This topic deals with non start / poor start problems affecting the Vauxhall Vectra range of vehicles using the 2.0 diesel engines fitted with an electronic diesel engine management system.

There are two versions of the 2.0 diesel engine available; a low pressure turbo (X20DTL) version and a high pressure turbo (X20DTH) version. Both versions make use of the Bosch EDC MSA15 diesel engine management system which is commonly described as a “drive by wire” system. This is where the conventional accelerator cable has been replaced with an accelerator pedal sensor and a diesel injection pump electronic control module (ECM) which is fitted to the top of the diesel injection pump.

Introduction

The signal from the accelerator pedal sensor as well as other sensor signals from the diesel engine management system are then processed by the EDC MSA15 ECM (which is usually located in the area between the windscreen and the bulkhead in the engine compartment). From these sensor signals the EDC MSA15 ECM then supplies an engine load request signal to the diesel injection pump ECM.

The diesel injection pump ECM processes the engine load request signal. From this signal the diesel injection pump ECM controls the operation of the diesel fuel injection pump for both engine speed, load and emission requirements.

Note. The diesel injection pump ECM is an integral part of the diesel injection pump assembly and cannot be removed and replaced separately from the diesel injection pump.

Other features of the Bosch EDC MSA15 diesel engine management system include an injection pump immobiliser control unit. On previous versions of the diesel engine management system, an immobiliser control unit was fitted to the back of the diesel injection pump to control the operation of the stop solenoid. If an incorrect coded signal was received by the immobiliser control unit, the stop solenoid would be de-activated and the engine would not start.

On the EDC MSA15 diesel engine management system, the diesel injection pump ECM receives a start signal from the Bosch EDC MSA15 ECM to initiate fuel flow control in the injection pump. If the Bosch EDC MSA15 ECM has not received a signal from the immobiliser control unit, a start signal will not be received by the diesel injection pump ECM. The diesel injection pump ECM will then switch the fuel control inside the pump to the closed position, preventing the engine starting.

System Overview

Non-start Poor-start problems

As indicated from numerous calls on the telephone help line, the most common reasons for non start or poor start faults on this system are still related to conventional diesel problems. In particular, air ingress into the diesel fuel system is still the most common cause of non start or poor start problems.

A classic scenario of an air ingress problem is where the non start or poor start problem develops in the mornings after the vehicle has been left overnight. Then if the vehicle eventually starts, the engine appears to run on one or two cylinders and gradually, as the air is expelled from the fuel system, the remaining cylinders operate OK. The fault would then usually not present itself again until the following morning. Whilst repairing an air ingress problem is not difficult, locating the actual area of the air ingress can be time-consuming.

On the Vectra (and also common to the Astra) 2.0 range of diesel vehicles there are two main areas where air ingress is common. The first area is the fuel filter which also incorporates the fuel heater element. The second area is the diesel injector feeder rail seals. These two areas are prone to failure and allow air ingress into the fuel system.

Fuel Filter Air Ingress

The Bosch EDC15M diesel engine management system has a fuel filter heater incorporated within the fuel filter assembly. The replacement fuel filter element is the same for both heated and unheated fuel filter assemblies. When fitting a new fuel filter element to vehicles with the heated fuel filter assembly, it should be noted that the filter element should be installed without the centre seal ring and support ring which may still be included in the replacement filter kit.

The most common area of air ingress on the fuel filter assembly is caused by over tightening of the centre bolt of the fuel filter housing.

Excessive over tightening can result in distortions of the fuel filter housing resulting in air ingress.

Vauxhall recommend that the centre bolt should be tightened to a torque of 6 Nm.

In addition, carefully inspect both the fuel inlet and outlet pipes on the fuel filter assembly. These pipes have been reported to go brittle and crack, causing air ingress problems.

Diesel injector feeder rail seals

The second main area of air ingress is the diesel injector feeder rail seals. On the Vauxhall 2.0 diesel engines the fuel supply to the diesel injectors is supplied through rails that run through the cylinder head under the camshaft. In the event of replacing the diesel injector feeder rail seals or the diesel injectors it will be necessary to remove the camshaft and followers to gain access.

