Rail pressure sensor pdf

This pressure is monitored by a pressure sensor and the difference between the nominal rail pressure value and the measured one is the input signal for the controller. In control terminology , the rail pressure is the system output while the position of the actuator used to control the rail pressure is the system input. There are a number of approaches to control the pressure in the common rail. One way is to supply more fuel than is needed to the common rail and use a high pressure regulator—commonly referred to as a pressure control valve—in the high-pressure circuit to spill the excess fuel back to the fuel tank.

In this approach, the pressure control valve position is the control system input. While this approach was used exclusively in some early fuel injection systems such as those with Bosch CP1 pumps Figure 1 and Figure 2 , poor efficiency and an excessively high fuel return temperatures can result. Another approach is to meter the fuel at the high pressure pump to ensure that only the amount of fuel required by the injectors is supplied to the common rail.

A number of pump metering approaches are possible. One common approach is to meter the fuel drawn into the pump inlet metering with some type of inlet metering valve IMV —sometimes also referred to simply as a fuel metering valve FMV. When the solenoid valve is powered off, the valve will close the orifice A on the top of control piston, the injector is forced close by the pressure forced on the piston build by common-rail.

When the solenoid valve is powered, the orifice A is opened, the pressure in control room will reduce sharply, the control piston rises up, the injector begins to inject; When the solenoid valve is closed, the pressure in control room will rise again and force the piston went down and close the injector to finish the injection.

The spring on injection module is used to avoid the backflow of fuel when the pressure of the common-rail has not www. The regulating value, which is shown in Fig.

The force is strengthened by magnet which is controlled by duty cycle of related signal. Common-rail is connected to high-pressure pump and injector through high-pressure oil pipe with larger internal diameter. The volume of common-rail can keep the pressure fluctuation caused by oil pump and oil injection as small as possible, meanwhile it can also help to build the pressure quickly when engine is starting.

This generation of system made the maximum pressure up to MPa, there were also many new technologies used on it such as high-pressure pump with oil regulator, updated solenoid valve injector and multiple injection. This kind of system has higher injection pressure, compactly injector, smaller size, small fluctuation of oil injection; it also used close-loop control and multistage injection technology.

This was a breakthrough in realm of diesel common-rail injection technology. Injection pressure is the characterization parameter of the 1st and 2nd generation system, the injection of 1st system can reach to MPa, Mpa the 2nd generation can reach. For the 3rd generation, the characterization parameter is high technology.

The pressure of this generation is maintained on Mpa. Due to the use of highly integrated piezoelectric injector, the piezoelectric actuator is more close to the needle valve, which make the hydraulic response time of the system more reasonable. Thus, the response time of the piezoelectric injector is twice quicker than any other electromagnetic injector. In old common-rail system, the injection process can only be separated into parts; it can be separated into any amount of parts in the 3rd generation.

Through the quantity of oil set for partial load is decreased, the accuracy is increased. What shown in Fig. Oil is sent to high-pressure pump with oil regulator by low-pressure electric oil pump. The allocation unit separates the oil into to flows, one flow is sent to the pump, the other flow is used to cool the transmission structure and lubricate the gear.

The oil is sent to common-rail after its pressure is built to MPa by the high pressure oil pump. The pressure sensor tightly equipped on the rail can get the pressure of common-rail in real time;the allocation unit integrated on high pressure pump can regulate the quantity of oil based on this pressure. The pressure regulation valve is used for sending more quantity of oil to the injector in acceleration condition.

This valve is controlled by ECU according to working condition to regulate the start time and duration of injection; it can also shape the injection curve the phase, inject time and quantity softy. In order to regulate the pressure of the oil rail, two sides of the rail are both equipped the newest pressure sensor and pressure regulation valve.

Compared with classic injector, the changeable coaxial injector will be totally different in orifices, including number, location,diameter, shape etc. The changeable coaxial injector shown in Fig. The first side of orifices are lower flow ones, they supply the little amount of oil which is needed in the early phase of combustion, this can make the combustion process more stable, thus the noise during combustion will be decreased.

