high pressure diagnostic uk v2[1].3

Technical service memo �VERSION 2.3

� DATE 20/10/04 Delphi Diesel Systems / Launch Team Common Rail PAGE 1/13

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� NAME SIGNATURE Author Benoit COSSON

Christophe GARNIER Olivier LEDRU Olivier BENOIT

Approved by Frédéric DAVID

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High Pressure Diagnostics



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1.0 04/05/02 Creation. Benoit COSSON Christophe GARNIER Olivier LEDRU Olivier BENOIT

Frederic DAVID

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1. Introduction.................................... ............................................................... 4.

2. Symptoms ........................................ ............................................................. 4. �

3. Hydraulic system status analysis................ ................................................ 5. �

4. Diagnostics ..................................... .............................................................. 7. 4.1 Preliminary checks........................................................................................................................................... 4.2 Hydraulic system status analysis..................................................................................................................... 4.3 Static injector backleak test ............................................................................................................................. 4.4 Dynamic injector backleak test ........................................................................................................................ 4.5 Pump pressure generation capability .............................................................................................................. 4.6 Detailed diagnostic flow chart ..........................................................................................................................

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5. Values by applications………………………………………………………….... 13. �

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1- INTRODUCTION :

When it is necessary to check the rail pressure function on a faulty vehicle due to the observed customer effect, it is often difficult to decide which component of the system has really failed. It is essential to keep in mind the principles of the function of the Common Rail system:

1- Pressure production : the pump compresses the fuel at high pressure. 2- Pressure regulation : the pressure thus produced is accumulated in a rail and

measured and regulated (the rail pressure sensor, the ECU and the IMV function in a closed loop).

3- Pressure consumption : this pressure is finally consumed by the injectors (injection into the engine cylinders and injector management).

This means that a pressure fault may come from the producer, the regulator or the consumers. Simply studying the physical parameters of the rail pressure does not allow the disassociation of producer and consumer. 2 - SYMPTOMS : The engine won’t start or is difficult to start The engine stalls while running. Lack of power and dashboard warning lamps light : the recovery mode may lead to engine stop.



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3 – Hydraulic system status analysis : �

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In order to properly understand the fault codes linked to pressure control, it is necessary to analyse the hydraulic system status:

Pressure potentialConsumption

Pressure reserve necessary forcorrect functioning of the system

Pressuredemand

Capacity of the pump tosupply a flow at a givenpressureBackleak flow

Injec ted flow

Hydraulic flow balance is established as follows :

Injected flow + Backleak flow (Flow consumed)

= Capacity of the HP pump to supply the flow requested for a given Diesel fuel temperature and

pump inlet depression.



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The hydraulic flow balance is upset if :

consumption production

Injected flow

Backleak flow

Pump capacity

Pressure deficit

Increased backleak flow

consumption production

Injected flow

Backleak flow

Reduction in HP pump capacity

Pressure deficit

Pump capacity

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• The Injector backleak flow increases sharply, exceeding the pump capacity.

This can happen when particles disturb the internal injector sealing, increasing the backleak flow from one or more injectors.

Examples : Heavy contamination of the fuel Wear and tear on the pump leads to the production of metallic particles that will seriously disturb the injector function Mechanical wear in the injector.

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• The capacity of the pump to supply the required pressure is reduced due to internal pump wear or a fuel feed problem. �

Example : Presence of air in the low pressure circuit. Excessive negative pressure at the pump inlet (<-300mBar) Mechanical wear in the pump Excessive pump inlet temperature (>65°C)

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4 - DIAGNOSIS :

The following diagnostic flow chart summarises the various successive injection system checks for the isolation of faulty components.

Logical order for diagnostic operations

4-1 Preliminary checks : Check that: the fuel feed circuit is in good condition,

there is diesel fuel present in the system, there is no air (no bubbles or emulsion in the pipes), there are no high pressure circuit leaks, there is diesel fuel of the correct quality and type.

Carry out the Diesel filter test described in the technical service memos DT306_3 (Renault) or DT324_2 (Kia-Hyundaï) or DT326 (Ford),

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Engine starts Engine doesn’t start



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The following operations require a diagnostic tool capable of reading the rail pressure and the engine cycle speed (ERPM).

4-2 System hydraulic status test:

The following paragraphs explain the System Hydraulic Status test and describe how the test is carried out. The test allows the generation of a snapshot of the CURRENT capacity of the entire system to generate the high pressure required. There are 2 possible cases :

- The pressure measured is adequate and therefore the search for a system high-pressure build problem can be abandoned.

- The pressure measured is inadequate and complementary tests must be carried out to determine the cause.

The on-vehicle System Hydraulic Status test :

- The system must prepared for the test as follows : Disconnect the IMV electrically by disconnecting the BROWN connector on the High Pressure pump and disconnect the injector electrical connections so that they are no longer managed by the ECU. This will allow the maximum pressure to be reached.

- Turn the engine over on the starter for five seconds only : the five second period is critical, nothing is gained from exceeding the five second limit and it is dangerous to do so! NB : during test cranking, the engine cycle speed must exceed 200 RPM.

Perform this test in cold conditions, coolant temperature < 30°c.

The minimum pressure reached must be 1050 bars for all applications. If the rail pressure is below 1050 bars

� Use the following paragraphs (4-3 to 4-5) to isolate the faulty component(s) � at this stage, the system capacity can be regarded as insufficient

If the rail test pressure is above 1050 bars

� the root cause of the problem lies outside the capacity of the system to produce pressure

� use the routine diagnostic documents



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4-3 Static injector backleak test : The backleak flow volumes must be measured. If the engine will not start, it is only possible to measure the static flows (i.e. unmanaged closed injectors under high pressure). - Connect clear, 4mm internal diameter plastic tubes to all the injector backleak ears.

