Chery A11. Manual — part 176

Maintenance Manual for Chery · Windcloud

M7.9.7 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.

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
outputed 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
control 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 46 of ECU.

Troubleshooting: blockage or crack of
carbon canister causes the increase of air
intake.

12

Maintenance Manual for Chery · Windcloud

M7.9.7 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 (KVS-S) and injector (EV).

Installation requirement: connect fuel
inlet/outlet pipes with rubber pipes and
fasten them down wtih 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

13

Maintenance Manual for Chery · Windcloud

M7.9.7 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 certian 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
repair at maintenance station so as to avoid the embarrassment of breaking down on highway

14

Maintenance Manual for Chery · Windcloud

M7.9.7 EFI System

or outdoors. Once failure is identified disappeared, the use of normal data will be restored.

(6). Failure Alarm
Some vehicles equipped with M7.9.7 system have fault indicating lamps. In case failure
occurs with relevant failure mark being set on some important parts such as ECU, manifold
absolute pressure sensor, throttle position sensor, coolant temperature sensor, knock sensor,
oxygen sensor, phase sensor, injector and two driver stages of idle speed actuator stepper
motor, carbon canister control valve and fan relay, ECU will alarm by lighting up fault
indicating lamp until the said failure mark restores. 

(7). Failure Readout
Failure information record can be called up either from electronic control unit through scanner,
or from flash code output. If failure involves the function of proportion regulator of fuel/air
mixture, the engine shall operate at least 4 minutes to read failure information record.

Figure 3-1: ISO 9141-2 Standard Diagnosing Connector



Connection of Scanner
This system adopts “K” wire communication protocol and ISO 9141-2 standard diagnosing
connector, see figure 2.5 below. The standard diagnosing connector is fixed on engine wire
harness, with Pin 4, 7 and 16 engaged on Engine Management System EMS. Pin 4 of
standard diagnosing connector is connected to ground wire of the vehicle, Pin 7 is connected
to Pin 71 of ECU (K wire of engine data), and Pin 16 to anode of accumulator.

Connecting steps: turn on ignition switch but do not start engine, ground Pin 7 of ECU with
K wire for at least 2.5 seconds and then stop grounding, the code lamp will start flashing.
After K wire is grounded for more than 2.5 seconds, code lamp will flash to output P-CODE
values. For example, for code P0203 the lamp will output in this way: continous 10 flashes –
pause – continous 2 flashes – pause - continous 10 flashes – pause – continous 3 flashes.

(8). Clearance of Failure Information Record

After elimination of failure, failure information record in memorizer shall be cleared.
When ignition is switched on, in case a failure occurs but dose no continue to the end of
stabilization time, the failure information will not be recorded.
 When the value of frequency counter Hz reaches 0, the failure information record of failure

15