linearity with pressure is
formed after processing by information processing
circuit in the chip.

Intake air pressure: IAT is a resistor with NTC.

Like coolant temperature sensor, the resistance
decreased with the temperature increasing. ECU in
engine monitors the change of intake air
temperature (conresponding in series circuit).
Diagnosis: The open, short or wear of sensor could
be ditected by the rear electronic unit of MAP.
ECU will judge the malfunction of sensor if the
out put signal exceeds the signal outside the curve
of output feasure.

For examle, if the intake air pressure is higher

than the up limit or lower than lower limit,ECU
will judge thar sensor is malfunction ( The intake
air pressure is below lower limit in starting, but
ECU can juge sarting condition), “CHECK
ENGINE”light will on at same time and engine
will run at malfunction mode. ( The light will not
on for all malfunctions).

MAP/ IAT

进气压力温度传感器

The circuit for MAR/IAT

MAR/IAT

Pins: No.1 Ground
No.2 Output signal of temperature
No.3 To 5V
No.4 Output pressure signal

Chery QQ Maintenance Manual 372 EFI System

2

The section plane of MAP/IAT
1.Seal 2. Stainless steel bush 3. PCB plate 4.
Sensor 5. Shell6. Support 7. Welding conncetion
8. Felt connection

2. TPS
Usage: TPS is used to supply Throttle angle signal.
According to this signal, ECU will receive enging
load signal and working condition signal such as
starting, idle, back up, partial load, and full load)
as well as acceleration and decelation signal.
Consititue and pricinple:TPS is a angle sensor with
linear output. It consists of 2 arc slide resistors and
2 slide arms. The shaft of arm and throttle shaft
connect to one axes. When running throttle, arm
run together and slides on resistor. Putout UP as
output voltage.
So it is a angle potetiameter. ECU use UP/US as
ratio to vioid the fluctuate of sensor value caused
by engine voltage fluctuate.
Diagnosis: ECU check if throttle angle exceeds
the up limit or lower Limit of output signal. If so,
ECU will judge TPS malfunction, engine will run
at malfunction mode, MIL will on( Knock sensor
or dirty will cause engine malfunction).
Install: Screw torque for bolts: 1.5Nm-2.5Nm

Out view of TPS

Pins:1. Volt output 2. Signal ground 3. Signal

output

节气门位置传感器

TPS

Diagram of TPS

3. ECT TF-W
Usage: ECT is used to supply Coolant temerature
information for the timing and fuel inject pulse
width control on engine start, idle, normal running.
Constitue and pricinple: ECT is a termal sensive
resistor with ntc. The resistance decreases with
coolant temperature increase, but it is nor linrearity.
The resistor is enclosed in copper bush. The
change of resistance is transformed into changing
voltage to ECU by a voltage distribute circuit to
monitor the change of water temperature.
Diagnosis: When coolant temperature is over up
limit, or below lower limit, MIL is on, engine run
at malfunction mode. ECU control ignition and
fuel inject according to set temperature. Fan runs
at high speed.
Limit data: 2.5±5%KΩ
Hint: Screw torque: 15±2Nm
Hint: There are 2 sensors in vehicle. One is single
pin water temperature and supply water
temperature signal for water temp meter; The other
is double pins and supply the temp signal to ECU.

Chery QQ Maintenance Manual 372 EFI System

3

Diagram of ECT

Pins: There are 3 pins which could be
interexchangable.
a. EFI water temperature signal pin, resistance

is 2.45KΩ at 200C.

b. Instrument water temperature signal pin,

resistance is 0.05KΩ at 800C.

c. Signal

ground

接仪表

b

Circuit diagram of ECT
Hint: There are 1 water temperature sensor with 3
lines on it. One is ower line, two are signal lines
which one to ECU and the other to instrument.

4. KS
Usage: Supply knock signal to ECU for knock
control.
Consititution and principle:
KS is vibration accelaration sensor mounted

onengine. The sense element is a piezoelectricity
element. The vibration of cylinder is transformed
to piezoelectrical crystal through mass block in

sensor. The pressure of crystal produce voltage on
two polar faces and change vibration signal into
output AC voltage signal.
Because the frequency of vibration caused by
engine knock is much higher than normal
frequency of engine vibration signal, so ECU can
distingquish knock and unknock signals after
filtering the signal of KS. When engine load, speed
and coolant temperature exceed gate value, and not
set KS malfunction information record, the signal
of KS will be used to close loop control for
knocking. When the control is actuated, the signal
of KS will input to ECU for integral after amplify
and filter.
When certain integral value in crank angle exceeds
gate value, ECU will consider the knock happens,
and reduce 1 degree of ignitionadvanced-angle. If
knock happens on next cycle, ECU will reduce 1
degree of ignitionadvanced-angle again; If no
knocks happen in next cycles, ECU will resume
the angle to normal value.
Diagnosis: ECU monitors each sensor, actuator,
power amplifier and check circuit. KS will mark
malfunction position once following situations
happen:

KS malfunction
KS control data process circuit malfunction
Cyinder identification signal is untrustable

After KS marks the malfunction position, knock
close loop control will shut off and reduce 1 safty
degree for ignition advanced-angle stored in ECU.
When wrong frenquency is below set value,
malfunction position will resume.
Hint: Screw torque 20± 5Nm

.

Chery QQ Maintenance Manual 372 EFI System

4

KS with cable

爆震传感器

The diagram of KS

Pins: pin 1 and pin 2 connect ECU
The shield wire of sensor is folded on outside of
signal wire.

5. Oxygen sensor
Usage: The sensor is used to supply the
information that if oxygen is superfluous after the
fuel in cylinder combused completely in intake
air.ECU uses the information to close-loop
control for quantitative fuel and transforms or
purifies three venomousnee ingredients such as HC,
CO and NOX in catalyzer.

Constitue and priciple: The sense element is a

ceramic pipe with bores. The outside of pipe is
surrounded by exhaust of engine, and inside is
touched with automosphere. The pipe wall is one
kind of solid electrolyte with electric heating pipe
in it to heat ceramic body to 300 Cº for ceramic
body to work.The oxygen ion can pass pipe freely.

The concentration diffrencial is transformed

into electric differencial with this feature to form
electric signal. If mix air is richer, electric
differencial and output voltage are higher; if mix
air is leaner, electric diferencial and output voltage
are lower.

The working voltage of sensor fluctuates

between 0.1-0.9V with 5-8 times every 10 seconds.
Sensor is aging if the frequency is below this value
and needs replacing. The sensor cannot be
repaired.
Disgnosis: ECU monitors each sensor, actuator,
power amplifier and check circuit. ECU will mark
the malfunction position for oxygen sensor once
one of following situations happen:
Battery voltage is not trustable.
MAP signal is not trustable.
Injector driver is fault.
After marking malfunction position for oxygen
sensor, fuel ration close-loop control will shut off
and will be carry on according to basic inject time
stored in ECU.
Install hint: The screw torque of sensor is
50-60Nm. Smear anti-corsion oil on sensor after
replacing.