The necessary conditions for BOSCH common rail injector to start fuel injection.
The necessary conditions for BOSCH-common rail common rail engine injector to start fuel injection
Common rail pressure exceeds the minimum set value (>350bar)
Synchronization signal is normal:
Sensor signal ≥ trigger threshold (related to air gap and speed)
The phase is correct
1: Check whether the rail pressure sensor is normal
Unplug the rail pressure sensor and check the rail pressure sensor harness end with a multimeter: 5V between 1-2, 5V between 1-3 is normal, or you can use a pin of multi-meter to connect 2 holes, another pin on the table,if 4.8. v is normal, the third hole, is about 4.8v is normal.
Note: 1 is the power ground, 2 is the signal, 3 is the power supply
Second, high idle speed
High idle speed means that only one speed is 1100 rpm after the engine is started, and the accelerator pedal is invalid.
High idle speed is generally caused by a throttle problem.
The throttle of the common rail engine is a double potentiometer type. Check the throttle line: the first voltage should be 5V, the second voltage is 5V normal; see the first signal voltage of the diagnostic scanner is about 2 times the second signal voltage which is normal.
If the first voltage is not 5V, it is 3.2V (the same voltage as the common rail). At this time, remove the rail pressure sensor, and the voltage of the throttle becomes 5V, indicating that the rail pressure sensor fails and the common rail assembly is replaced.
ECU damage determination
Reason 1: Lose self-test function; (Occasionally lost, everything else is normal, ECU also has bad possibility)
Reason 2: Accelerated abnormality;
Reason 3: Excluding all peripheral line faults, the problem cannot be solved. Consider the ECU internal program problem, the probability is very small.
Fourth, the parameters to be noted on the diagnostic instrument
Set rail pressure value
The difference between the actual rail pressure value and the set rail pressure value should be less than 200hpa, otherwise stated
Actual rail pressure
The starting instant sync signal should fluctuate between 3-48, and finally 48 means signal synchronization.
Cycle fuel injection
Rail pressure control integral
When the idle speed is between -2000 and +2000 is normal; less than -2000 indicates that the pipeline is blocked or leaking, the diesel is not smooth; more than 2000 indicates the injector, backflow pipe leak.
Rail pressure closed loop state
Torque limit state
Cooling water temperature
Pressure after intercooling
Description of rail pressure: When the actual rail pressure value is less than the set rail pressure value of 200hpa or more, the fault code is reported:
P1011 rail pressure closed-loop control mode fault 0–the rail pressure is lower than the target value; this fault may be reported as an instant, then the fault will disappear when the difference between the two is within the allowable range.
The cause of this failure is a low (slight) blockage of the low pressure circuit (most likely the fuel filter is clogged)
The rail pressure cannot be established, ie the engine cannot start. There are two possibilities that rail pressure cannot be established: one is that the low-pressure fuel circuit is blocked or leaked, and the other is that the high-pressure fuel circuit is leaking (due to the difference in fuel content, the water content may cause the cylinder injector to become stuck, which may cause high-pressure fuel. If the leakage causes the rail pressure to be unable to be established, it cannot be started. The method can be judged; the fuel return of each cylinder can be checked and compared to determine whether the injector is good or bad. A historical fault code may be displayed from the diagnostics at this time:
P1014 rail pressure control deviation fault—mode 7, rail pressure control deviation fault—mode 10.
◆ Rail pressure closed loop state: 0 represents open loop state, 3 represents no diagnostic closure, 5 represents closed state, and 14 represents stomping state
◆Torque limit status
Bit 0: Engine Torque Limit in Error Status Bit 1: Maximum Torque Limit
Bit 2: Maximum Speed Limit Bit 3: Smoke Limit
Bit 4: Oil limit in error state Bit 5: Thermal protection limit
Bit 6: Drive Torque Limit in Error Status Bit 7: Transmission Torque Limit
Bit 8: Pump Balance Maximum Torque Limit
◆ Synchronization status (the number of the synchronization signal greater than 12 is less than 48 is garbled, 48 is the synchronization state)
Rail pressure release valve opens
If the engine accelerates up to 1700 rpm, and the fault light is on, the fault code read out is: the rail pressure release valve is open. At this point, you can feel it by hand: you will find that the temperature of the common rail return line is 50 °C higher than the temperature inside the common rail. At this time, the rail pressure in the common rail is a constant value of 720,000hpa!
Remedy: After turning off the key switch, turn off the whole vehicle for 20 seconds or even a few minutes, then turn on the power of the whole vehicle, turn on the key switch to start, the rail pressure release valve should be reset, and the starting is normal.
There are two possibilities for the opening of the rail pressure relief valve: the fuel metering valve on the high pressure pump is open and the return line is blocked. If these two conditions exist, the bleed valve cannot be reset.
When it is not possible to start, try to open the fuel metering valve one or two times. When the fuel metering valve is opened, the high pressure pump is equivalent to the mechanical pump. At this time, the rail pressure relief valve is opened. If the valve is opened more times. If it is too much, it will not be automatically reset. It is equivalent to the failure of the rail pressure relief valve. It is necessary to change the common rail. Therefore, generally do not pull the fuel metering valve.
How to read the fault code through the fault indicator
The ignition switch is ON → standby and operating conditions can be carried out → (for the diagnostic request switch is the automatic reset switch) press – release the diagnostic request switch; (for one open and close and then press back) can be activated Flash code → only one fault code is flashed for each operation, and all the fault codes can be read in sequence; the corresponding fault can be detected according to the fault code table;
How to manually clear the fault code?
When there is a fault in the engine, this method is generally not used. Once the fault code is cleared, the electronic control maintenance personnel can not find the cause of the fault when reading the fault code with the diagnostic instrument, it is difficult to take corresponding measures to repair,When the engine is all normal, you need to try this method when you need to clear the historical fault. Sometimes it can’t be cleared. It is best to operate it through the diagnostic device.
Turn off the key switch for about 30 seconds → turn on the diagnostic request switch on the meter → immediately turn the key switch to the ON position → for 4 to 8 seconds → turn off the diagnostic request switch on the diagnostic request switch on the meter.