Cause of rail pressure valve opening failure

Possible causes of opening failure of rail pressure relief valve:

1, oil return is not smooth;

2, rail pressure sensor or its line damage;

3. Fuel metering valve is damaged;

4, fuel injector blockage;

5. Pressure relief valve failure;

6. Ignition signal is occasionally lost during engine operation;

7, crankshaft, camshaft sensor wire harness inserted;

8, crankshaft sensor failure;

9. The position of two and two lines of crankshaft sensor is opposite (4G\4E);

10, low pressure oil resistance is too large;

11. ECU fault;

12, throttle line (from high to low probability of failure)

Personally recommended check steps (arranged according to the probability of failure causes) :

First, it is necessary to determine whether the failure of the "track pressure relief valve opening" fault of the broken car is accidental or always exists. If it is accidental, it is best to collect the data when the fault occurs with the car, and focus on the changes of the actual and theoretical rail pressure when collecting data. If the actual rail pressure moment is much greater than the theoretical rail pressure moment when the vehicle is under heavy load, the most likely cause of this failure is poor oil return. If it is the cause of poor oil return, this fault usually occurs when the engine is under heavy load (full load and uphill).

Second, to judge whether the rail pressure sensor is normal, specific can be tested by the following steps: The rail pressure sensor has three lines, respectively for the ground line, rail pressure signal line (middle one), 5 volt reference voltage line, in the ECU is powered on but the engine does not start, at the same time does not remove the rail pressure sensor connector under the premise of measuring the rail pressure sensor signal line voltage in 0.5-0.55V (normal range); If the ECU is powered on but the engine does not start, pull out the contact of the rail pressure sensor to measure, the three cables of the rail pressure sensor should be as follows: rail pressure reference voltage 5 V, rail pressure signal cable 5 V, and one ground wire.

In addition, rail voltage signal line voltage value in addition to the multimeter measurement, but also through the diagnostic instrument on the actual rail voltage value of this parameter. According to the above criteria, if any abnormality is found during the check, check the related wiring.

Third, check whether the fuel metering valve is normal and whether the resistance value of the fuel metering valve is in the normal range of 2.6-3.15 ω. If so, please check whether the driving voltage of the fuel metering valve is 24 volts.

Another clue can be found from the value of "oil metering valve set current" on the diagnostic instrument. When the engine is powered on but not started and the metering valve is faulty and the line is open, the oil metering valve set current value is: 400mA; After starting, the normal current range is about 700-1500mA;

Fourth, if the engine in the process of running ignition signal line power, fuel injector due to power failure will stop spraying, at this time the engine due to inertia rotation, driving oil pump will have passed the metering valve oil pressurization and transport to the common rail, so that the rail pressure momentarily too high, resulting in pressure relief valve burst failure. To solve this problem, we can judge whether there is power failure by monitoring the change of the engine state value after the vehicle (when the engine state value is 48, it means that the ignition signal is lost).

Fifth, check and monitor engine operation parameters to determine whether the injector works normally; Can refer to the parameter of rail pressure component: the normal range of rail pressure control product component -2000 to +2000mm/s, if the rail pressure component greatly exceeds this range, and accompanied by the failure code "rail pressure control mode fault 7, 10". Then the possibility of fuel injector blockage is relatively large, which will also lead to the opening failure of the rail pressure relief valve of the engine under heavy load.

The above situation is the common reason for opening this fault of the rail pressure relief valve. If the above five steps have been checked and still cannot be solved, you can continue to conduct investigations according to the possible causes summarized above.