When the engine is in full load, the second side of orifices with bigger diameter will open, this make it possible to inject accuratelyquantity of oil into the combustion room in a very short time, this can meet the need of the largest power of diesel engine. BOSCH is developing another kind of common-rail system with hydraulic intensifier. The design is that the high pressure oil pump force the oil into common-rail until its pressure reaches MPa, then the oil flows through high-pressure oil pipe into the injector, after flowing over a special convert piston, the pressure of oil will increase to more than MPa.

Due to the high pressure, a large amount of oil that the combustion need could be inject through very tiny orifices, which means the thin spray of oil will be more easily to mix with the air, the combustion will surely be cleaner and more efficient [13]. How to make the engine operate more stable, efficient, flexible is the most important question we are going to solve.

Does this injector actuation cycle work? YES Injector 1 is not malfunctioning, malfunction with injector 1 control circuit. Also check for insulation between these 2 connections. NO Injector 1 malfunctioning, replace the cylinder 1 injector. Check that the injector correction value is correctly programmed into the ECM. Check that the knock sensor is secure on the engine.

If the DTC persists, replace the cylinder 1 injector. NOTES Special notes: When this DTC appears, the idle speed is stuck at rpm, with engine noise, unstable engine speed, reduced engine performance and malfunction indicator light comes on level 1. YES Injector 2 is not malfunctioning, malfunction with injector 2 control circuit. NO Injector 2 malfunctioning, replace the cylinder 2 injector. Check that the injector correction value is correctly entered on the ECM. If the DTC persists, replace the cylinder 2 injector.

CC Switch off the ignition and wait 15 seconds. Check the connection and condition of the injector connector. Check the condition of the ECM harness connector F YES Injector 3 is not malfunctioning, malfunction with injector 3 control circuit. NO Injector 3 malfunctioning, replace the cylinder 3 injector.

If the DTC persists, replace the cylinder 3 injector. NO Injector 4 is not malfunctioning, malfunction with injector 4 control circuit. YES Injector 4 malfunctioning, replace the cylinder 4 injector. If the DTC persists, replace the cylinder 4 injector. DEF : No signal 3. Check the condition of the ECM harness connector E61 and replace it if necessary. Check the connection and condition of the fuel flow actuator connector.

Measure the resistance between the terminals 1 and 2 of the fuel flow actuator. DEF : Permanent low signal P 2. DEF : Above maximum threshold 5. DEF : Inconsistency 6. DEF : At maximum stop 7. DEF repair if necessary. DEF 4. DEF Visually check that the turbocharger circuit is leak tight.

DEF Repair if necessary. DEF Remove the air supply ducts and check that they are not blocked. With the engine stopped, the pressure should be approximately the same between the two sensors. Replace the TC boost pressure sensor if necessary. Check the turbocharger. DEF, 2. DEF, 7. Check the tightness of the cylinder and repair if necessary. Check the valve clearances and adjust them if necessary. Check the air inlet conduits and the EGR valve and clean them if necessary.

Replace the injector. Check the conformity of the injectors fitted to the vehicle in relation to the type of vehicle and engine number low injector, high or very high pressure. Check the knock sensor connection. DEF : Additional teeth 6. DEF, 3.

DEF, 6. DEF present: engine stops and malfunction indicator lights up level 1. DEF, 5. Check the condition of the crankshaft position sensor harness connector and repair if necessary. Check that the flywheel ring gear is not suspected missing teeth. Check the condition of the camshaft position sensor harness connector and repair if necessary.

If necessary, replace the sensor. Check the timing gear setting. Refer to "EM section". Check the condition and connection of the glow relay harness connector.

Change it if necessary. Check the condition and connection of the glow plug harness connectors. Change them, if necessary. Measure the resistance of each glow plug. If not, replace the suspected plugs. Check the condition and connection of the glow relay unit connector.

