Design [3 of 4]

Manifold absolute pressure (MAP) sensor




The manifold absolute pressure (MAP) sensor is on top of the radiator and is connected to the intake manifold by a hose.
The manifold absolute pressure (MAP) sensor detects quick pressure changes in the intake manifold after the throttle. The signal from the sensor is used by the engine control module (ECM) to supplement the mass air flow (MAF) sensor when calculating injection period.
The semi-conductor sensor is grounded in the control module and is supplied with power from the control module.
The resistance in the intake manifold moves the silicone membrane in the sensor, giving a signal of 0.5 - 4.5 V. Low pressure results in low voltage, high pressure in high voltage.
The engine control module (ECM) can diagnose the manifold absolute pressure (MAP) sensor. The sensor signal can be read using VIDA.

Leak diagnostic unit (certain markets only)




The function of the leak diagnostic unit is to pressurize the fuel tank system during leak diagnostics.
The leak diagnostic unit consists of a plastic housing with:
1. electrical air pump
2. a valve / solenoid which governs the air flow in the unit
3. a heater element (PTC resistor) which warms up the pump.
The electrical pump, valve and heater element in the unit are supplied with voltage by the system relay. The pump, valve and heater element are grounded (control) in the engine control module (ECM).
When leak diagnostics are not active, the valve is held open to ambient air for EVAP control to be carried out.
During leak diagnostics the pump in the leak diagnostic unit starts. The valve in the unit is operated by the engine control module (ECM) by grounding the different circuits internally in the engine control module (ECM).
The Engine control module (ECM) checks the fuel tanks system for leaks by pressurizing the system and at the same time monitoring a number of relevant parameters. Also see: Leak diagnostics (certain markets only) Leak Diagnostics (Certain Markets Only)
The engine control module (ECM) can diagnose the leak diagnostic unit.
The valve in the leak diagnostic unit can be activated.
The leak diagnostic unit is at the upper front edge of the fuel tank.

Engine speed (RPM) sensor




The engine speed (RPM) sensor provides the Engine Control Module (ECM) with information about the speed and position of the crankshaft. The Engine Control Module (ECM) is able to use the signal from the engine speed (RPM) sensor to determine when a piston is approaching top dead center (TDC). However it is unable to use the signal from the engine speed (RPM) sensor to determine whether the piston is in the combustion stroke or whether the exhaust valve is open (exhaust stroke). The signal from the camshaft position (CMP) sensor is also required to determine the operating cycle of the engine. See also: Camshaft position (CMP) sensor
The signal from the engine speed (RPM) sensor is also used to check the engine for misfires. For more information, see: Misfire diagnostic Misfire Diagnostics
There is a steel ring with stamped holes welded to the rim of the primary section (the section fixed to the crankshaft) of the flywheel.
The holes are positioned with a gap of 6° between each hole. This arrangement creates a hole for each tooth. There are 360° in one revolution. 6° between each hole means that there are 60 holes. However two holes are not stamped, to create a reference position (long gap - missing tooth) for the crankshaft. The first tooth after the reference position is located 84° before TDC on cylinder 1. See: Function, B5244S4 Function
The engine speed (RPM) sensor is at the rear of the engine above the flywheel.
The sensor is inductive with a permanent magnet. An alternating current is induced in the sensor when the flywheel/carrier plate passes the engine speed (RPM) sensor. The generated voltage and frequency increases with the engine speed (rpm).
The signal varies between 0.1-100 V depending on the engine speed (RPM).
The Engine Control Module (ECM) is able to determine the engine speed (RPM) by counting the number of holes per time unit. When the reference position passes the engine speed (RPM) sensor, the voltage and frequency drop momentarily to zero, even though the engine is still running. This allows the engine control module (ECM) to determine the position of the crankshaft.
If the signal from the engine speed (RPM) sensor is incorrect or missing, the control module will use signals from the camshaft position (CMP) sensor.
The engine control module (ECM) can diagnose the engine speed (RPM) sensor. The sensor value (engine speed (rpm)) can be read off using VIDA.

Fuel pressure sensor / fuel temperature sensor





Overview
The fuel pressure sensor is combined and consisted of both the fuel pressure sensor and the fuel temperature sensor. The sensor detects the fuel pressure (the absolute pressure) and the temperature of the fuel in the fuel rail.
The fuel pressure sensor is on the right-hand end of the fuel rail.

Fuel pressure sensor
The pressure sensor is a piezo resistive type resistor, the resistance of which changes with the pressure. Depending on the pressure in the fuel rail, an analog signal of 0-5 V is transmitted. Low pressure results in low voltage, high pressure in high voltage.
The engine control module (ECM) then uses this signal to adjust the pressure in the fuel rail using the fuel pump control module. See also: Function, B5244S4 Function
The pressure sensor is supplied with 5 V and grounded in the engine control module (ECM). The pressure sensor transmits a signal indicating the fuel pressure to the engine control module (ECM) on a separate cable.
The engine control module (ECM) can diagnose the fuel pressure sensor. Its signals (pressure and temperature) can be read using VIDA.

