BMW E46 320d - 110 kW/150 HP - 12/2002 - Engine stall and abrupt RPM stops/shocks

[N00B3R]

Hello,

Since a few days I have been having issues with my BMW 320d year 12/2002.
It started out as a light "tonk" sound, the sound of metal on metal, I have no idea how to describe it better.
You could hear it every now and then, especially when idle and when the engine is warm. The RPM's drop for a splitsecond and then the motor keeps on running like nothing happens, then a few seconds later the same thing happens.
The RPM drops at the same time as the metal sound you can hear.
Lately it gets worse and worse, I managed to bring the car home and I think I can make it to the workshop too (already made an appointment).
I had no engine stalls up till now, today, the engine was shocking (again, as seen on the video) and then suddenly stalled when idling at a red light.
I restarted the car again and it fired up without hesitation, the sound still persisted.
Furthermore, I noticed a sudden power loss when the shocks happen (they happen infrequently and they don't take long) but the car keeps running.
I did not try flooring it to see where I can take it because I'm very scared that I will screw up my engine block, then I'm in some real trouble since I can't afford a new car at this time (and an engine rebuild is pointless for such an old car).
You can hear the sound on the video in the beginning and once at the end.



Extra info:

- There has no work been done on the engine, except for the removal of swirl flaps and replacing them by blanks, that was done a few months ago
- At the same time of the removal of swirl flaps, we changed all filters (air, interior as well as dieselfilter)
- I have noticed that the clicking sound also happens when I go into RPM's higher than 2000, but I'm not really sure, it could just be an illusion.
- Yesterday, the DDE light came on when I drove the car, I noticed the engine being a lot louder too, also it seemed to me that all of a sudden, the car got a boost when I pull up.
When I parked the car, I started it again and the DDE light still came on and stayed on. However, this morning, I used the car and the lights were off, even when the engine stalled a few hours ago at that red light, there were no warning icons lit up.

If any of you know what this is or could be, I'd be grateful. I myself don't know a lot about cars, I just want to make sure that my mechanic got it right and doesn't give up and tries to sell me a new engine block for nothing.

Thanks in advance for your time.

[N00B3R]

Anyone that can help me out with some tips or suggestions?
This item is time sensitive since I'm sitting without a car and thus without work at this very moment...

[N00B3R]

Guess I have a really unique problem then lol, I'll wait for the mechanic to tell me what's wrong, then report back here.
In the meantime, if anyone knows what it could be, let me know

[N00B3R]

Update:

The car has been with the mechanic for a few days already, I told him to use the car whenever he needs to go do something to reproduce the sound but he can't manage to make it happen.
He has been driving the car for 30 minutes and switched between high and low RPM's but the sound does not come back.
He had a rail pressure error which on reset, did not come back (he did not replace anything at all).
How is this even possible? I don't want him to give me the car back and tell me that it's nothing if it will happen again in a week or so. (You can hear that it does not sound well)

Found a few videos that display the same issues (it's not the same car though):

https://www.youtube.com/watch?v=Fm44GEvIWK4
https://www.youtube.com/watch?v=40XGxGoiFzA
https://www.youtube.com/watch?v=yYm73UnfNDw

[N00B3R]

I've got my car back, they drove with it for a week and used it as they would with their own car, they were not able to replicate the sound issue.
Any one of you got an idea of what this might be? The sound has disappeared, I drove with it myself for an hour straight and changed high and low RPM's and nothing...

[Honolulu]

The "problem" here is that few of us here in the USA are familiar with the workings of a diesel engine, much less a modern computer controlled engine such as in your car. I realize that this is an international forum (obviously, since you're here) but on a large scale, much of the membership is oriented to gasoline vehicles.

Sorry I can't be more helpful, but if the shop kept your car a week, could not "fix" it, and put significant mileage on it, it's time to find another shop that respects their customers a little more than that one. Still if the noise and stalling has disappeared, go with that and be happy.

[N00B3R]

The "problem" here is that few of us here in the USA are familiar with the workings of a diesel engine, much less a modern computer controlled engine such as in your car. I realize that this is an international forum (obviously, since you're here) but on a large scale, much of the membership is oriented to gasoline vehicles.

Sorry I can't be more helpful, but if the shop kept your car a week, could not "fix" it, and put significant mileage on it, it's time to find another shop that respects their customers a little more than that one. Still if the noise and stalling has disappeared, go with that and be happy.

Hmm, I get that, but since my topic probably reaches a good amount of people, you never know who has the right answer. Also, some things are the same whether it is a gasoline or diesel engine. But I get your point.
Anyways, to update this thread: my mechanic has read out an error with the Rail Pressure Sensor (electrical malfunction) and asked Autologic (the company that created his diagnostic tools) what he had to do. They said to start with replacing the Rail Pressure Sensor, it is uncommon for it to fail, but since the code displayed an electrical error coming from that sensor, they are pretty sure a replacement would fix it. It set me back about $ 350,-.
Currently, I have no further issues, I noticed that the problems start happening when you drive over a bump or shake the car a bit when driving, it's as if something was loose (maybe it was a connection on the sensor).
We'll see how it goes, just drove a half hour at 120 km/h without any issues, also passed some bumps and took them intentionally hard to see if the problem comes back. It didn't.
Now a rear tail light error comes up once in a while whilst I replaced the entire block and connectors a few months ago, the hell is this. It seems that every time I spend money and fixed something, a new issue pops up

[metale]

I'm getting one of those soon, may be able to provide some feedback later.

On the meantime drive it some more.