Page 244 - Foton Workshop Manual - Aumark (BJ1099)

11-18 ENGINE CONTROL SYSTEM - INTAKE PRESSURE/TEMPERATURE SENSOR

INTAKE PRESSURE/TEMPERATURE SENSOR

1. Principle of work
Adopting the speed-density air measurement method, the system detects the air
amount in engine after inter-cooling,to correct the fuel-injection quantity, etc..
The intake air temperature sensing element is a negative temperature coefficient
(NTC) resistance, whose resistance value declines with the increase of intake air
temperature.Engine ECM detects the change of intake air temperature through a
internal comparison circuit.
2. Function and installation
The sensor is composed by absolute pressure sensor and intake air temperature
sensor, to measure the pressure temperature value after inter-coolingand feed it
back to ECU as the basis for supercharge pressure control. It is installed in the
intake tube after intercooling and before throttle.
3. Fault phenomenon and judgment method
(a). Fault phenomenon: Flame out and poor idling, etc..
(b). General causes for faults:
• Abnormal high pressure or large reverse current in using process.
• Vacuum unit is damaged in maintenance process.
(c). Precautions for maintenance:
• Impacting vacuum unit by high pressure gas is prohibited in maintenance
process;
• Check whether vacuum hole of sensor is blocked, and dispose it in time;
• Upon replacing sensor after fault detection, check whether the engine output
voltage and current are normal;
• Use press-in method rather than hammering method while install.

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