2.2.2 Description and Operation 

2.2.2.1 Overview 

This engine control system uses Delphi MT22.1 Control System. Its main characteristic is that the 
engine control module (ECM) acts as the core system. The traditional mechanical throttle pedal 
and mechanical throttle body are replaced by more advanced electronic throttle acceleration pedal 
sensor assembly and the electronic throttle body assembly. Due to this advanced system, ECM 
torque control over the engine is more convenient. In addition, MT22.1 control system also 
incorporates multi-point sequential fuel injection, group direct ignition without electricity 
distributions, variable valve timing control and three-way catalytic converter post-processing, 
capable to meet the increasingly stringent emission regulations. 

The system’s main functions include: 

1.  Engine torque output control mode: ECM calculates the gas flow through the intake air 

temperature sensor and intake manifold pressure sensor signals, making the Air-Fuel ratio 
closer to the current engine’s operating condition demand. 

2.  Torque control mode: ECM calculates the current required output torque and controls the 

engine output power, according to the acceleration pedal position sensor signal. 

3.  Main relay control of Complete Vehicle. 

4.  Close-loop control multi-point sequential fuel injection: A close-loop fuel control can 

precisely control the engine air- fuel ratio, and therefore efficiently controls emissions. Close- 
loop control can effectively eliminate the system and related mechanical component swear 
and tear due to manufacturing error and improves vehicle consistency. 

5.  Variable Valve Timing (VVT) control: Variable valve timing control system uses VVT 

actuator to change the relative positions between intake camshaft and crankshaft. Engine 
management system calculates the best valve timing based on engine operating conditions, 
and controls VVT solenoid valve movement, allowing flow and direction of oil pressure in 
VVT actuator to change, and ultimately promoting the camshaft movement to the desired 
position. 

6.  Fuel supply control without fuel return. 

7.  Fuel pump working control. 

8.  ECM has built-in ignition drive module and group direct ignition without electricity 

distributions. 

9.  Knock Control: When the knock sensor detects a knock occurring, the system will calculate 

the ignition advance angle delay based on the current conditions, knock intensity and other 
necessary information, and defers the ignition advance angle, so as to avoid or reduce knock. 
Electronic Throttle Control: Since the system uses an electronic throttle, highly precise idle 
control can be achieved. Taking the electrical load compensation as an example, when there 
is electrical load or the load is cut off, due to the sudden increase or decrease in engine load 
which results in engine speed fluctuation in a certain range, therefore, we add the electrical 
load control adjustments. When the load increases or decreases, adjust the air flow rate and 
/or the ignition advance angle accordingly to make sure that the idle speed remains steady at 
the best condition. 

10.  Canister Solenoid Valve Control 

11.  Cooling fan relay control 

12.  System self-diagnostic function: After the system enters working condition, ECM controls all 

system components working, and tests them in real time. Once the system or component 
malfunction occurs, the system will light up the engine malfunction lamp to remind the driver 
to repair or service the vehicle on time. In the mean time, ECM will start fault protection 
mode. 

13.  System over-voltage protection: When the charging system malfunction causes the voltage 

95

too high, the system will enter protection mode to restrict the engine speed to prevent ECM 
damage. 

2.2.2.2 Components Description 

1.  Engine Control Module (ECM) 

Engine control module is a microprocessor with a single chip as the core. Its function is to process 
data from various vehicle sensors to determine the engine's working condition, and controls each 
engine actuator through various actuators. 

ECM Normal work voltage is 9.0 V–16 V 

Notes: 

Although ECM has the over-voltage and reverse polarity voltage protection function, during the 
repair process it is prohibited to connect the battery positive and negative wrong or apply voltage 
higher than 15 V. Otherwise, it will cause damage to ECM and other electrical equipments. 

2.  Crankshaft Position Sensor 

The crankshaft position sensor output can be used to determine crankshaft position and rotation 
speed. The engine rotation speed and crankshaft position sensor are magnetic-electric sensors 
installed near the crankshaft. When the crankshaft rotates, they work together with the 58X gear 
on the crankshaft. The 58x tooth top and the alveolar pass through the sensor in different distances 
when the crankshaft rotates. The sensor senses the reluctance change; the alternating reluctance 
generates an alternating output signal. The 58x gear plate gap position aligns with engine top dead 
center. When the cylinder No.1 reaches top dead center, the sensor aligns with the 20th tooth lower 
edge. ECM uses this signal to determine crankshaft position and rotation speed. 

