XC90 AWD V8-4.4L VIN 85 B8444S (2005)
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 manifold absolute pressure (MAP) sensor intake is located on the upper rear edge of the engine (passenger compartment side).
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 to the control module. Low pressure
results in low voltage, high pressure gives high voltage.
The pressure sensor can be diagnosed by the engine control module (ECM) and the sensor signal can be read off.
Fuel pressure sensor/fuel temperature sensor
The fuel pressure and fuel temperature sensors are combined.
The sensor detects the fuel pressure (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.
The fuel pressure/fuel temperature sensor can be diagnosed by the engine control module (ECM) and its signals (pressure and temperature) can be read
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 to the engine control module (ECM). Low pressure results in low voltage, high pressure gives 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,
B8444S See: Powertrain Management/Computers and Control Systems/Description and Operation/Engine Control Module (ECM)/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.
Note! The absolute pressure is displayed when using parameter read outs 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