The engine of T21 model adopts UAES engine management system. This system mainly consists engine
Control Module (ECM), sensors and actuators, which controls intake air amount, injection volume and ignition
timing, etc. when engine is operating.
In engine management system, sensors are used as the input part to measure various physical signals
(temperature and pressure, etc.), and converts them into corresponding electrical signals; the function of ECM
is to receive the input signals from sensors and perform calculation according to set procedure, producing
corresponding control signals and outputting them to power drive circuit. The power drive circuit drives each
actuator to perform various actions, thus making the engine run according to preset program.
Also, the trouble diagnosis system of ECM monitors each component and control function in this system.
Once detecting and confirming a fault, it will store trouble code and recall "Limp Home" function. When
detecting that fault has been eliminated, it will return to use normal value.

Basic Components of Engine Management System

RT21060010

06–

System Function

 Calculate air flow

ECM calculates air flow by the signals from air flow meter and then adjusts injection volume to make air-
fuel ratio meet the requirements of various operating conditions.

 Measure crankshaft position and engine speed

ECM determines crankshaft position and engine speed according to the signals from crankshaft position
sensor and accurately controls engine ignition and injection timing.

 Determine operating sequence of cylinders

ECM recognizes the top dead center of No.1 cylinder by camshaft position sensor, so as to determine the
operating sequence of cylinders.

 Fuel control

There are two modes of fuel control: closed-loop fuel control and open-loop fuel control. The closed-loop
fuel control can accurately regulate the air-fuel ratio of engine, thus effectively controlling emissions. The
open-loop fuel control is applied when engine is starting or warming up, or when a oxygen sensor is
malfunctioning.

 Ignition control

The ignition control system of engine adopts packet control.

 Knock control

When a knocking is detected by knock sensor, the system will calculate the ignition advance angle that
needs to be delayed or advanced according to current operating conditions and knock intensity and
adjusts ignition angle, thus avoiding or reducing knocking.

 Emission control

The three-way catalytic converter can convert engine exhaust gas into harmless gas and discharge it into
atmosphere. When engine temperature becomes normal after warming up, ECM will activate closed-loop
fuel control to correct air-fuel ratio, thus realizing the optimum conversion efficiency of three-way catalytic
converter.

 Three-way catalytic converter protection

The engine management system has the function to protect three-way catalytic converter. The ECM
estimates three-way catalytic converter temperature according to engine operating conditions. When it is
estimated that exhaust temperature will exceed the converter's maximum permissible temperature for a
long time, ECM will automatically activate the protection function of three-way catalytic converter to keep
the temperature normal.

 System voltage protection

When system voltage becomes extremely high due to charging system malfunction, engine management
system will activate the protection program to limit engine speed, thus avoiding damage to ECM and
battery.

1 - Canister

2 - Air Flow Meter

3 - Canister Solenoid Valve

4 - Intake VVT Control Valve

5 - Camshaft Position Sensor (Intake)

6 - Ignition Coil

7 - Camshaft Position Sensor (Exhaust)

8 - Fuel Injector

9 - Exhaust VVT Control Valve

10 - Upstream Oxygen Sensor

11 - Downstream Oxygen Sensor

12 - Coolant Temperature Sensor

13 - Crankshaft Position Sensor

14 - Knock Sensor

15 - Electronic Throttle

16 - Engine Control Module (ECM)

17 - Electronic Accelerator Pedal

18 - Electric Fuel Pump

06–

Precautions

General service requirements
 Only digital multimeter can be used to perform inspection for engine management system.
 Use genuine components to perform service work, otherwise, the appropriate engine management system

operation cannot be guaranteed.

 Only use unleaded gasoline during servicing.
 Please observe normative service and diagnostic flowchart to perform service work.
 Never disassemble the components of engine management system during servicing.
 When holding electronic elements (ECM, sensor, etc.) during servicing, take extra care not to drop them on

the ground.

 Set up a consciousness of environmental protection and dispose of the waste effectively that is produced

during servicing.

Precautions during servicing
1. Do not causally remove any component or its connector of engine management system from its installation

position to prevent damage accidentally, or foreign matter, such as moisture, oil from entering connectors,
which will affect the normal operation of engine management system.

2. Be sure to turn ignition switch off when disconnecting and connecting connectors. Otherwise, electric

elements may be damaged.

3. When simulating hot operating condition of malfunction and performing other service work that may cause

the temperature to rise, never allow ECM temperature to exceed 80°C.

4. As the supplying pressure of fuel system is high (approximately 400 kPa), all the fuel pipes are high

pressure resistant pipe. The fuel pressure in fuel lines is still high even when engine is not running.
Therefore, be careful not to casually remove the fuel pipe during servicing; when it is necessary to service
the fuel system, discharge the pressure in fuel system before removing fuel pipe. The way to discharge
pressure is as follows:
Remove fuel pump relay, start the engine and idle it until the engine stops running by itself. Then attempt to
start the engine 2 - 3 times to ensure fuel pressure is discharged completely. The removal of fuel pipe and
replacement of fuel filter should be performed in a well-ventilated area by professional service men.

5. Do not energize electric fuel pump when removing it from fuel tank to prevent electric sparks, which will

cause a fire.

6. Running test for fuel pump is prohibited when it is empty or in water; otherwise, it will shorten the service

life. Never connect the positive and negative of fuel pump in reverse.

7. When checking ignition system, only perform spark jump test when it is necessary and the time should be

shortened as much as possible. Do not open throttle during test; otherwise, a large amount of unburned
gasoline will enter the exhaust pipe, causing damage to three-way catalytic converter.

8. As idling adjustment is performed by engine management system completely, manual adjustment is not

required. The accelerator pedal stopper screw of throttle body has been adjusted at the factory, and the
user is not allowed to change its original position.

9. Do not connect battery with its polarity reversed to prevent damage to electronic elements. This system

adopts negative ground.

10.Never remove battery cable when engine is running.
11.The positive, negative battery cables and ECM must be removed before performing welding on vehicle.
12.Do not puncture wire outer coat to detect electric signals input and output by components.

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