Geely Emgrand X7. Manual part — 26

2.2.3.3 ECM Controlled Ignition System

1. Closed Ignition Angle Control

The length of the closed ignition angle determines the spark plug ignition energy. Too long
ignition coil magnetizing will damage the coil or ECM internal ignition coil driving circuit, while
too short will cause ignition failure (misfire).

2. Start-up

Mode

In the start-up mode, the system uses a fixed ignition angle in order to ensure cylinder mixture is
ignited, and provide positive torque. When the engine starts to run, the engine speed increases to
the automatically running status while the ignition angle will no longer be in starting mode.

3. Ignition Advance Angle Calculation and Control

A. Main

Ignition

Advance

Angle

When the engine water temperature is
normal, with the throttle opening, the
main ignition angle is the minimum
ignition angle at the optimal torque
point or the threshold of knocking.
When the throttle is closed, the
ignition angle should be less than
optimal torque point for idle speed
stability. Without affecting the driving
with a cold engine, in order to reach
the normal operating temperature as
quickly as possible, in the catalytic
converter heating process, the basic
ignition angle can be one angle other
than the optimal torque point or the
threshold of detonation. This angle
should also be delayed as much as
possible without affecting the driving
ability.

B. Ignition Advance Angle

Adjustment

Temperature adjustment, intake air
temperature adjustment, altitude
compensation adjustment, idle speed
adjustment, acceleration adjustment,
power-enriched adjustment,
deceleration fuel cut-off adjustment,
Air-Conditioning control adjustment,
exhaust gas recirculation adjustment.

水温修正

怠速修正

主点火角

点火提前角

点火提前

角计算

气温修正

阀板修正

减速断油修正

加速修正

配气相位控制
的点火角补偿

动力加浓修正

空调修正

FE02-8039b

C. Acceleration

Adjustment

Ignition advance angle acceleration adjustment is used to mitigate the engine speed fluctuations
caused by drive system torque shock, and eliminate possible detonation during acceleration,
making the acceleration smoother.

D. Valve Timing-controlled Ignition Angle Compensation

In order to obtain a better power and torque, system will enrich the Air-Fuel ratio to achieve the
optimal torque and adjusts the ignition advance to achieve the optimal torque output.

E. Valve Timing-controlled Ignition Angle Compensation

When the valve timing control system works, the engine's intake and exhaust overlap angle

Main ignition

angle

Water temperature

correction

Air temperature

correction

Valve plate

correction

Accelerate

correction

Idle speed
correction

Ignition angular

advance

Ignition angle

compensation of

valve timing control

Air

conditioning

correction

Power deepen

correction

Decrease fuel cut

off correction

Ignition angular

advance calculation

103

change will affect the internal exhaust gas recirculation rate and the cylinder temperature.
According to different valve timing, system needs to adjust ignition advance angle to ensure that
under current valve timing, the actual ignition advance angle can achieve the best.

F. Deceleration

Fuel

Cut-off

Adjustment

When the system exits the deceleration fuel cut-off control mode, the ignition angle will be
adjusted to make the throttle close transition smooth.

G. Air-Conditioning

Control

Adjustment

When the engine is idling, turn off the Air-Conditioner. The ignition angle will be adjusted to
make the engine run smoothly.

2.2.3.4 Electronic Throttle Body Function Restrictions

1. Forced Shut Down Mode

When ECM reports a malfunction or that the intake or throttle air flow control has a problem, the
control strategy is to stop the fuel supply and the ignition, and to close the throttle as well as to
shut down the engine.

2. Forced Idle Speed Power Management Mode

When the engine is idling, ETC system can not reliably use the throttle to control engine power. At
this point, the ETC cancels the throttle control. The throttle opening returns to the default position.
The engine power control is achieved by stopping one cylinder fuel injection and delaying the
ignition angle.

3. Forced Idle Speed Mode

When the driver's intention can not be reliably detected, such as that all pedal signals are lost, the
vehicle only maintains cooling, heating, electricity supply and lighting functions with engine
idling. If pressing the acceleration pedal, there is no response on the engine, then in this mode the
vehicle can not be driven.

4. Restricted Power Management Mode

ETC system can not use the throttle to control engine power. In this mode, the system determines
whether the engine is at idle speed or is accelerating based on the acceleration pedal signal. The
system controls engine power output by shutting down the engine, or by stopping a cylinder fuel
injection, or by delaying the ignition. The engine output fluctuation is obvious. Working a long
time in this mode would be harmful to the engine emission system. The model ensures that the
vehicle is barely enough to be driven, but difficult to control in normal traffic or climbing on a
steep slope.

