Exhaust Backpressure Sensor Before Exhaust Turbocharger

Exhaust Backpressure Sensor Before Exhaust Turbocharger

Exhaust backpressure sensor before exhaust turbocharger
The exhaust backpressure sensor is secured by a holder on the engine (to protect it from high temperatures). The exhaust backpressure sensor is connected to the exhaust manifold via a hose and a pipe.

Functional description
The Digital Diesel Electronics need the exhaust backpressure sensor before exhaust turbocharger for optimum control of the exhaust-gas recirculation rate. By using the exhaust backpressure sensor and exhaust-gas temperature sensor, the Digital Diesel Electronics are able to adjust the exhaust-gas recirculation rate more precisely and efficiently.
A metal membrane in the exhaust backpressure sensor converts the exhaust back pressure into a displacement which is converted into a voltage signal by 4 pressure-sensitive resistors. The measuring range of the exhaust backpressure sensor lies at 100 to 500 kPa absolute, which corresponds to a voltage of 1.0 to 4.5 volts.







Structure and inner electrical connection
The exhaust backpressure sensor is connected with a 3-pin plug connection.
The sensor is supplied with 5 Volts by the engine control.







Characteristic curve and setpoint values
The exhaust back pressure information is sent to the engine control via a signal line. The signal for evaluation of the exhaust back pressure fluctuates depending on the pressure. The measuring range is from approx. 1.0 to 4.5 Volt. The measured exhaust back pressure is engine-specific.







The 6-cylinder diesel engine with 3 exhaust turbochargers has a deviating characteristic curve:







Observe the following setpoint values for the exhaust backpressure sensor:

Size Value
Voltage range 4.9 to 5.1 V
Operating pressure 1.0 to 5.0 bar
Optional: 0.6 to 6.5 bar
Response time less than 5 ms
Maximum output current 15 mA
Temperature range -30 °C to 120 °C

Diagnosis instructions

Failure of the component
If the exhaust backpressure sensor fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Exhaust-gas recirculation is deactivated

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