If it is suspected that the air ingress problem is caused by the diesel injector feeder rail seals, it is possible to first try re-tightening the feeder rail retaining bolts, which does not require removal of the camshaft and followers. This may create a better seal and fix the fault. Note that the following procedure must be carried out correctly and over tightening the retaining bolts may cause damage.

Procedure for re-tightening the diesel injector feeder rail retaining bolts

• Remove the camshaft cover to gain access to the feeder rail retaining bolts. The retaining bolts can be seen between the inlet and exhaust camshaft profiles for each cylinder.
  
• Slacken each feeder rail retaining bolt.
  
• Tighten the feeder rail retaining bolt as tight as possible by hand using a socket and socket extension bar only.
  
• Then using a ratchet tighten each feeder rail retaining bolt a further 360 degrees only.

If this procedure does not cure the air ingress problem with the diesel injector feeder rail seals, it will then be necessary to renew the diesel injector feeder rail seals. This procedure will require the removal of the camshaft and followers to allow the injector feeder rail to be removed.

After removing the diesel injector feeder rail from the side of the cylinder head, the diesel injector feeder rail sealing rings can be seen located on the top of each diesel fuel injector.

Note. Whenever the diesel injector feeder rail is removed from the side of the cylinder head. Always renew the second sealing ring, which is located on the front section of the diesel injector feeder rail.

Bleeding Procedures

On the Vauxhall 2.0 diesel engines (X20DTL & X20DTH), the procedure for bleeding the fuel system has changed from the earlier Vauxhall diesel engine management systems. On the earlier type diesel engine management systems it was not necessary to manually prime and bleed the fuel system after any work had been carried out on the fuel system components.

The earlier system was referred to as “self bleeding” where it was only necessary to crank the engine in bursts of ten-second maximum intervals with five-second cool down periods for the starter, until the engine started. Then the engine was run at fast idle speed for a couple of minutes until all of the air was expelled from the system. If the engine still idled roughly, the fast idle procedure was repeated as often as necessary until the engine was idling smoothly.

Vauxhall now recommend that with the introduction of the X20DTL & X20DTH engines the method of bleeding this system must be changed. Due to changes in the design of the diesel injector pump, Vauxhall only recommend bleeding the diesel fuel system using an external fuel pump. The external fuel pump is fitted inline (using suitable hose adaptors) to the fuel system close to the fuel filter assembly. Many types of external fuel pumps are now available for purchase commercially to “pre-bleed” these types of diesel injection pumps.

Installation and use of external fuel pump

Release the hose clamp (A) and disconnect the flexible fuel return line (C) from the metal fuel pipe (B). Connect the intake fuel pipe connection from the external pump to the flexible fuel return line and the pressure fuel pipe connection from the external pump to the metal fuel pipe using suitable hose clamps and hose adaptors.

Operate the external fuel pump for approximately three minutes without attempting to start the engine (Pre-bleeding). After this period of time has elapsed, crank the engine until it starts (maximum period of 40 seconds).

If the engine does not start during this period, wait for 20 seconds (to allow the starter motor and battery to recover) then repeat attempt to crank and start the engine.

When the engine has started, continue to run the engine with the external pump operating for a short period of time (approximately 5 minutes) to ensure all the air has been bled from the fuel system. Switch off the engine, remove the external fuel pump, reconnect the fuel return line and secure using new hose clamps. Re-start the engine and inspect the fuel system for leaks.

If it is suspected that air ingress is not causing the problem with poor or non start faults, it will then be necessary to check the electrical circuit of the Bosch EDC15M diesel engine management system.

i.e. Glow plug and wiring connections between the Bosch EDC15M ECM and other sensors and control units on the vehicle. To assist with these checks the following page details the generic wiring for the Bosch EDC15M diesel engine management system.