Chery SQR 7160 sedan. Manual - part 124

 

 

 

 

 

 

 

 

 

 

 

Part II 

M&M MULTI-PORT ELECTRIC INJECTION ENGINE 

SYSTEM 

 

 

 

Operation And Maintenance Instruction  

For SQE480ED Engine Sequential Multi-port Fuel 

Injection System  

1. Description 

        SQR480Ed electric injection utilize M&M sequential multi-port fuel injection system 

which is of λSpeed Density Type ( engine speed, air density, air/fuel mixture control)  

and can control sequential fuel injection and distributor less ignition.   

        The system consists of 4 essential parts. 

        1：Air system  2：Fuel Supply System    3：Control system  4：Ignition system 

 

1.Fuel Tank 2.Fuel pump 3.Multi-function valve 4.Check valve 5.Fuel Feed Pipe 6.Engine 

ECU 7.Battery 8. Ignition switch  10.system relay  11.A/C compressor 12.Carbon 

canister solenoid    13.Fuse    14 Active carbon canister    15. Anti-theft unit    16.Absolute 

pressure and temperature sensor  17.Crankshaft speed and position sensor   18.Spark 

plug   19. Coolant temperature sensor   20. Fuel injector    21. Throttle position sensor   

22.idle step motor    23. Fuel rail      24. Air Filter      25. Ignition coil    26. Oxygen sensor 

27. Warning Indicator 28. RPM sensor    29. way catalyst converter    30. Knock sensor 

2. Operation Theory 

The system enable the actual measured air/fuel ratio to approach chemical reaction 

equivalent proportion, protecting 3 way catalyst converter and reducing exhaust pollution. 

Oxygen sensor real-time analyzes oxygen content of exhaust , which enables ECU to 

Fig 1    SQR480ED Electric Injection System Theory Illustration 

 

 

correct air/fuel ratio by controling    injected fuel quantity. 

        Fuel is directly sprayed into intake manifold beside the intake valve under pressure of 

3.5bar. The fuel injector of each cylinder takes correspondingly phase control upon 

sequence of air intake and open time of intake valve. Injection terminal is stored in ECU 

MAP Diagram and will change with engine speed and intake manifold pressure. ECU can 

correct all basic control strategy of engine under all operation condition upon signals from 

various    sensors in the system.   

        Idle speed is kept steady by step motor controlling by-pass valve opening and changing   

ignition advance angle. Idle speed cannot be regulated manually. 

        The system utilize inductive discharge ignition, and control time is managed by power 

supply module in ECU. Advance angle of ignition is calculated upon engine compression 

pressure ratio and air intaked. 

3. Fuel Injection System Control Strategy   

    3.1 Start-up 

    During the start-up of engine, ECU injects fuel to all cylinders simultaneously to 

reduce start-up time, and then injects in phase sequence.   

        3.2 Idle speed 

        After start-up, engine needs idling for several minutes to warming up. The normal idle 

speed is 880±50rpm(coolant temperature≥85℃). When engine is cold, engine runs at a 

high idle speed warming up under the ECU control. With rising of coolant temperature, idle 

speed decrease to normal speed gradually. When engine idles, if A/C is turned on, ECU will 

increase idle speed by 100rpm.   

    3.Accelarating 

    During accelerating, ECU adds fuel injection upon engine load increasing and handles 

signals from throttle position sensor, intake manifold absolute pressure sensor and Top Dead 

Center/speed sensor. “ Basic Injection Time” multiplies a correction coefficient calculated 

upon engine coolant temperature, throttle opening rate and intake manifold pressure 

increment. When the injector is closed, if fuel injection time is calculated to have an abrupt 

change, ECU will add fuel injection time according to above-mentioned factor, namely 

reopen injector and compensate fuel injection as much as possible.   

    4.  Decelerating  

    During decelerating, engine should reduce fuel injection to decrease exhaust pollution. 

ECU identify this stage by high level to low level throttle potentiometer signal but not to 

idle speed, and using buffer strategy to reduce torque output. When throttle potentiometer 

signal shows throttle is closed and engine maximum limit speed reaches, ECU will regard 

the condition is met and reduces by-pass air charge by step motor.   

    5. fuel cuttingoff 

        ECU will carry out fuel cutting-off stragety when    warm engine speed is over 150rpm 

and an idle speed position throttle (throttle potentiometer signal) is identified. During engine 

warming up, ECU takes an engine speed of which engine water temperature increasing 

 

strategy works. When throttle is not closed and warm engine speed is less than 1400rpm, it 

will recover fuel supply.   

    6. Full load 

        When engine is under full load, ECU will prolong basic injection time to obtain the 

maximum output power and guarantee 3 way catalyst converter temperature is within 

specification. 

        7.Speed    limit   

    When engine speed exceeds threshold valve for10 seconds or instantaneously exceeds 

a specified threshold value , ECU will stop injection control function. When speed returns 

to normal, ECU restart injection control.   

8. Atmosphere pressure correction 

The atmosphere pressure changes with altitude, which brings change of volume 

efficiency.and needs to correct the basic calibration (injection time and by-pass air charge).   

    9. Self-adapting 

    ECU has air/fuel ratio self-adapting ability and can stores difference between basic 

MAP diagram and correction value of oxygen sensor during operation. These differences 

will be stored permanentlyallowing system and components to be correct gradually as a new 

one. This function contains automatic conformance check and automatic diagnosis of 

memory parameter. 

    10. Power balance  

        When normal electrical components operating cause battery voltage below 12.2V, the 

electricity demand of electrical components is over than generator ability. ECU will 

gradually increase engine idle speed to generate enough electricity energy. When power 

balance is positive, increased idle speed will cancel.   

4. Structural composition 

    4.1 Fuel supply system 

        The fuel supply system is semi-none-fuel-return type, only one pipe connecting fuel 

tank and fuel rail. The system has the following advantages:if accident occurs, the fire 

hazard possibility will be lowered to minimum by none-fuel-return pipe, little fuel vapor in 

fuel tank, low fuel temperature in fuel tank.   

The fuel supply system includes: electric fuel pump, diaphram fuel pressure regulator, 

fuel pipe, fuel filter, fuel rail, quick coupler, fuel injector etc.