Note! The absolute pressure is displayed when using VIDA parameter readout to read off the fuel pressure. If there is no pressure at the fuel rail, the atmospheric pressure will be displayed.

Hint: The relative pressure (absolute pressure minus atmospheric pressure) is displayed when reading off the fuel pressure via a manometer connected to the fuel rail.

Fuel temperature sensor
The temperature sensor is an NTC sensor. The sensor is supplied with voltage (signal) from and grounded in the engine control module (ECM).
The resistance in the sensor changes according to the temperature of the fuel. This provides the engine control module (ECM) with a signal of between 0-5 V. Low temperature results in high voltage (high resistance). High temperature results in low voltage (low resistance).
The engine control module (ECM) uses the signal to calculate the density of the fuel.

Camshaft position (CMP) sensor




The function of the camshaft position (CMP) sensor is to detect the position of the camshaft rotor flanks. The signal from the sensor is used by the engine control module (ECM) to determine cam timing.
Each camshaft has five flanks per camshaft revolution. Camshaft position sensor (CMP) uses a pulse wheel on the camshaft consisting of five teeth (one tooth positioned by each flank) to detect the flanks.
The flanks are not symmetric on the camshaft. This allows the control module to determine which flank has been detected and therefore which operating cycle the camshaft is in.
When the operating cycle of the camshaft is established, the control module is able to determine which cylinder should be ignited. In the event of misfire or engine knock, the control module is also able to determine which cylinder is misfiring or knocking. See also: Knock sensor (KS) and Engine speed (RPM) sensor.
Data about the position of the camshaft is used during camshaft control (CVVT). See also: Function, B5244S4 Function
The sensor, which is a magnetic resistor with a permanent magnet, is grounded in the control module and supplied with 5 V from the control module. When one of the teeth on the camshaft pulse wheel passes the camshaft position (CMP) sensor, a signal is transmitted to the control module from the camshaft position (CMP) sensor. The signal varies between 0-5 V and is high when a tooth is in contact with the camshaft position (CMP) sensor and low when the tooth leaves the camshaft position (CMP) sensor.
Both the intake camshaft and exhaust camshaft have a camshaft position sensor. Cylinder detection on start up (the operating cycle of each cylinder) is improved by using a camshaft position sensor on the intake camshaft and exhaust camshaft.
The camshaft position (CMP) sensors are located by the camshafts at the rear of the engine.
The engine control module (ECM) can diagnose the camshaft position (CMP) sensors.

Knock sensor (KS)




The function of the knock sensor (KS) is to monitor combustion knocking from the engine. Knocking may damage the engine and reduces the efficiency of engine combustion.
If the engine control module (ECM) registers knocking from any of the cylinders, the ignition will be retarded for that cylinder at the next combustion stage. If repeated ignition retardation does not prevent knocking, the injection period will be increased. This has a cooling effect.
The sensor is made up of a Piezo electrical crystal. If there is engine knock, vibrations (sound waves) spread through the cylinder block to the knock sensor (KS). The resulting mechanical stress in the piezo electrical material in the knock sensors generates a voltage. This signal is transmitted to the engine control module (ECM). The signal corresponds to the frequency and amplitude of the sound waves. This allows the Engine Control Module (ECM) to determine if the engine is knocking. The camshaft position (CMP) sensor and engine speed (RPM) sensor are used to determine the operating cycle of the engine (which cylinder is igniting) and therefore which cylinder is knocking.
The knock sensor (KS) is positioned on the cylinder block below the intake manifold.
The engine control module (ECM) can diagnose the knock sensor (KS).

Electronic throttle unit




The electronic throttle unit, using the control signal from the engine control module (ECM), regulates the amount of air for engine combustion. This is done using an electronic shutter.
The electronic throttle unit consists of a round throttle disc on a shaft. This is turned using a DC motor (damper motor), gear wheel and two springs, an opening spring and a return spring. The damper motor is controlled by the control module and is supplied with powered by a built in power stage in the control module. At one of the limit positions the throttle disc is closed so that no air can pass the throttle unit. At the other limit position the throttle disc is parallel to the air flow so that the air is able to freely pass through the throttle unit. The throttle spindle is electronically monitored by two throttle position (TP) sensors (Hall sensors) which are supplied with power by the control module. The signals from the throttle position (TP) sensors provide the control module with data about the position of the throttle disc. The throttle unit also has a connector with six pins.
The electronic throttle unit is located on the engine intake manifold. In the event of a fault, the throttle unit must be replaced as a single unit.
The engine control module (ECM) can diagnose the electronic throttle unit.