3.0i M54 Rough idle then cuts out

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Martin/Stuart et al. I really enjoy reading the posts. I just wish I understood what they were all about, especially all those acronyms. I hope Wednesday is a better day weather wise than today and that all goes well.

Cheers.
Acronym is easy. DME is the ECU for the engine.

Thanks Martin. Every day is a school day. Joking apart. It is impressive to see the range of knowledge and expertise available on the Forum. Imagine what the cost would be if you had seek help from a main dealer.

More cost and probably less idea

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Well I have bad news dammit!
Despite Stuart's best endeavours we cannot fix this motor.
I managed to reproduce the fact that it runs perfectly for a few seconds when you reset the faults and we are in full agreement that it is the DME. Cannot feasibly be a mechanical problem or why would it run so cleanly when you reset the electrical gubbins?
However, INPA could not even see the DME, let alone find out its software version or attempt a reflash. As far as it was concerned there was no DME in the car!
Interestingly, while we tinkering around, every minute or two we heard a click from somewhere in the locality of the DME and the fuel pump would run for a couple of seconds.

Anyway, I have invested a fair bit of time and materials into this car now so I'm not willing to break it just yet.
Next step is get the DME out and send it off to either be repaired or cloned.

Watch this space.

[Chris_D]

Before you quit, like a big fat quitter eating a melted slice of quit, have you tried swapping/replacing the fuel pump relay?

[enuff_zed]

Before you quit, like a big fat quitter eating a melted slice of quit, have you tried swapping/replacing the fuel pump relay?

Not yet, but why would that reset when I clear the codes? And we can hear the pump running too.

[Chris_D]

Before you quit, like a big fat quitter eating a melted slice of quit, have you tried swapping/replacing the fuel pump relay?

Not yet, but why would that reset when I clear the codes? And we can hear the pump running too.

Who knows?
But it's worth a look and easy enough to check isn't it?

[enuff_zed]

Before you quit, like a big fat quitter eating a melted slice of quit, have you tried swapping/replacing the fuel pump relay?

Not yet, but why would that reset when I clear the codes? And we can hear the pump running too.

Who knows?
But it's worth a look and easy enough to check isn't it?

Never rule anything out.

[Rix]

Well I have bad news dammit!
Despite Stuart's best endeavours we cannot fix this motor.
I managed to reproduce the fact that it runs perfectly for a few seconds when you reset the faults and we are in full agreement that it is the DME. Cannot feasibly be a mechanical problem or why would it run so cleanly when you reset the electrical gubbins?
However, INPA could not even see the DME, let alone find out its software version or attempt a reflash. As far as it was concerned there was no DME in the car!
Interestingly, while we tinkering around, every minute or two we heard a click from somewhere in the locality of the DME and the fuel pump would run for a couple of seconds.

Anyway, I have invested a fair bit of time and materials into this car now so I'm not willing to break it just yet.
Next step is get the DME out and send it off to either be repaired or cloned.

Watch this space.

Thanks for the update - disappointing but another bit of investigating compete. Weirdly I have the same issue insofar as my cheap code reader cannot see the DME and wondering whether to get mine sent away. I opened mine up at the weekend and couldn't see anything physically damaged in it. I multimeter tested the mosfets which seemed ok but that was the end of my technical skills! Have you got somewhere in mind for where to try to get it repaired? https://www.actronics.co.uk/ get recommended on the UK salvage YT channel but they seem to only deal with the trade.

Edit, I also checked the fuel pump relay (behind the fuse box) and the two relays in the DME box - I think one does the DME itself, and also jumpered the relays to see if that helped. Still no start at all for me!

[enuff_zed]

Well I have bad news dammit!
Despite Stuart's best endeavours we cannot fix this motor.
I managed to reproduce the fact that it runs perfectly for a few seconds when you reset the faults and we are in full agreement that it is the DME. Cannot feasibly be a mechanical problem or why would it run so cleanly when you reset the electrical gubbins?
However, INPA could not even see the DME, let alone find out its software version or attempt a reflash. As far as it was concerned there was no DME in the car!
Interestingly, while we tinkering around, every minute or two we heard a click from somewhere in the locality of the DME and the fuel pump would run for a couple of seconds.

Anyway, I have invested a fair bit of time and materials into this car now so I'm not willing to break it just yet.
Next step is get the DME out and send it off to either be repaired or cloned.

Watch this space.