5. Mode when the reliability of determining the drive intention is decreased or when the

system can not achieve high power output

When the two acceleration pedal position sensors input signals have two much difference, the
engine's output torque is limited. The engine's response to the pedal position change is much
slower. The driver may feel that the engine power output will be significantly weakened, but the
vehicle will be still able to drive in normal traffic.

104

2.2.3.5 Idle Speed Control

Idle speed air flow control is that the
engine control system maintains the
target idle speed when throttle body is
fully closed. The system maintains a
smooth transition with the throttle
body fully closed to prevent the stall.
When the engine load changes at idle
speed, system maintains a steady
engine speed.

1. Target Idle Speed Calculation

速度补偿

减速调节

基本目标怠速

实际控制目标怠速

目标怠速计算

空调补偿

电压补偿

FE02-8040b

2. Basic

Target

Idle

Speed

At different coolant temperatures, the basic target idle settings are as follows:

Water Temperature/

Atmospheric Pressure

45 55 65 75 85 95 105

-40 1350

1350

1350

1350

1350

1350

1350

-30 1350

1350

1350

1350

1350

1350

1350

-20 1350

1350

1350

1350

1350

1350

1350

-10 1350

1350

1350

1350

1350

1350

1350

0 1250

1250

1250

1250

1250

1250

1250

10 1200

1200

1200

1200

1200

1200

1200

20 1200

1200

1200

1200

1200

1200

1200

30 1150

1150

1150

1150

1150

1150

1150

40 1000

1000

1000

1000

1000

1000

1000

50

950 950 950 950 950 950 950

60

850 850 850 850 850 850 850

Fundamental

objectives idling speed

Speed

compensation

Decelerating

adjusting

Actual control target

idlingspeed

Air-conditioning

compensation

Voltage

compensation

Target idling speed

calculation

105

70

750 750 750 750 750 750 750

80

750 750 750 750 750 750 750

90

750 750 750 750 750 750 750

100

750 750 750 750 750 750 750

110

850 850 850 850 850 850 850

120

900 900 900 900 900 900 900

3. Vehicle Speed Compensation and Deceleration Adjustment

To improve the deceleration and stop driving performance, when the vehicle is driving, the target
idle speed increases by 50 rpm higher than stopping idle speed. During the deceleration and
stopping, the speed gradually decreases to the parking target idle speed.

4. Air-Conditioning

Compensation

When turning on the air-conditioner at parking, in order to compensate the power consumption,
the target idle speed rises 20 rpm at the coolant temperature < 50℃/122℉; rises 30 rpm at the
coolant temperature of 50℃/122℉; rises 40 rpm at the coolant temperature of 60℃/140℉; rises
55 rpm at the coolant temperature of 70℃/158℉; rises 70 rpm at the coolant temperature of
80℃/176℉; rises 80 rpm at the coolant temperature of 90℃/194℉; rises 100 rpm at the coolant
temperature of 100℃/212℉.

5. Voltage

Compensation

When the system voltage is lower than 12 V, and not restored in 10 s, the system will increase the
target idle speed by 300 rpm to increase the generated electricity amount. When the external
power load impacts the system, the transient voltage will fluctuate. The system will automatically
compensate for the air flow rate in order to curb the engine speed fluctuations.

2.2.3.6 Knock Control

Knock control function is used for eliminating engine knock which would occur during
combustion and optimizing power performance of engine and economical efficiency of fuel.
System can control different cylinder knocking independently.

1. Knock Control Enable Conditions

–

Engine running time is more than 2 s

–

Engine coolant temperature is more than 70℃/158 ºF

–

Engine speed is more than 600 rpm

2. Knock Control Mode

When a knocking occurs or is likely to occur, the system will quickly delay the ignition advance
angle. System basic ignition advance angle is either normal ignition advance angle or safety
ignition advance angle. Knock controlled speed is between these two.

– Homeostatic

control

When the engine is running as per normal, ECM collects and analyzes engine combustion signals
and filters knock signal through the knock sensor. Once the knock intensity is higher than the
acceptable limit, the system will rapidly delay the ignition advance angle of cylinder in which the
detonation happened, to eliminate knocking in the following combustion. The ignition advance
angle will get back to normal angle gradually.

– Transient

control

106