Chery A11. Manual — part 156
Maintenance Manual for Chery·Windcloud
Marelli EFI System
11. Carbon Canister Control Valve
Purpose: to be used for the control of purge
flow rate of carbon canister. Carbon canister
control valve is controlled by ECU in
accordance with engine load via the duration
and frequency of electric impulse (i.e. duty
ratio). Excessive accumulation of gasoline
vapor in charcoal canister will lead to
gasoline leakage and pollution, therefore,
the function of carbon canister
electromagnetic valve is to open the said
valve as appropriate so as to transfer
excessive gasoline vapor into air intake pipe
for combustion, in addition, the aforesaid
valve shall be opened at small and medium
load of engine, while closed at idle speed
and heavy load.
Composition and principle: carbon
canister control valve consists of solenoid,
armature and valve, etc. There is a filter
screen on inlet. And the airflow rate passing
through carbon canister control valve is
related to duty ratio of electric impulse
outputted by ECU to the said valve on one
hand, while related to pressure difference
between its inlet/outlet on the other hand. In
case there is no electric impulse, carbon
canister control valve will shut down. ECU
controls the said valve’s current-on time and
indirectly controls the rate of purge flow
according to signals provided by sensors of
engine.
Failure diagnosis: ECU functions failure
diagnosis on driver stage of carbon canister
control valve instead of the said valve. In
case short circuit, overload, short circuit to
ground or open circuit occurs on driver stage
of carbon canister control valve to
accumulator voltage, fuel rated closed-loop
control basic self-learning and idle speed air
requirement self-learning are shut down, and
the self-learning data are valid. If failure
occurs on the aforesaid valve, generally
engine shows instable idle speed or
excessive idle speed.
Carbon canister control valve
Main relay
Carbon canister electromagnetic valve
Circuit diagram of carbon canister control valve
TEV-2
Pins:
Pin 1 connecting with Pin 87 of output
terminal of main relay;
Pin 2 connecting with Pin 52 of ECU.
Troubleshooting: blockage or crack of
carbon canister causes the increase of air
intake.
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Maintenance Manual for Chery·Windcloud
Marelli EFI System
12. Assembly of Steely Fuel Distributing
Pipe
Purpose: to store and distribute fuel to
provide fuel injection system with a fairly
stable pressure environment, to achieve
counterbalance of supply pressure and fuel
feed of each cylinder as well as smooth
engine operation.
Composition: fuel distributing pipe
assembly is made up by fuel distributing
pipe and injector.
Installation requirement: connect fuel
inlet/outlet pipes with rubber pipes and
fasten them down with hoops. The size of
hoops used shall match that of rubber pipes
so as to ensure air-tight connection between
fuel inlet/outlet pipes and rubber pipes.
Failure diagnosis: generally, the probability
for failure occurrence of fuel feeding header
pipe is slim. Mostly, failure is caused by
improper assembling, which leads to leakage
in fuel system, therefore, be careful when
assembling: O-ring oil seal used can not be
reused; when assembling, apply some
lubrication oil as appropriate.
Fuel distributing pipe assembly
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Maintenance Manual for Chery·Windcloud
Marelli EFI System
13. Rotational Speed Sensor
Purpose: rotational speed sensor provides
engine ECU with rotating speed, rotating
angle and reference signals for control of
engine cylinder detection and ignition;
rotational speed sensor of induction type
combines with oscillator to provide engine
speed information and crankshaft top dead
center information in the distributor-less
ignition. Rotational speed sensor of
induction type is made up of a permanent
magnet and coils wound on magnet.
Oscillator is a fluted disc with 60 teeth
originally, except for 2 vacant teeth. It is
installed on crankshaft and rotates with it.
When tooth point passes from next to the
end of rotational speed sensor of induction
type, oscillator made from ferromagnetic
material cuts magnetic force lines of
permanent magnet of the aforesaid sensor,
generating induced voltage and outputting as
rotating speed signal.
Composition and principle: This vehicle
adopts rotational speed sensor of magnetic
pulse type, with coils winding around a slug
inside, signal wheel rotating at high speed
and cutting magnetic lines of force; induced
electromotive force is generated in coils,
while ECU, according to the frequency of
the said force generated, calculates engine
rotating speed for the use of engine control.
Installation requirement: clearance 20.5
mm (nonadjustable)
Coil resistance: 1150-1400 ohm
Failure diagnosis: engine ECU will identify
failure of crankshaft position sensor in case
that any of the following conditions occurs
in sensor:
Sensor line short circuit to ground;
Sensor line open circuit;
Sensor signal distortion.
After failure of rotational speed sensor is
identified, engine will not be started, and
fuel pump relay will not be ON.
Troubleshooting: check to see if sensor line
is normal;
Check to see if resistance in sensor is
normal;
Check if shielded line circuit is open.
Assembling schematic drawing for
crankshaft position sensor
Engine rotational speed sensor
Circuit diagram of rotational speed sensor
Pins: Pin 1 connecting with ECU’s 53# pin
(signal +)
Pin 2 connecting with ECU’s 67# pin
(signal -)
Pin 3 connecting with ECU’s 77# pin
(shielded line)
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Maintenance Manual for Chery·Windcloud
Marelli EFI System
Chapter Two: Basic Principle for EFI System Failure Diagnosis
(1). Failure Information Record
Electronic control unit constantly monitors sensors, actuators, relevant circuits, fault
indicating lamp and accumulator voltage, etc. and even electronic control unit itself, and
carries out reliability test on sensor output signal, actuator drive signal and internal signal (for
instance: oxygen closed-loop control, knocking control, idle speed control and accumulator
voltage control). Once a certain link is found failed, or a certain signal value is unreliable,
electronic control unit will make information record of failure immediately in failure
memorizer of RAM. Failure information record will be stored in form of failure code, and
displayed as per sequence of failure occurrence.
Failure, according to frequency of occurrence, can be divided into “constant failure” and
“random failure” (for example: failure caused by temporary wire harness open circuit or
poor contact of socket connector).
(2). Failure Status
If the continuance of an identified failure exceeds the stabilization time stipulated for the first
time, ECU collects it as a stable failure, and stores it as “constant failure”; if such failure
disappears, ECU stores it as “random failure” and “nonexistent”; if such failure is identified
again, then still it is “random failure”, but the “existent” history failure does not impact the
normal use of engine.
(3). Failure Types
Short circuit to power supply anode
Short circuit to on ground
Open circuit (on occasion that input stage has upward pull/downward pull resistor, ECU will
identify the open circuit failure at input port as input port failure of short circuit to power
supply anode or short circuit to ground)
Signal unreliable
(4). Four Types of Failure
Max. failure, signal exceeds upper limit of normal range.
Min. failure, signal exceeds lower limit of normal range.
Signal failure, no signal.
Illogical failure, signal exists, but illogical.
(5). Limp Home
For some important failures identified, whose duration exceeds stabilization time stipulated,
ECU will adopt software countermeasure as appropriate, for example: shutting down some
control functions of oxygen sensor closed-loop control and setting substitute value for
unreliable data considered. Although engine has relatively poor working condition, the car
can still run. The aim of this is to let the car get home after a fashion or have examine and
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