Ford Jaguar Fuel Common Rail Pressure Sensor 8W839F972AA

1. External line inspection

Measure the resistance values between terminal No.1 and terminal A08, terminal No.2 and terminal A43, and terminal No.3 and terminal A28 with a multimeter to judge whether there is a short circuit or an open circuit fault in the external circuit.

2. Sensor voltage measurement

Turn off the ignition switch, unplug the common rail pressure sensor plug, and turn on the ignition switch. Measure the voltage between the No.3 end of the sensor plug and the ground, the voltage between the No.2 end and the ground should be about 0.5V, and the voltage between the No.1 end and the ground should be 0V. Under normal conditions, the voltage at the No.2 end should increase with the increase of the throttle, otherwise it can be judged that the sensor fault signal output is abnormal.

3. Data stream detection

Read the data flow of the engine fuel supply system with a special diagnostic instrument, detect the idle state, the oil pressure change with the increase of the throttle, and judge the output voltage change of the rail pressure sensor.

(1) When the coolant temperature of the diesel engine reaches 80℃ and the diesel engine runs at idle speed, the output voltage of the rail pressure sensor should be about 1V, and the rail pressure of the fuel system and the set value of the rail pressure are both about 25.00MPa. The rail pressure setting value is very close to the rail pressure value of the fuel system.

(2) When stepping on the accelerator pedal gradually and increasing the speed of diesel engine, the data value of rail pressure system gradually increases, and the maximum values of rail pressure, rail pressure set value and actual rail pressure of fuel system are 145.00MPa, and the maximum output voltage of rail pressure sensor is 4.5V V.. The measured (for reference only) data flow is shown in the table below.

4, common fault phenomenon

When the common rail pressure sensor fails (such as unplugging), the diesel engine may not start, the engine will tremble after starting, the idle speed will be unstable, a lot of black smoke will be emitted during acceleration, and the acceleration will be weak. Different models adopt different engine control strategies. The specific faults vary from model to model.

(1) When the common rail pressure sensor fails, the diesel engine cannot be started.

(2) When the common rail pressure sensor fails, the diesel engine can start and run normally, but the engine is limited in torque.

(3) Common fault codes when the common rail pressure sensor fails (is lost),

① the engine can't start and run: P0192,P0193；;

② signal drift, engine torque limit: P1912, P1192, P1193.