Contents: ECU with 128 contacts 🠛 Maximum crankshaft speed 🠛 Camshaft phase regulator 🠛 Operating principle of signal lamps 🠛 Communication between the injection…🠛 Air conditioning compressor…🠛 Operating principle of the throttle…🠛 Throttle Body Backup Modes 🠛
Fig. 2.225. Location of injection system elements in the engine compartment of a Megane II with a K4J engine: 1 – fuel vapor recirculation electromagnetic valve; 2 – absolute pressure sensor; 3 – throttle valve unit with servo drive; 4 – ignition coil; 5 – Injection system control unit; 6 – protection and switching unit; 7 – coolant temperature sensor; 8 – knock sensor; 9 – air temperature sensor; 10 – fuel distribution rail and injectors
Fig. 2.226. Location of injection system elements in the engine compartment of a Megane II with a K4M engine: 1 – fuel vapor recirculation electromagnetic valve; 2 – electromagnetic valve of the camshaft phase regulator; 3 – absolute pressure sensor; 4 – ignition coil; 5 – camshaft position sensor; 6 – throttle valve unit with servo drive; 7 – Injection system control unit; 8 – protection and switching unit; 9 – coolant temperature sensor; 10 – knock sensor; 11 – air temperature sensor; 12 – fuel distribution rail and injectors
Fig. 2.227. Location of injection system elements in the engine compartment of a Megane II with an F4R engine: 1 – fuel vapor recirculation electromagnetic valve; 2 – electromagnetic valve of the camshaft phase regulator; 3 – absolute pressure sensor; 4 – ignition coil; 5 – throttle valve unit with servo drive; 6 – Injection system control unit; 7 – protection and switching unit; 8 – coolant temperature sensor; 9 – knock sensor; 10 – air temperature sensor; 11 – fuel distribution rail and injectors
ECU with 128 contacts
The S3000 unit from SAGEM controls the injection and ignition systems and has multi-point sequential injection (f4R, K4J engines).
There is no TDC sensor for the first cylinder piston on the camshaft, so synchronization of the control of the system elements with the engine operating process is carried out according to the program using the TDC sensor signals. The engine is started in a semi-sequential mode (to synchronize the control of system elements with the engine operating process), then switches to sequential synchronized mode.
K4M engines are equipped with a TDC sensor of the piston of the first cylinder on the camshaft. Synchronization of control of system elements with the working process of the engine (determining the TDC of the piston of the 1st cylinder) is carried out by the signal of this sensor. The engine is started in a semi-sequential mode (to synchronize the control of system elements with the engine operating process), then switches to sequential synchronized mode.
The fuel injection system malfunction indicator light on the instrument panel is on.
The use of a special warning lamp for a malfunction of the injection system (the OBD "On-Board Diagnostics System" warning lamp). Its presence is due to the installation of the "On-Board Diagnostics System".
Special precautions due to the presence of an electronic anti-theft engine immobilizer system.
Due to the installation of the third generation electronic anti-theft engine start blocking system, the ECU is replaced using a special technique.
Fuel delivery system without fuel return to the fuel tank.
The pressure regulator is located in the "fuel pump - fuel level sensor" unit.
Idle mode (hot engine).
Nominal idle speed
The idle speed is adjusted depending on:
- coolant temperature;
- battery voltage;
- air conditioner conditions (on/off);
- oil pressure (car with K4M engine);
- positions of the automatic transmission selector lever (car with F4R engine).
Maximum crankshaft speed
Protection against exceeding the maximum permissible crankshaft speed of a cold engine K4J
If the coolant temperature is below 60°C, or within 10 s after the engine has started, the fuel supply is stopped at 5800 min⁻¹.
K4M
If the coolant temperature is below 75°C, or within 10 s after the engine has started, the fuel supply is stopped at 5800 min⁻¹.
F4R
If the coolant temperature is below 75°C, or for no more than 17 seconds after the engine has started, the fuel supply is stopped at 5900 min⁻¹.
Protection against exceeding the maximum permissible crankshaft speed of a hot engine
If the engine is hot, this value takes on its normal value.
K4J and K4M
Fuel supply stops at 6500 min⁻¹ regardless of the gear engaged (manual or automatic transmission).
F4R
Fuel supply stops at 6000 min⁻¹ regardless of the gear engaged (manual transmission) and 6300 min⁻¹ (automatic transmission).
Camshaft phase regulator
K4M
The valve timing changes smoothly from 0 to 43° by the crankshaft rotation angle. The phase regulator is controlled by an electromagnetic valve, which is supplied with power in the form of a variable signal of the cyclic opening degree from the injection system ECU.
F4R
The phase regulator is an electromagnetic valve that is powered on a yes-no basis by the injection system ECU.
Control of the electric fan of the engine cooling system and the coolant temperature warning lamp
The request comes from the injection system ECU via the multiplex network (centralized coolant temperature control function). The supply voltage is supplied to the electric fan from the protection and switching unit.
Air conditioning compressor control
The request comes from the injection system ECU via the multiplex network. The request is generated based on the climate control system operation data, as well as the coolant temperature. The air conditioner compressor is powered via the protection and switching unit.