Resistance Value of the Sensor: 20-30℃（68-86℉）900-1100Ω. 

Output Voltage: 400 mV at 60 rpm, the voltage increases as the speed increases. 

3.  Intake Air Pressure/Temperature Sensor: 

This sensor detects intake manifold pressure change caused by engine load and speed changes. 
These changes will be converted to the voltage output. When the engine decelerates, the throttle 
body closes to result in a relatively low intake manifold absolute pressure output. Intake manifold 
absolute pressure and vacuum degree is opposite. When the manifold pressure is high, the vacuum 
degree is low. MAP sensor is also used to measure atmospheric pressure. This measurement is 
completed as part of the MAP sensor calculation. When the ignition switch is turned on and the 
engine is not running, the engine control module reads the intake manifold pressure as 
atmospheric pressure, and adjusts the Air-Fuel ratio accordingly. With this kind of altitude 
compensation, the system can maintain a low emission while maintaining maneuverability. 

4.  Camshaft Position Sensor (CMP) 

Camshaft position sensor is a Hall-effect sensor which is installed in the vicinity of the intake 
camshaft, and works together with camshaft signal wheel. The signal wheel is corresponding to 
the specific engine position. ECM measures digital voltage signal through this sensor, therefore 
determining the working cylinder of the engine and implementing one-to-one control. Engine 
control module then calculates the actual sequence of fuel injection. If the engine is running when 
the camshaft position sensor signal is lost, the fuel injection system will be converted to the 
sequential fuel injection mode based on the final fuel injection pulse, while the engine continues to 
run. If the engine starts after being shut down, the fuel injection sequence will be converted from 
sequential injection to group injection. Even if the fault exists, the engine can be restarted. 

5.  Engine Coolant Temperature (ECT) Sensor 

Engine coolant temperature (ECT) sensor is used to detect the engine operating temperature. ECM 
provides the best control scheme depending on the temperature. The sensor uses a negative 
temperature coefficient thermostat as the sensing element, when the coolant temperature rises, the 
resistance decreases. At -30°C the resistance is 52,594 Ω; at 130 °C, the resistance is 77.5 Ω. The 
sensors are installed in the main coolant path. The coolant temperature signal is important to the 

96

ignition timing and fuel injection adjustment, while the signal is also transmitted to the instrument 
panel (IP) and used to display the current engine working temperature. 

6.  Knock Sensor (KS) 

Knock sensor is a frequency response sensor, installed at the engine block’s most sensitive part to 
knocking under the intake manifold. ECM uses knock sensor to detect knock intensity, so as to 
adjust the ignition advance angle to effectively control knocking and optimize the engine power, 
fuel economy and emission levels. If the engine knocking occurs, ECM will receive this signal, 
filter out the non-knock signals and make the calculation. It determines the engine’s position in the 
working cycle through the camshaft and crankshaft position sensor signals, according to which the 
ECM figures out the knocking cylinder and then delays the ignition advance angle for this cylinder 
until the knocking disappears. Then ECM advances the ignition advance angle until the ignition 
angle is best suited for the operating conditions at that time. Due to weak sensor signals, the sensor 
lead has a shielded cable. Its resistance is over 1M Ω (20-30℃) with the output signal greater than 
17 mV/g in any case. 

7. Oxygen 

Sensor 

Oxygen sensor is an important symbolic component in a close-loop fuel control system, which 
adjusts and maintains the ideal Air-Fuel ratio, so that three-way catalytic converter achieves the 
best conversion efficiency. When the Air-Fuel ratio for engine burning becomes thin, the oxygen 
content in the exhaust increases, and oxygen sensor output voltage is reduced. On the contrary, the 
output voltage increases to feedback the air- fuel ratio to ECM. 

Oxygen sensor sensing material is Zirconia, hollow with an external sensing part. When the 
Zirconia components are heated (>300℃) for activation, the reference air enters the hollow part of 
the Zirconia component through the lead wire. The exhaust passes through the outer electrode, and 
the oxygen ions move from the center of the zirconia to the outer electrode, which thus consists of 
a simple atomic battery with a voltage between two electrodes; the Zirconia can alternate the 
output voltage according to the oxygen concentration in the exhaust and therefore determine the 
oxygen content of exhaust gas. Usually, the oxygen sensor is designed to generate a voltage 
amplitude jump in the vicinity of the exhaust theoretical Air-Fuel ratio of (14.7:1) to help the ECM 
determine the Air-Fuel ratio accurately. 

