SAAB WIS ONLINE

Brief description

Brief description

The Denso ECD U2P engine management system is used on the new TiD V6 diesel engine.


• E - Electronic

• C - Control

• D - Diesel

• U - Unit injector

• 2 - Generation type 2

• P - Passenger car


The main task of the engine management system is to supply the correct amount of fuel at the right moment through the electronic injectors connected to the fuel rail.

Common Rail = Fuel rail .

After the ignition key is turned and the engine starts to rotate, the fuel pump will also start because it is gear driven from the crankshaft. The feed pump draws fuel from the pump and then passes it through the high-pressure pump into the fuel rail. Depending on the torque requested by the driver with the accelerator pedal acting on a potentiometer, the high-pressure pump will deliver a fuel pressure of up to 135 MPa to the fuel rail. Short fuel pipes lead from the fuel rail to each injector, which are always under pressure while the engine is running and are controlled electronically by the engine control unit.

The electrically controlled injectors have seven small nozzles that distribute the fuel very finely and evenly to provide improved combustion in the cylinder.

Under low loads, the pressure in the fuel rail is 35 MPa and increases with the load up to 135 MPa. This is governed by two fuel control valves located between the feed pump and the high-pressure pump in the fuel pump. The engine control module and power stage are located inside the car in front of the glove box.

More sensors are now connected to the engine control module in order to efficiently regulate the fuel injection and fuel quality. This means that the precise amount of fuel is injected at exactly the right moment under all driving conditions. Each injection is divided into two parts, one short pilot injection and one main injection. The fuel rail method makes it possible to inject less than one mg fuel 3-6 degrees before the main injection. This short pilot injection gives a smooth start to the ignition, which reduces the typical diesel knocking. It also reduces exhaust emissions at low speeds and high torque output.

The ECD U2P engine management system has the following advantages over older types of diesel injection systems:


• Individual fuel quantity for each cylinder.

• Lower fuel consumption

• Lower emissions.

• Quieter running engine.

• Less vibration.


ECD U2P control module (655)

The control module reads the driver's request for power (torque request) using a number of different sensors. It calculates the permitted fuel quantity in mg/combustion and together with the fuel rail and the control valves regulates the injected fuel quantity per combustion to achieve the desired torque.

The control module has internal diagnostics that can be read using the diagnostic instrument.

The control module reads the digital information from the cruise control system switches and, if the driver so desires, the engine control module will regulate the speed of the car.

Power stage, injectors (656)

The power stage ensures the opening and closing of the injectors and receives control information from the control module concerning the duration and point in time when injection is to take place.

Accelerator pedal position sensor (379)

The position sensor has two potentiometers that inform the engine control module of the driver's torque request.

Engine coolant temperature sensor, engine management system (202)

The temperature sensor informs the engine control module of the engine temperature. This information is occasionally used to provide the engine with extra fuel for cold starting. It can also protect the engine against harmful overheating as the control module limits the fuel quantity if there is a risk of overheating.

Level switch, engine oil (243)

The oil level sensor is mounted in the oil sump and informs the control module when the oil level is low. The sensor is float type, i.e. if the oil level in the oil sump gets too low, the float in the sensor will drop and close the circuit between two contacts.

Mass air flow sensor (205)

The mass air flow sensor sends a linear voltage signal concerning the air mass flow to the engine control module. The mass air flow sensor informs the engine control module of the available air mass.

Intake air temperature sensor (407)

The temperature sensor measures the temperature of the intake air. It informs the engine control module of the temperature of the intake air so that the control module can request the correct air mass for combustion (warm air requires a high volume).

Charge air pressure sensor (603)

The pressure sensor measures the pressure of the intake air and informs the engine control module of the pressure in the intake manifold.

Crankshaft position sensor (408)

The position sensor informs the engine control module of the engine speed and state of the cylinders. The engine control module corrects the injection timing if the engine is running unevenly. The sensor is of the inductive type.

Glow plug control module (596)

The control module supplies current to the glow plugs after a request from the engine control module. The glow plug control module has a self-diagnosis and sends the result by cable to the engine control module, from which any DTCs can be read.

Switch, cruise control (141)

The driver can request that the engine control module maintain a set road speed, reduce the set road speed or increase the set road speed.

Clutch switch, cruise control (133)

The switch informs the engine control module of the position of the clutch pedal. It is used to disengage cruise control.

Brake switch, cruise control (134)

The switch is used to perform a plausibility check of the brake light switch. It is used to disengage cruise control.

Brake light switch (29)

The switch informs the engine control module of the position of the brake pedal. It is used to disengage cruise control.

Main relay, engine management system (229)

The relay controls the power supply to the diesel control system.

A/C compressor relay (156)

The relay controls the engagement and disengagement of the A/C compressor after a command from the engine control module.

Control valve, charge air (179a)

The control valve governs the boost pressure using the vacuum from the vacuum pump.

EGR valve (606)

The EGR valve is a solenoid and receives an order from the engine control module to allow the passage of a certain amount of exhaust gas in order to attain the necessary air mass that the control module has calculated for combustion.

Camshaft position sensor (555)

The position sensor keeps track of the camshaft position so that the engine control module will know which cylinder is in turn for ignition. The sensor is of the inductive type.

Fuel temperature sensor (651)

The sensor is mounted in the fuel line on the engine and detects the temperature of the fuel. This information is used by the engine control module to correct the injection.

Fuel pressure valve, fuel rail (652)

There are two valves to regulate the pressure in the fuel rail depending on the pressure that is required. The valves are mounted on the rear of the fuel pump and are controlled by the engine control module, which sends them PWM signals.

Fuel pressure sensor, fuel rail (653)

The pressure sensor monitors the correct pressure in the fuel rail.

Position sensor guide rails, turbocharger (654)

The position sensor is located in the turbocharger vacuum regulator. The sensor detects how much or how little the guide rails in the turbocharger have turned, i.e. the amount of boost the turbocharger is to deliver.