Fuel pump control
The request comes from the injection system ECU. The supply voltage is supplied to the fuel pump from the protection and switching unit.
Regulator - limiter
The speed limiter and air conditioning system are configured automatically.
Oxygen sensor
Two oxygen sensors are used, installed at the inlet and outlet of the catalytic converter.
Throttle body
Air supply and idle speed are controlled by a throttle valve with a servo drive.
Protection and switching unit
The unit supplies power to the following units:
- ignition coils;
- fuel pump;
- air conditioning compressor;
- electric fan;
- some actuators of the injection system (injectors, electromagnetic valve for purging the adsorber, etc.).
The protection and switching unit is located in the engine compartment next to the battery. The unit provides protection for the circuits of some electrical devices.
To perform this function, the unit includes fuses and several built-in relays:
- relay "+ after ignition switch";
- fuel pump relay;
- air conditioner compressor relay;
- engine Cooling Fan Relay;
- starter relay (starter traction relay control).
These relays are non-removable.
Injection system ECU
The unit constantly receives information about the electric power generated by the generator via the multiplex network. This is necessary to ensure that the electric power consumption of the car does not exceed the generator's capabilities. The main task is to ensure that the battery is charged.
Accelerator pedal
Replacing the accelerator pedal is not difficult.
The ECU takes the value read when the ignition is turned on as the reference value for the released pedal.
The sensor, made in the form of a two-track potentiometer, provides the ECU with information about the accelerator pedal position. The signal voltage from the sensor has two conductive tracks with different resistance. The first conductive track supplies a voltage (0–5 V) that is twice as high as the signal voltage from the second track (0–2.5 V). Comparing the voltage of both signals allows you to make sure that the generated signal corresponds to the current value.
Idle mode
Idle speed increases by no more than 160 min⁻¹ if the battery voltage is below 12.7 V.
In case of a present and stored fault of the absolute pressure sensor, the specified idle mode is set equal to:
- 896 min⁻¹ (k4J and K4M engines),
- 1024 min⁻¹ (f4R engine).
The S3000 injection system controls the illumination of three warning lights and the display of messages according to the severity of the detected faults in order to determine the necessary diagnostics.
The injection system ECU controls the activation of warning lights and the display of messages on the instrument panel. These warning lights come on during the engine start-up phase, as well as in the event of a fault in the injection system or engine overheating.
Commands to turn on the signal lamps are transmitted to the instrument panel via a multiplex network.
Operating principle of signal lamps
When starting the engine by pressing the "start" button
The "on-board diagnostics" indicator light comes on for approximately 3 seconds and then goes out.
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In case of injection system malfunction (1st degree of severity)
A written message is displayed "injection a controle" (check the injection system), accompanied by the "service" indicator lamp turning on. This indicates a decrease in the safety level and the need to use the engine in a "gentle" mode. The owner must eliminate the faults as soon as possible.
The causes of these malfunctions may be:
- throttle body with servo drive malfunction;
- accelerator pedal position sensor malfunction;
- absolute pressure sensor malfunction;
- eCU malfunction;
- faults in the power supply circuits of actuators;
- malfunctions in the ECU power supply circuit.
In case of serious malfunction of the injection system (2nd degree of severity)
A red symbol with an image of an engine and the message "stop" are displayed (only on matrix display), and a written message appears "mjection defaillante" (injection system is faulty), accompanied by the lighting of the "stop" signal lamp and an audible signal.
When the engine overheats
Engine temperature alarm symbol appears (only on matrix display) with a written message "surchauffe moteur" (engine overheating), accompanied by the "stop" signal lamp lighting up and an audible signal. In this case, you should stop driving immediately.
If a malfunction is detected that results in exhaust gas toxicity standards being exceeded
The "on-board diagnostics system" warning light with an engine symbol comes on:
- "flashing light" in case of a malfunction that could lead to destruction of the catalytic converter (misfires of the mixture leading to its destruction). In this case, you should stop moving immediately.
- "constant light" in case of exceeding the toxicity standards of exhaust gases (in case of misfires of the mixture, leading to increased toxicity, malfunction of the catalytic converter, malfunction of the oxygen sensors, inconsistency between the signals of the oxygen sensors and malfunction of the adsorber).
Communication between the injection system ECU and the air conditioning ECU
The climate control system is controlled by several ECUs.
The functions of the injection system ECU include:
- control of cooling capacity based on requests from the cabin and the pressure value in the circuit;
- determining the power consumed by the air conditioner compressor based on the pressure value in the circuit;
- issuing permissions to control the electric fan of the engine cooling system depending on the vehicle speed and the pressure in the circuit;
- issuing permission and prohibition to turn on the compressor.
When you turn on the air conditioner, the air conditioning control panel requests permission to turn on the air conditioning compressor.
The injection system ECU allows or does not allow:
- operation of the air conditioning compressor;
- operation of the electric fan of the engine cooling system;
- engine transition to idle speed.