DEF : Inconsistency 4. DEF : Valve jammed 5. Starting problems, or even impossible when cold, with malfunction indicator lights up level 1 ". Check the condition and connection of the EGR volume control solenoid valve harness connector and repair it if necessary. Difficult to start engine or even impossible when cold. Check the condition and connection of EGR volume control solenoid valve harness connector and repair it if necessary. Measure the resistance at the EGR volume control solenoid valve harness connector terminal.

DEF : Above minimum threshold 2. Check the condition of the EGR volume control solenoid valve harness connector and repair if necessary. Also check there are no malfanctions in the ABS part or in the system which supplies the vehicle speed. Carry out a trouble diagnosis on the multiplex network.

LAN section Refer to the trouble diagnosis for the keyless vehicle function. Check the pressure sensor connection. Check the battery voltage when the ignition is switched on. Check the condition of the battery terminals. Check the vehicle's charge circuit. Check the condition of the ECM E61 harness connector. Deal with the DTC even if it is stored. Check the switch connection and repair if necessary.

Check the condition of the ECM harness connector E61 and repair if necessary. Check that the switch is working. DEF : Memory self-test 6. DEF : Non refreshed watchdog 7. DEF : Interference on the injector control line 8. Check that the individual injection correction value matches the injectors.

If NG, write the individual correction value codes see "Trouble diagnosis - Introduction". If the value corresponds correctly to the injectors, replace ECM. DEF 5. DEF 8. DEF Follow the instructions to confirm repair. Malfunction indicator lights up Level 1. Check the condition and connection of all the sensor connectors as follows: — engine coolant temperature sensor — turbocharger boost pressure sensor — common rail fuel pressure sensor — APP sensor — EGR valve position sensor — camshaft position sensor Repair if necessary.

If the DTC persists, apply the trouble diagnosis strategy to each sensor supplied by an external terminal. Check the condition of the APP sensor harness connector. Check the insulation to ground of the connection on terminal 18 of ECM harness connector E Check the insulation between terminal 18 and terminal 12 on ECM harness connector E Check the condition of the APP harness connector and repair it if necessary.

Check the condition of the APP sensor harness connector and repair it if necessary. Replace the ECM. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability.

Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation not independent. Diagnostic Procedure 1. Turn ignition switch "ON". YECA Check that the print out data is matched with above.

Application condition: engine off, ignition on. PR Engine speed Gives the engine's In the event of a rotational speed in rpm. This malfunction, apply parameter is controlled the trouble diagnostic External air by the BCM and procedure for this 5 temperature transmitted to the malfunction injection on the described in the BCM multiplex network.

This malfunction, apply Warm: 50C value is given by the the diagnostic Fuel 7 fuel temperature procedure for temperature sensor. Fuel temperature sensor circuit.

PR Atmospheric Gives the atmospheric If not consistent, pressure pressure in mbar. PR Rail pressure Gives the pressure of In the event of a Warm or cold the diesel in the malfunction, apply - 90 bar injection rail in Bar.

Rail pressure sensor Default value: Bar. PR Vehicle speed Gives the vehicle speed Test the multiplex in kph. This parameter is network. This trouble diagnosis. The coolant pressure sensor should not be suspected. Satisfactory engine operating conditions coolant temperature, engine load etc. The vehicle is not in a specific movement phase hill start or stop etc.

PR Refrigerant Gives the value in BAR If there is a problem: pressure for the refrigerant fluid apply the diagnostic in the system. If the DTC persists, replace the refrigerant sensor. PR Engine speed Gives the engine's In the event of a rotational speed in malfunction, apply rpm. The fans are prevented from operating under certain coolant temperature conditions when driving. Gives the engine's In the event of a rotational speed in malfunction, apply rpm. This malfunction, apply parameter is controlled the diagnostic by the Inteligent Key procedure for this External air 2 unit or BCM and malfunction temperature transmitted to the ECM described in the on the multiplex Inteligent Key unit or network.

