Intake Air Pressure and Intake Air Temperature
Sensor
Application: To measure the absolute pressure of
intake manifold (Approximate 0.1 bar) and the
temperature of intake airflow to provide the load
information to the engine, which can automatically
check the elevation depending on the volume
effects.
Structure and Working Principle: This sensor is
comprised of two sensors, namely is the
combination of the intake manifold absolute
pressure sensor and the air intake temperature
sensor, which is assembled on the intake manifold.
Intake manifold absolute pressure/air intake
temperature sensor
Intake Air Pressure Sensor is secured on the air
intake pipe directly by means of one bolt and uses
two sealing rings to prevent the leakage. This
scheme can omit the connection hose between the
intake pressure sensor and the air intake pipe and
also bear good response against the fluctuated air
pressure. The pressure sensor judges the elevation
depending on the air intake efficiency of the engine
(Dynamic air pressure correction).
Air Intake Temperature Sensor is one negative
temperature coefficient thermistor (NTC), of which
the resistance may reduce following the temperature
increasing. The system supplies the sensor with one
5V reference voltage and the ECU can calculate the
sensor resistance depending on the voltage variation
of the sensor so as to achieve the temperature
information of the engine.
Fault diagnosis：The subsequent electronic device
of intake air pressure sensor can detect faults such
as open circuit, short circuit and damage to sensor,
etc. When ECU detects output signal from the
sensor falls beyond characteristic curves, it shall
judge that something is wrong with the sensor. For
example: when air intake pressure is higher than
upper limit, or lower than lower limit, the ECU will
judge as the breakdown of the sensor (The intake
pressure is below the lower limit during engine
start, however the ECU can judge the engine start
working condition) and at the same time turn on
Intake air pressure and temperature sensor
Circuit for sensor of air absolute pressure and
temperature in intake manifold
Pins:
1 Intake
ECU62#)
air
pressure
signal
(corresponding
2 Standard 5V power supply (corresponding
ECU64#)
3 Sensor earth wire (corresponding ECU65#)
4 Intake air temperature signal (corresponding
ECU55#)
engine trouble indicator to run under trouble mode.
Recover Solution: In case of the temperature
sensor failure, the system will set at one fixed
temperature grade (approximate 50oC) and the
engine will enter into trouble mode. In case of
pressure sensor failure, the intake pressure will be
set as 1024MBAR while the actual air intake
volume is calculated based on the throttle position
sensor and the engine speed. In case the throttle
position sensor is failure at the same time, then the
intake pressure will be set at 600Mbar. Under all
failure working conditions, the system self-learning
function will fail.
Note: In case of intake air pressure sensor failure,
the vehicle may not ignite and start normally.
When the pressure sensor signal wire is short-circuit
towards the 5V or 12V power supply, the vehicle
may not ignite and start normally.