Control commands for switching on the electric fan of the engine cooling system and the compressor come from the injection system ECU via the multiplex network. The commands are generated based on information about the operation of the air conditioning system, as well as taking into account the temperature of the coolant and the speed of the car.
The power supply voltage is supplied to the electric fan and compressor from the protection and switching unit.
The information used by the air conditioning control unit is transmitted via a multiplex network:
- contact 4 AA - multiplex network line "CAN HIGH";
- contact 3 AA - multiplex network line "CAN LOW".
The injection system ECU receives information from the refrigerant pressure sensor via the contacts:
- in J3 signal of refrigerant pressure sensor;
- in J2 "+" 5V power supply of the refrigerant pressure sensor;
- in K2 "ground" of the refrigerant pressure sensor.
Air conditioning compressor activation algorithm
During certain periods of operation, the injection system ECU prohibits the operation of the air conditioning compressor.
Algorithm for maintaining the dynamic characteristics of the engine when starting off on an incline.
To make it easier to start the car on an incline, the operation of the air conditioning compressor is prohibited for 20 seconds.
Algorithm for protection against exceeding the maximum permissible engine crankshaft speed.
The air conditioner compressor stops in the following cases:
- instantaneous crankshaft speed exceeds 6300 min⁻¹;
- the continuous crankshaft speed exceeds 5760 min⁻¹ for more than 10 s.
Overheating protection algorithm.
The compressor does not operate if the coolant temperature is above 115°C at high crankshaft speed and high engine load.
Switch-on conditions: at engine speeds above 4512 min⁻¹ and intake manifold pressure below 700 mbar.
Switch-off conditions: after a time delay of 10 s, the centralized control function of the coolant temperature is implemented.
Operating principle of the throttle valve unit
The throttle valve unit regulates idle speed and changes the amount of air entering the engine. The unit consists of an electric motor and a potentiometric throttle valve position sensor with two conductive tracks.
At idle, the throttle position is set depending on the set idle speed, which depends on the number of high-power electrical consumers turned on (air conditioner) and engine operating conditions (air and coolant temperatures).
When you press the accelerator pedal, the throttle valve opens to the corresponding angle.
However, in order to improve driving comfort, the throttle opening is not directly proportional to the driver's control input.
To eliminate jerking, facilitate gear shifting and ensure safety, the throttle valve unit allows you to vary the engine torque.
Throttle Body Backup Modes
There are four throttle body backup modes.
1. Dynamic performance limitation mode.
This mode is used in case of faults in electrical circuits for which there is a safe solution suitable for the injection system (malfunction of one of the two conductive tracks of the accelerator pedal position sensor or throttle valve unit). In this mode, acceleration characteristics and maximum throttle opening are limited (maximum speed is 90 km/h for cars with a manual transmission and 100 km/h for cars with an automatic transmission).
2. Mode of loss of driver control.
This mode is also called "electric standby position". This mode is used in the complete absence of information about the accelerator pedal position, but the injection system ECU continues to control the filling of the engine cylinders with air (the throttle actuator remains controllable). In this mode, the injection system ECU sets the specified accelerator pedal positions for each gear and switches the engine to idle speed when the brake pedal is pressed. In this case, the maximum crankshaft speed with the gearbox in neutral is limited to 2500 min⁻¹.
3. Backup mechanical position mode.
This mode is used in case of malfunctions that lead to loss of throttle control (the damper actuator does not work). In this case, the throttle valve is in the mechanical rest position, the injection system ECU limits the crankshaft speed by stopping the injection and the torque by disabling the cylinders (ignition and injection stop) depending on the accelerator pedal position. As a result, the maximum crankshaft speed in full load mode or with the gearbox in neutral remains equal to 2500 min⁻¹.
4. Pedal position tracking mode.
In the event of loss of manifold pressure information, the degree of throttle valve opening is directly proportional to the position of the accelerator pedal.
Note: When switching to any of these modes, the fuel injection system malfunction indicator lamp lights up on the instrument panel.
Correction of idle speed depending on coolant temperature (f4R engine)
* Except when starting the engine at a temperature of 15–30°C.
Correction of idle speed depending on coolant temperature (k4J engine)
* Except when starting the engine at a temperature of 15–30°C.
Correction of idle speed depending on coolant temperature (k4M engine)
* Except when starting the engine at a temperature of 15–30°C.
Correction of idle speed depending on battery voltage and electrical energy balance
The engine idle speed correction compensates for the voltage drop when the power consumer is turned on if the battery is weakly charged. The correction starts when the voltage drops below 12.7 V. As a result of the correction, the engine speed can be increased by no more than 160 min⁻¹, i.e. up to 910 min⁻¹.
Correction of idle speed in case of absolute pressure sensor failure
If the absolute pressure sensor is faulty, the idle speed of the crankshaft increases to 1024 min⁻¹.
If the engine is started at a coolant temperature of 15–30°C and then left in idle mode, a gradual decrease in crankshaft speed may occur. This is due to the presence of a function to reduce toxicity of exhaust gases when the engine is started (switching on the heating elements of the oxygen sensors).