(the 4mm internal diameter is critical) - Plug the pump venturi connection.

(to prevent airlocks in the low pressure circuit) - Disconnect the brown IMV electrical connector and t he injector electrical connectors.

- Read the rail pressure and the engine cycle speed ( RPM) while cranking the engine on

the starter for 5 seconds. Do not exceed the 5secon d limit under any circumstances. NB : the engine speed during test cranking must be higher than 200 RPM

- Measure the quantity of diesel fuel obtained in 5 seconds in cms. Refer to the table

(appendix n°1 §5) and replace any injectors whose backleak exceeds the va lue given in the reference table. (See appendix n°1 for the particular case of contro lled starters)

- - Empty the plastic tubes, reconnect them and do the measure again with the new injector(s)

(after 5 second on the starter) and replace any injectors whose backleak now exceeds the value given in the reference table (appendix n°1 §5) .

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4-4 Dynamic backleak injector test :

In cases where the engine will run, the leak detection cycle allows the dynamic backleak flow to be checked ( while the engine is running) from 230 to 1400 bars.

- Connect the containers to the injector backleak pipes. - Plug the pump venturi connection. - (to prevent airlocks in the low pressure circuit). - Set up the diagnostic tool for the HP leak detection test. - Run the engine at idle for X seconds and launch Y consecutive leak detection cycles

(see reference table for X and Y values) . - Measure the volume of diesel fuel collected and refer to the tables in appendix n°1 §5 - Replace any injectors whose backleak volume exceeds the reference table values (see

the Container method technical service memo for further details).



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4-5 Pump pressure generation capability :

This test is designed to check the pressure generated by the pump when isolated from the pressure consuming elements of the system (see technical service memo “plugged rail”/ “rail bouché"). The "plugged rail”/”rail bouché" tool is required in order to carry out this test.

- Connect the plugged rail to the pump HP outlet and the rail pressure sensor connector to the plugged rail pressure sensor.

- Plug the engine rail inlet during the test to keep it clean for subsequent re-connection after the test.

- Disconnect the IMV flow actuator (brown electrical connector). - Read the rail pressure and the engine cycle speed ( RPM) while cranking the engine on

the starter motor for five seconds. Do not exceed t he five-second limit under any circumstances – nothing is gained from exceeding th e five-second limit and it is dangerous to do so! NB : the engine cycle speed must be greater than 200 RPM during the test.

- If the pressure reached during the test is less than 1050 bars, the HP pump must be replaced.

Plugged rail :

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4-6 Detailed diagnostic flow chart

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PRELIMINARY CHECKS (§4.1) - Check the Low Pressure circuit (air in feed circuit + injector return) - Check the fuel type ) Check for external diesel fuel leaks�) Carry out the “filter” test. See tecnical service memo "DT 306_3 (Renault) or DT 324-2 (KIA-

Hyundaï) or DT 326 (Ford)"�

HYDRAULIC SYSTEM STATUS (§4.2) Read the pressure while cranking for 5 seconds, IMV and

injectors disconnected in cold conditions (coolant temperature < 30°c). Pressure reading greater than 1050 bars ?�

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Check the low pressure circuit : Check the fuel guage pickup in the tank (air

locks or blocked orifice). Carry out a test with a clean test tank and filter.�

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STATIC INJECTOR BACKLEAK TEST (§4.3) Carry out the "tube test" :

Connect transparent tubes to the injector backleak ears, plug the venturi and measure the quantity of diesel fuel produced after 5

seconds cranking on the starter motor Backleak flow excessive ?

(Permissible flow level table available in appendix n°1 §5 ) ��

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��PUMP PRESSURE BUILD CAPACITY (§4.5)

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��B&��La pression lue est supérieure à 1050 bars ?�

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DYNAMIC INJECTOR BACKLEAK TEST (§4.4) Use the ISO leak detection test.

see. Technical service memo “Containers method". Is the backleak flow excessive ?

(Permissible flow level table available in appendix n°1 §5 ) �

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5. Values by applications for pipes and containers methods Annexe 1 :

Pipes method Containers method

APPLICATIONS Pipe length (values in cm)

Cranking time

Containers volume

(values in ml) Idle time Number of leak

detection cycle

Renault K9K700

(C4G26 only) Renault K9K700

(C4G26 execpt) Renault K9K704 Renault K9K702 Renault K9K722 Renault K9K728

10 cm

10 cm

10 cm 10 cm 8 cm 8 cm

5 s

5 s

5 s 5 s

1 action (1) 1 action (1)

20 ml

35ml

35ml 35ml 35 ml 35 ml

2 min

2 min

2 min 2 min 2 min 2 min

2 cycles

2 cycles

2 cycles 2 cycles 2 cycles 2 cycles

(1) : 1 starter button action with coolant temperat ure > 20°c.

Ford Lynx Ford Puma

20 cm 21 cm

5 s 5 s / / /

KIA/HUYNDAI

KJ29L 20 cm 5 s 25 ml 2 min 2 cycles

PSA DV4TED4 18 cm 5 s 37 ml 1 min 1 cycle

Ssang Yong D27DT

20 cm 5 s 38 ml 30 s 1 cycle

TATA Safari 3 Liters (BSII)

20 cm 5 s 50 ml 30 s 1 cycle

high pressure diagnostic uk v2[1].3

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