8. Fuel 

Injectors 

The injector nozzle’s structure is an electromagnetic switch ball valve device. The both electrodes 
from the coil are connected to the ECM and the power supply through the engine wiring harnesses. 
When the coil is controlled by ECM to connect to the system ground, the resulting magnetic force 
overcomes the spring force, fuel pressure and manifold vacuum suction to draw up the valve core. 
The fuel sprays from the guide hole through the valve seat hole    mistily to the intake valve. When 
the power supply is cut off, the magnetic force disappears. Under the spring force and the fuel 
pressure, the injector nozzle closes. The top of the fuel injector has the reliable fuel pressure 
sealing generated by the rubber seal ring and the fuel rail interface; the lower part also uses the 
rubber seal ring and engine air intake manifold to form the air sealing. Fuel injector resistance is 
11.4-12.6 Ω. 

Note: When the fuel injector is blocked or not closed tightly, the engine malfunction lamp may 
be lit, but the detection fault code is: oxygen sensor distortion, erratic signal, abnormal Air-Fuel 
ratio and other faults. At this time, the failure component should be carefully judged. Because 
when the fuel injector is blocked or leaking, the amount of fuel injected is not controlled by the 
ECM pulse width, the mixed air concentration signals of the oxygen sensor feedback to ECM 
will be very different from the ECM control target. When ECM detects this signal, it will 
determine whether the oxygen sensor is working properly. But the system cannot determine 
whether the fault comes from the oxygen sensor itself or other associated malfunction due to the 
damage of other parts. Therefore, at the service of such malfunctions, the failed components 
must be carefully identified. 

9. Fuel 

Pump 

Assembly 

The fuel pump is turbine single-stage electric fuel pump under the control of the ECM via the fuel 

97

pump relay. It has a check valve at the outlet of the fuel pump. When the engine is not running, the 
remaining oil in the pipeline will not quickly return to the fuel tank, so as to ensure the re-starting 
performance. Fuel level sensor is a variable sliding resistance type. 

10. Ignition Coil 

Cylinder 1 and 4 have their ignition coils located at the top of the Cylinder 4’s spark plug opening. 
Cylinder 2 and 3 have their ignition coils located at the top of the Cylinder 2’s spark plug opening. 
Ignition coil primary winding low voltage will be transformed into the secondary winding high 
voltage. The spark plug discharges spark, igniting the air and fuel mixture inside the cylinder. 
Ignition occurs when one piston is at the compression TDC and the other is at exhaust TDC. For 
the internal air pressure in the cylinder near the exhaust TDC is low but the temperature is high. 
Less energy will enable the ignition through electrode puncture at the spark plug with less energy, 
known as redundant ignition. While, the cylinder mixture density and pressure is high at the 
compression TDC, more ignition energy is required for spark plug ignition making the mixture 
quickly ignited for power. Therefore, this cylinder ignition is called the effective ignition. 

11. Electronic 

Throttle 

Body 

(ETC) 

The electronic throttle valve assembly opening is determined by ECM according to the 
driver-controlled throttle pedal control input signals, and other input signals after calculating the 
vehicle currently needed engine output power to control the fuel supply (spray) amount, and then 
adjusting the control parameters based on feedback signals to make sure that the engine works 
under the best controlled status. Electronic throttle valve body adds the drive motor, gear drive 
mechanism and other components, as well as a throttle position sensor with enhanced functionality 
and reliability. 

12.  Canister Solenoid Valve (EVAP) 

The canister control valve is located at the side of the engine cylinder head (transmission side) and 
is used to control the canister purge flow. ECM controls intake manifold gasoline vapor volume 
through canister solenoid valve. ECM sends square pulse wave. Air flow volume and control pulse 
square wave relationship is linear. 

ECM changes canister working time and rate according to engine speed and load conditions. 

Solenoid valve coil resistance: 11 - 22 Ω. 

13.  Variable Valve Timing Solenoid Valve (VVT) 

VVT solenoid valve is located at the intake manifold side near the engine front. VVT magnetic 
valve is a 4-digit 4-channel solenoid valve with the working power supplied from main relay 
controlled by ECM. ECM controls VVT solenoid valve grounding with a pulse width modulation 
signal. The crankshaft to the camshaft timing relations can be continuously changed. The best 
valve timing control can be achieved at different engine running conditions. This will help to 
increase engine efficiency, improve idle stability, and provide more torque and power, while 
helping to improve the fuel economy and lower emissions of hydrocarbons and nitrogen oxides. 

Solenoid valve resistance: 7.2 Ω at 20°C (68℉) 

98