Chimaera cut-out whilst driving/lose 4 cylinders

[HiAsAKite]

So there I was driving along yesterday, probably an hour into the journey, on the M25, when my engine gives up and just cuts out.

Couldn't restart for about 30's (would turn, but would not fire), when it started up and then ran, albeit the low idle was 2K revs when unloaded.

Idle then settled. Car cut out twice more on the same journey (driving along - engine just died on me - got it to safety managed to restart after 10-30s) and then just before I got home, lost a bank of cylinders. Fortunately was able to get home with just 4 cylinders.

All internal electrics, lights etc seemed to work ok, rev counter, dash worked etc.

Any thoughts?
Fueling seemed to work (as in I think fuel was injecting ok.

(NB - trying to nurse a cut out car on momentum alone across 4 lanes of the M25 in v. heavy traffic is frankly hideous!- and thanks to the kind driver behind me who clocked what was going and acted as a 'shield' for me!... thank you whoever you were!!)

[Steve_D]

Very little to go on at present but first thoughts.

If you lost the whole of one bank:-
• It is unlikely to be ignition as there is nothing in the ignition system that is specific to one bank.
• A general loss of fuel pressure such as the pump/relay/immobiliser would not affect only one bank.
• A lambda fault could.
• An ECU fault or its wiring could.
• If it is the offside bank then I have seen a problem where the injector earth wire underneath the coil mounting bracket rubs and shorts on the bracket….net result is all injectors on that bank are open all the time and flood that side of the engine.

Steve

[Pupp]

Steve_D said:

Very little to go on at present but first thoughts.

If you lost the whole of one bank:-
• It is unlikely to be ignition as there is nothing in the ignition system that is specific to one bank.
• A general loss of fuel pressure such as the pump/relay/immobiliser would not affect only one bank.
• A lambda fault could.
• An ECU fault or its wiring could.
• If it is the offside bank then I have seen a problem where the injector earth wire underneath the coil mounting bracket rubs and shorts on the bracket….net result is all injectors on that bank are open all the time and flood that side of the engine.

Steve

Err... not sure that bottom suggestion is quite right - aren't the injector pulses determined by the ECU switching the -ve side of the circuit to each injector; with the +ve being a common line back to one of the two identical relays in the footwell (other being the fuel pump)?

I certainly agree this is an injector related issue if a complete bank is dropping out

[Sardonicus]

If you are suspecting you lost a bank we have had a lot of rain check the ECU as not become damp or wet

[Loubaruch]

I had a similar fault a while back and traced it to a an intermittent connection on the ECU plug/socket.

Pin 11 feeds one bank and pin 13 the other bank. The ECU loom suffers a lot of bending and strain in the passenger foot well so not surprising that the connections sometimes fail.

I got fed up trying to sort out many problems here so bolted the ECU and relays to the bulkhead, no problems since:

http://www.bertram-hill.com/moving-the-fuse-panel....

[Steve_D]

Pupp said:

Steve_D said:

Very little to go on at present but first thoughts.

If you lost the whole of one bank:-
• It is unlikely to be ignition as there is nothing in the ignition system that is specific to one bank.
• A general loss of fuel pressure such as the pump/relay/immobiliser would not affect only one bank.
• A lambda fault could.
• An ECU fault or its wiring could.
• If it is the offside bank then I have seen a problem where the injector earth wire underneath the coil mounting bracket rubs and shorts on the bracket….net result is all injectors on that bank are open all the time and flood that side of the engine.

Steve

Err... not sure that bottom suggestion is quite right - aren't the injector pulses determined by the ECU switching the -ve side of the circuit to each injector; with the +ve being a common line back to one of the two identical relays in the footwell (other being the fuel pump)?

I certainly agree this is an injector related issue if a complete bank is dropping out

The injectors are not fired individually they are 'Bank' fired so the negative side of all the injectors on that side are commoned together and connected to the ECU. If this common wire shorts to earth anywhere all the injectors on that side will fire.

Steve

[HiAsAKite]

Ok- thanks folks.

So that the issue appears to impact one or both banks, by bank, suggests its an injectoring wiring/connection issue.

I will have a dig round and see if I can reposition or wedge the ECU to release load on the connector (its wedged between the battery box and outside footwell 'wall' at the moment..

I have a copy of the bible, so will look up the injector connections on the ECU wiring loom harness

Really appreciated folks:-)

[Steve_D]

Yellow/Blue ECU pin 13 odd cylinders
Yellow/White ECU pin 11 even cylinders

All 8 injectors get +12v from the same place but both pass through the 'loopback' connector (Blue) about 12" away from the ECU.

Steve