Chery A15. Manual - part 250

 
- Basic fuel injection time 
The basic fuel injection time provides the relationship between engine displacement and spray 
nozzle throughput.  
- Storage battery voltage correction 
When the storage battery voltage changes, the voltage correction will guarantee the correct fuel 
quantity injected.  
 
6. Ignition control function 
The MT20-based system features closed-loop computerized control, sequential multi-injection, 
grouped direct ignition and three-way catalyst post treatment. 
Closed-loop control is adopted for the engine fuel supply and idle speed control which features 
the ability to accommodate any difference of the system and its relevant mechanical parts arising 
out of manufacturing and wearing so that the integrity of the car is achieved.  
The system divides the engine’s four cylinders into the two groups of 1-4 and 2-3 for 
independent ignition control; grouped control optimizes and simplifies the structure so that the 
component costs and manufacturing and processing costs can be reduced.  
The system uses three-way catalyst to conduct post treatment to the engine exhaust and turn it 
into harmless gas before it is emitted into the air. 
Three-dimensional figure for engine ignition 
 
 
 
 
 
 
 

 

As actane rating is low, the ignition advance 
angle shall be reduced to avoid explosion. 

At the same engine speed, the higher the engine load 
is, the

 

lower the ignition advance angle will be

.  

The higher the engine speed is, the farther the piston 
will move in the same period, the higher the air 
mixture pressure and temperature will be, the quicker 
the combustion will be and the higher the ignition 
advance angle will be.  

 
 
 
 
 
 
 
 
 
 
 

Three-dimensional Figure for Engine Ignition Timing 

 
 
 

 

 
 
 

 

 

0

-30

-60

-90

-

120

30

60

90

120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

630

660

690

1缸

曲轴转角

58X

曲轴信号

1-4 缸线圈

 A

线圈驱动

2-3 缸线圈

 B

线圈驱动

1 缸工况

3 缸工况

4 缸工况

1 缸进气门开启

1X

凸轮信号

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

2 缸工况

1 缸喷嘴

 A

喷嘴驱动

4 缸喷嘴

 C

喷嘴驱动

3 缸喷嘴

 B

喷嘴驱动

2 缸喷嘴

 D

喷嘴驱动

20

15

10

5

25

30

35

40

45

50

55

5

10

15

20

25

30

35

40

45

50

55

5

10

15

58X

  

齿 数

补偿喷油脉冲

正常喷油脉冲

MT20

/

点顺序喷射分组点火发

动机管理系

统

控制时序图

多

Control Timing Figure for MT20 Sequential Multi-injection 

Grouped Ignition Engine Management System

 

1 缸工况：Cylinder 1 working condition  
3 缸工况：Cylinder 3 working condition  
4 缸工况：Cylinder 4 working condition  
2 缸工况：Cylinder 2 working condition  
压缩行程：Compression stroke 
进气行程：Intake stroke 
排气行程：Exhaust stroke 
作功行程：Power stroke 
1 缸进气门开启：Air intake valve of cylinder 1 open 

 

1 缸喷嘴喷嘴驱动 A：Cylinder 1 nozzle drive A 
3 缸喷嘴喷嘴驱动 B：Cylinder 3 nozzle drive B 
4 缸喷嘴喷嘴驱动 C：Cylinder 4 nozzle drive C 
2 缸喷嘴喷嘴驱动 D：Cylinder 2 nozzle drive D 
正常喷油脉冲：Normal fuel spraying pulse 
补偿喷油脉冲：Compensational fuel spraying pulse 
1-4 缸线圈线圈驱动 A：Cylinder 1-4 coil drive A 
2-3 缸线圈线圈驱动 B：Cylinder 2-3 coil drive B 
1 缸曲轴转角：Cylinder 1 crank shaft turning angle 
齿数：Number of teeth 
曲轴信号：Crank shaft signal 
凸轮信号：Cam signal 
Coil magnetization control 
The time for ignition coil magnetization determines the ignition energy of the spark plug. Too 
long a magnetization time will damage the coil or coil drive while too short a magnetization time 
will result in combustion.  
Startup mode 
Under the startup mode, the system uses a fixed ignition angle to ensure that the air mixtures in 
the cylinder will be ignited. When the engine speed goes up, the ignition angle will exit the 
startup mode.  
 
 
7. Calculation of ignition advance angle 

主 点 火 角

气 温 修 正

怠 速 修 正

空 调 修 正

水 温 修 正

减 速 断 油

修         正

海 拔 修 正

点 火 提 前 角 计 算

点 火 提 前 角

动 力 加 浓

修         正

加 速 修 正

 
Calculation of ignition advance angle（从主点火角开始顺时针翻译） 
Main ignition angle 

Deceleration fuel cutoff correction  Higher ARF correction 

Air conditioner correction 

Acceleration correction 

Ignition advance angle 

Idle speed correction  Altitude correction  Ambient temperature correction 
Water temperature correction 
- Main ignition advance angle 

 

After the engine water temperature becomes normal, the main ignition angle when the throttle 
opens is usually the minimum ignition angle or knock critical point (KBL) at the maximum 
brake torque; the ignition angle when the throttle closes shall be smaller than the MBT point to 
acquire stable idle speed.  
On the prerequisite that the cool driving performance is not affected, the basic angle may not be 
MBT or KBL ignition angle during heating of the catalyst and shall be delayed for as long as 
possible in order to ignite the catalyst as soon as possible.  
- Ignition advance angle correction 
Water temperature correction, air intake temperature correction, altitude compensation correction, 
idle speed correction, acceleration correction, higher ARF correction, deceleration fuel cutoff 
correction, air conditioner control correction, waste emission recycling correction 
- Acceleration correction 
Ignition advance angle deceleration correction is used to reduce the engine speed fluctuation 
caused by transmission system vibration and eliminate the knock caused during acceleration, 
thus smoothing the acceleration.  
- Higher ARF correction 
The ARF will be increased to the LBT in order to obtain better power and torque. Therefore, the 
ignition advance angle may be corrected to obtain the MBT point.  
-Deceleration fuel cutoff correction 
When the deceleration fuel cutoff mode is exited, the ignition angle may be corrected to make it 
smooth for the throttle to close.  
- Air conditioner control correction 
When the air conditioner is turned off at engine idle speed, the ignition advance angle may be 
corrected to make it smooth for the engine speed to change.  
- Three-dimensional figure for ignition correction 

Air filling efficacy@TPS/RPM 

Air

 

filling efficacy with throttle 

opened@MAP/RPM 

Correction coefficient for air 
filling temperature

 
 
 
 
 
 
 
 
 
 
 
 
 

Optimal ignition advance 
angle

 
 
 
 
 
 
 

Higher ARF 

Air filling efficacy with throttle 
closed@MAP/RPM