Thanks for the update - disappointing but another bit of investigating compete. Weirdly I have the same issue insofar as my cheap code reader cannot see the DME and wondering whether to get mine sent away. I opened mine up at the weekend and couldn't see anything physically damaged in it. I multimeter tested the mosfets which seemed ok but that was the end of my technical skills! Have you got somewhere in mind for where to try to get it repaired? https://www.actronics.co.uk/ get recommended on the UK salvage YT channel but they seem to only deal with the trade.

Sent a few queries to some of the companies that advertise repairs etc. I'll see what comes back.
Have already, through the wonders of the forum, found a replacement DME should I need it.
Very interested in the suggestion that you can disable the vin-specific parts and simply 'plug and play'. Something that bigwinn is looking at more closely.
You need to x-ref to this thread too for the full discussion:
viewtopic.php?t=133520

If you can hang on a bit with yours we may get some more answers for you.

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Mostly for Rix's benefit, as I know you're waiting; this is where we're at.
I stuck the DME Part Number into Realoem and found a long list of retrospectively exchangeable ones.
Barry (umfaan had one and it is currently on it's way to me.
Stuart (bigwinn, via the other thread I linked to, has found and downloaded some software. We are reliably informed that we can put the replacement DME into the car, locate and disable the bit that runs a check with the EWS system and then it will function perfectly well in my car, probably with a reflash to ensure it is all up to date and working properly.
I think I have now exhausted every other possibility, including the hopeful straw-grabbing ones so the only step remaining after this is to throw some money in the direction of Mr Esso and Mr Swan Vesta and hope that sorts it.

[Rix]

Thanks for the update and yeah I hope so too! If it turns out to be the DME I'm not sure if that makes me happy or not, but obviously it would be great to have it running - both you and me alike!

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Had another visit from bigwinn today, armed with his newly acquired software. The theory being that we could fit a compatible DME and simply tell it to ignore the EWS and it would work.
Well, not quite!
New DME fitted and the software found it and all seemed to be going well. However, the check box to disconnect the EWS would not light up as advertised. Tried to fire it up and we still got a whole raft of codes and it wouldn't even start.
So then we noted that we could update the VIN. The DME has 14 slots to put a VIN into. Unfortunately, you can add, but you cannot remove the old one.
We added my car's VIN and when we updated it, sure enough the DME now shows my VIN. Partial success at least and something Stuart can hopefully use in the future.
Now when we checked it would still not start!!!
All the warning lights are out and the only code is a tamper warning for the EWS. (Even though it should be seeing the correct VIN). Car locks, unlocks, alarms etc, so it seems to be a communication issues between the DME and EWS.
Still we cannot access the check box to disable that function.
Out of interest we refitted my old DME. That starts, hunts, eventually dies, resets and runs smoothly for 10 seconds then dies again. Exactly as it did before. Stuart tried to interrogate it but the new software cannot find it - which at least seems to isolate the issue to that DME.
So it at least seems to prove the EWS is not at fault as that recognises the DME and lets the car start.

So where are we now? Stuart ran out of time so he's gone away for a think and to speak to the chap who supplied the software. Pretty sure if we can just sever that check between DME and EWS we'll be winning.

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Stuart came back this morning. That's 3 return trips from Lincoln to Attleborough for which I owe him big time!
Having sussed out the software issue using his own car he was brimming with confidence.
First pass didn't work but I think that was mostly due to the sun shining on the laptop screen and a check box being missed.
As the process takes about 20 minutes we decided it would be safer to then connect up the battery charger.
Tried again and the software couldn't see the DME!!! WTF?
Tried INPA and it couldn't talk to the car at all.
Much head scratching ensued. I was halfway to fetching my wallet for the fuel and matches when I had a moment of inspiration.
Disconnected the charger and it all worked fine. No idea why, but worth bearing in mind for anyone else doing this kind of stuff.
10 minutes later a purring engine, a smug Stuart and a very relieved me.
Rix, I reckon Stuart is going to be ready to sort yours pretty soon if you get in touch with him.

What a relief! The old 'Cheapskate' is still going strong.

[inkey$]

Seems like all that hard work paid off. Result!

[IRD]

Very impressive Martin/Stuart. Great result.

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Very impressive Martin/Stuart. Great result.

Well Stuart really. It was he who bought the software and drove miles to help out. I made tea and became adept at swapping DMEs that's all.
Great satisfaction at tracking it down though. I enjoyed the logic involved and the elation when it fired straight up and purred was great.
I'm hoping this is one of those investigative threads that can help others as our cars get older and the electronics start to play up.
We will certainly be saving DMEs now and I'm pretty sure Stuart will be doing a few more of these.