BCM document. Inlet sensor voltage delivered by the 4 temperature computer to supply the sensor voltage inlet temperature sensor PR Engine speed Gives the engine's In the event of a rotational speed in rpm. Test conditions: Engine at idle speed. PR Engine speed. Gives the engine's In the event of a Cold: rpm V rotational speed in malfunction, apply Warm: rpm rpm. The UCH should request the injection to Compressor be engaged. The 2 engagement refrigerant pressure request sensor should not be faulty.

The vehicle 3 authorisation is not in a specific movement phase hill start or stop etc. This parameter network. This diagnosis. PR Fuel flow Shows the fuel flow None. Default value: Bar. PR Rail pressure Gives a theoretical None. Engine optimum engine Rail pressure 4 starting pressure operation. Gives the engine's In the event of a Cold: rpm V rotational speed in malfunction, apply the 6 Engine speed Warm: rpm rpm.

This malfunction, apply parameter is controlled the diagnostic External air by the BCM and procedure for this 2 temperature transmitted to the malfunction injection on the described in the BCM multiplex network. PR Atmospheric Gives the If not consistent, pressure atmospheric check pressure in mbar.

PR Inlet pressure Shows the pressure in the inlet circuit in mbar. PR Air flow Air flow estimated by None. Inlet sensor voltage delivered by the 4 temperature computer to supply sensor voltage the inlet temperature sensor PR Engine speed.

Check the condition of the turbocharger air temperature pressure sensor connections. If necessary replace the sensor.

Check the condition of the engine coolant temperature sensor connections. Measure the resistance between terminals 1 and 4 of the coolant temperature sensor. If the value is incorrect, replace the engine coolant temperature sensor. NO Carry out the required repairs. Is the low pressure circuit connection correct?

YES Look for leaks on the unions. YES Carry out the required repairs. Are there leaks in the hoses and unions? NO Check the correctness of the diesel filter. NO Replace the filter with an original part. Is the diesel filter correct? Is there water in the fuel filter? YES Drain the fuel filter. NO Bleed the low pressure circuit. Place a container under the filter: Check for air bubbles in the fuel filter. Are there any air bubbles in the low YES — Pump using the vacuum pump until pressure circuit?

NO Low pressure circuit OK. Is the charge circuit correct? YES Check the fuses. Are the fuses correct? Is the ECM relay working properly? NO Replace the relay. YES Test the engine ground. Are the engine ground correct?

Is there diesel in the injector wells? YES Injector ice leak, replace the injector. Can you hear the valve moving? NO Carry out test If test 11 is OK, replace the injector. YES Compare the return flow of the four injectors when hot using a measuring cylinder. See TEST 9. Does one of the four injectors have a YES Replace the injector with an unusually greater return flow than the others? Is there a noticeable change in engine NO Replace injector i noise?

Carry out the same test on the other cylinders to identify a possible suspected injector. The injector is sound. NO Check the condition of the air filter.

Air filter OK. NO Replace the air filter with a new part. YES Check that the inlet manifold is not obstructed dirty. Is the inlet manifold blocked? YES Clean the inlet manifold. NO Air circuit OK. Are the connectors poorly locked? YES Lock the connectors correctly. It is possible to check the high pressure supply pump capacity by carrying out the following procedure: — With the ignition off, disconnect the low pressure actuator from the pump IMV brown connector and connect a test adaptor test IMV.

The starter will cut out automatically after 5 secs. Is the rail pressure greater than bar? The pump can supply the operating pressure. Switch the ignition back on, and clear the injection faults using the fault finding Repeat the test when cold.

Coolant tool. NO Make sure that the ignition circuit is working correctly minimum engine speed rpm. Switch off the ignition and reconnect the 4 injectors and low pressure actuator electrically. Switch the ignition back on, and clear the Carry out fault finding on the injectors by checking injection faults using the fault finding tool.

Carry out TEST There is a command that performs a leak test on the high-pressure circuit when the engine is running. This command can detect a leak on the high-pressure circuit if a union is improperly fitted or bolted, but cannot detect a small leak if a union is not torque tightened.