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Chery Fora (Elara A520). Manual - part 142

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Engine electronic control system schematic of ME7.9.7 chart 2.2

Chart 2.2

The basic component of ME7.9.7 engine electronic control system:

Electronic Control Unit(ECU)

Accelerator

Electronic Throttle Valve

Air Quality Flow Meter

Injector

Electronic Fuel Pump

Coolant temperature sensor

Fuel Pressure Regulator

Throttle position sensor

Fuel Pump Bracket

Camshaft Position Sensor Fuel Distributing Pipe

Speed Sensor

Oxygen Sensor

Canister Control Valve

Knock Sensor

Ignition Coil

Canister Control Valve

Ignition Coil

Phase Sensor

Air intake temperature sensor

Fuel Distribution Pipe Assembly

Front Catalytic Converter

Oxygen Sensor

Main Catalytic Converter

Speed Sensor

Knock Sensor

Temperature Sensor

UAES Parts

Electric Fuel Pump

Accelerator Pedal

Throttle Valve

Diagnosis Access

Anti Theft

Trouble Light

Electronic Accelerator

Onboard Diagnosis (Europe)

Returnless Fuel Supply System

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

ME7.9.7 engine management system is an electronic gasoline control system, and it can
provide lots of control characters about operator and vehicle or equipment. The system adopts
a combination method of open loop and closed loop (feed back) control to provide all kinds
of control signal to engine. The main function of the system:

1) The basic functions of applying physics mode engine

u For the system structure based on torque, the airflow sensor will confirm the loading

of cylinder and improve the mixture air control function closed loop control.

u Fuel injects ignition timing on the order of cylinder order, including knock control

and emission control functions.

u 3 way catalytic convert heating

u Canister control

u Idle speed control

u Limping home

2.2. CONTROL SIGNAL: ME7.9.7 SYSTEM INPUT/OUTPUT SIGNAL

The main sensor input signal of ECU of ME7 system:

l Air flow signal

l Throttle valve corner signal

l Coolant temperature signal

l Engine speed signal

l Phase signal

l Knock sensor signal

l Oxygen sensor signal

l Speed signal

l Air conditioner pressure signal

The above information after the transaction of ECU, there will generate required actuator
control signal, and this signal will be magnified in output driving circuit and was transferred
to its corresponding actuator. The signals include below information:

l Injection timing and injection continuous time

l Fuel pump relay

l Opening degree of canister control valve

l Ignition coil closing angle and ignition angle of advance

l Air conditioner compressor relay

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Cooling fan relay

2.3. INTRODUCTION OF SYSTEM MALFUNCTION DIAGNOSIS FUNCTION

2.3.1. MALFUNCTION INFORMATION RECORD

The  ECU  monitors  sensor,  actuator,  related  circuit,  malfunction  indicator  and  accumulator
voltage  etc.,  and  EUC  itself  continuously.  At  the  same  time  the  ECU  inspect  the  reliability
test  on  sensor  signal  output,  actuator  driving  signal  and  internal  signal  (e.g.:  closed  loop
control, coolant temperature, knock control, idle engine speed and accumulator voltage etc.).
ECU  will  set  the  malfunction  record  on  RAM  malfunction  memory  immediately  once  the
malfunction  or  the  unlikelihood  signal  is  detected.  The  malfunction  information  is  recorded
by malfunction code and displayed according to its appeared order, dividing malfunction into
“steady malfunction” and “contingency malfunction” (for example the malfunction is caused
by short time cable braking or bad contact of the inserts) according to its appeared frequency.

Chart 2.4 EFI System Malfunction Diagnosis Principle Chart

2.3.2, CONTROL STRATEGY OF FAILURE LAMP

When there is no trouble:

★ The failure lamp is lighting and die out within 4 seconds after the ignition switch is ON

★ Starting within 4 seconds, the failure lamp dies when the engine speed signal is found;

★ The failure lamp winking at 2HZ frequency when the K cable contact to ground more

than 2.5 seconds.

When there is a trouble:

★ The failure lamp always on light when the ignition switch is ON;
★ Start and die out when the engine speed signal is detected; if the failure lamp was defined

as lighting mode, it will always on light after reach its confirmed conditions;

Function Diagnosis

ECU

Actuator

Sensor

Control Order

Data Collection

Engine

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

★ Output winking code that is P-CODE value after the K cable contact with the ground

more than 2.5 seconds. For example: the winking mode of P0203 is: wink 10 times
continuously – intermission – wink 2 times continuously – intermission - wink 10 times
continuously – intermission – wink 3 times continuously.

2.3.3, DIAGNOSIS METER CONNECTION

This  system  adopts  “K”  cable  communication  protocol  and  use  ISO  9141-2  standard
diagnosis  joint,  please  see  chart  2.5.  This  standard  diagnosis  joint  is  connected  to  engine
harness fixed. The pins of No.4, 7 and 16 on the standard diagnosis  joint are used  for EMS.
The  pin  of  No.  4  on  standard  diagnosis  joint  is  ground  wire;  Pin  of  No.7  is  connecting  to
No.71 pin  of  ECU,  which  is  engine  data “K” cable; No.16  pin  is connecting  to  accumulator
anode.

Chart 2.5 ISO9141-2 Standard Diagnosis Joint

2.3.4, READ MALFUNCTION INFORMATION BY WINK CODE

Switch on  ignition  switch  and  use  engine data  K cable(that  is  standard  diagnosis  joint 7#)to
ground(use one lead connect pin of diagnosis joint 4# and pin of 7#) more than 2.5 seconds,
if  there  are  malfunction  code  in  ECU  malfunction  memorizer,  the  malfunction  light  wink
code  of  engine  now  is  P-CODE  value.  Such  as:  P0203  winking  type  is:  wink  10  times
continuously  –  intermission  –  wink  2  times  continuously  –  intermission  -  wink  10  times
continuously – intermission – wink 3 times continuously.

3. WORKING PRINCIPLE AND CHARACTER OF EFI SYSTEM ELEMENT

3.1 ELECTRONIC CONTROL UNIT - ECU

1)Exterior drawing

2)Purpose: ECU accepts and deals with engine status signals inputted from sensors and
drives the actuators to work. Making engine working as the established program, insure
power good, fuel consuming effectively and low emission.

3)Mounting position: Passenger compartment

4)Functions

l Multipoint injection in order

l Control ignition

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