Chery Fora (Elara A520). Manual — part 141

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

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EFI SERVICE MANUAL

A21 car is equipped with ME7.9.7 EFI system which developed by UAES. This manual will
introduce the general service and the operational principle and character of sensor elements
of EFI system in detail. At last there will be some diagnostic method and flow for the typical
problems.

1. NOTICE TO THE EFI SYSTEM SERVICE

1.1. GENERAL SERVICE

●

Digital multimeter is the only permitted instrument to inspect the EFI system.

●

Please use the quality spare parts for service, otherwise can not make sure the EFI work

properly.

●

Please use lead free gasoline during service.

●

Please be obedient to the service and diagnose flow.

●

It is forbidden to disassembly the EFI part during service.

●

It should be careful to take the electronic component (ECU, sensor, etc.) for preventing

from dropping to the ground.

●

Please protect the environment, deal with the rejectamenta carefully and effectively.

1.2. NOTICE DURING THE SERVICE

●

Do not disassemble any part or inserts of the EFI system from its original position at

random to prevent from damaging parts or that moisture and dirt oil come into the inserts.
And that will keep the system from working properly.

●

Please leave the ignition switch at shut off position when you disconnect and connect the

inserts otherwise it will damage the electric element.

●

It is must keep the ECU under 80℃, when you do the work of hot status simulation and

other works which may cause the temperature increase.

●

The supplying oil pressure is high(around 300kPa), all the fuel pipe is made up of anti

high pressure pipe. There is high pressure in fuel pipe even the engine does not run. So do
not disassemble the fuel pump at random when carrying out service for fuel system.
Before disassemble the fuel pipe please carry out discharge pressure procedure. The
method is as below: Disassemble the fuel pump relay (or disconnect the connector plug),
start engine at its idle running and it dies out by itself. After the service supply fuel to
engine fuel pipe at first, the method is: turn ignition key to ON position and wait a while,
repeat this four or five times. Disassembly of fuel pipe and fuel filter should be carried
out at a place with good ventilation and done by professional maintainer.

●

Do not give electricity to fuel pump when the electrical pump is taken out of fuel tank in

order to prevent from electrical spark and cause fire.

●

Fuel pump is not allowed to carry out running test at dry or water situation, which will

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

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decrease its life. And do not exchange anode and cathode of the pump.

●

Carry out jump spark inspection at necessary time when inspect the ignition system, and

the time to inspect must be short. Do not open the throttle valve to prevent a lot of
unburned gasoline entering exhaust pipe and damage the 3-way catalytic converter ( It is
better to take off the corresponding injector insert during the jump spark testing)

●

The adjustment of idle speed is done completely by EFI without manual work. The

accelerator stop screw of throttle valve has been fixed well in advance by manufacturer so
that it is not allowed to change it original position by the customer.

●

Do not exchange the anode and cathode of the accumulator to prevent damaging the

electronic component. This system uses cathode ground.

●

Do not disassemble accumulator cable when the engine is running.

●

Disassemble the cable of accumulator anode and cathode, and ECU when there is welding

work on the car.

●

Do not inspect the input and output signal of component by impaling the lead surface.

1.3. SERVICE TOOLS

Tool name:

EFI system diagnostic tester

Function:

Read/clear the breakdown code in EFI and
inspect data, test part motion.

Tool name:

Ignition timing lamp

Function:

Inspect engine ignition timing.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

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Tool name:

Digital multimeter

Function:

Inspect the character parameter of voltage,
current, resistance.

Tool name:

Fuel pressure gauge

Function:

Inspect the pressure in fuel system, judge the
status of fuel pump and fuel pressure
regulator.

Tool name:

Pressure gauge for cylinder

Function:

Inspect the pressure in every cylinder.

Tool name:

Fuel injector cleaner and analyzer

function:

Analyze and clean the injector.

Tool name:

Vacuum meter

function:

Inspect the pressure of intake manifold

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1.4. EXPLANATIONS OF THE ABBREVIATION IN THE MANUAL

DG Speed Sensor

DVE Electronic Throttle Valve

DR Fuel Pressure Regulator

FPM Accelerator Pedal

ECU Electronic Control Unit (Computer)

EKP Fuel Pump

EMS Engine Management System

EV Fuel Injector

LSH Heating Oxygen Sensor

KS Knock Sensor

KSZ Fuel Distributing Pipe Assembly

KVS Fuel Distributing Pipe

ROV Ignition System with Distributor

PG Phase Sensor

RUV Ignition System without Distributor

TEE Oil Pump Bracket Assembly

TF-W Coolant Temperature Sensor

TEV Purge Canister Control Valve

HFM Air Flow Sensor

ZSK Ignition Coil

2. ME7.9.7 SYSTEM INTRODUCTION

2.1. SYSTEM BASIC PRINCIPLE

2.1.1 SYSTEM GENERAL INTRODUCTION: ME7.9.7-MOTRONIC EMS

Engine management system (EMS)is composed mainly by three components: sensor, ECU,
and actuator. And these three parts control the intake air quantity, fuel injection quantity and
ignition advance angle. The basic frame is shown in chart 2.1.

Chart 2.1 compose of engine electronic control system

In engine electronic control system, the sensor is the input part used for measuring all kinds
of physics signal (temperature and pressure etc.) and change them to corresponding electronic
signal; the function of ECU is accepting the signal and calculate it according to the
programmed program and generate corresponding output signal to power drive circuit; and
the power drive circuit makes the engine running according to established strategy by driving
every actuator to do different action; at the same time the malfunction diagnosis system of
ECU monitors all parts or control function, and if a malfunction is detected and confirmed it
will memorize malfunction code, transferring “ limping home” function, and when the
malfunction is deleted, the normal value will be desterilized.

Diagnose

Sensor

ECU

Actuator

Engine

Diagnose