2.0HDi sounds like pinking from engine

[PeteC8]

Hi again! Been doing one of my routine strange noise eliminations on my 2004 2.0HdDi auto. Sorted the long standing exhaust rattle out which now allows me to notice a slight intermittent pinking sound from the engine when hot, under load at lowish revs. Also does this model have a swirl valve?
Your expert advice requested please!

Edit: For clarification, by "pinking" I was referring to the tinkling sound that indicates pre-ignition in a petrol engine, never come across it in old school diesels but my knowledge of modern types is a bit scant.

[Rp0thejester]

Expert advice...well that counts out 99.999* of us. What do you mean by pinking? Is it a Barbie reference meaning all it does is moan?

[CitroJim]

Diesel engines, by their nature, sound like they are on the edge of pinking with their characteristic 'diesel knock' but this should never sound 'tinkly' and/or metallic.

It sounds like it's running a little over-advanced... A Lexia session would be valuable to determine if this is so and one cause may be the temperature sensor - if it's duff the ECU may hold the belief the engine is always stone-cold and apply cold-start advance...

That's just a hunch. A Lexia, I'm sure will offer a better insight.

Another cause may be poor spray patterns from the injectors. Is is at all smokey? Possibly yet another cause may be the MAF sensor as I've known these engines run a bit roughly with a tendency to produce a greater than normal level of diesel knock.

As far as I know, these don't have a swirl valve but I can't be certain. My belief is they were only on the 2.2.

[PeteC8]

Diesel engines, by their nature, sound like they are on the edge of pinking with their characteristic 'diesel knock' but this should never sound 'tinkly' and/or metallic.

It sounds like it's running a little over-advanced... A Lexia session would be valuable to determine if this is so and one cause may be the temperature sensor - if it's duff the ECU may hold the belief the engine is always stone-cold and apply cold-start advance...

That's just a hunch. A Lexia, I'm sure will offer a better insight.

Another cause may be poor spray patterns from the injectors. Is is at all smokey? Possibly yet another cause may be the MAF sensor as I've known these engines run a bit roughly with a tendency to produce a greater than normal level of diesel knock.

As far as I know, these don't have a swirl valve but I can't be certain. My belief is they were only on the 2.2.

Sir, you are worth every penny that the FCF pay you!!

I too understood that to be the case regarding the swirl valve, having hunted vigorously and not seen any sign of it, just threw that out as IF there were one and it was duff then it could have possibly upset the fuelling. Well aware of the rattle of over advance, having delved into many classic diesels, but as I said, these new-fangled things are something else!!
Doesn't appear to be smoky and was absolutely clean for the MOT 3 months back.

Doesn't run at all rough and I cleaned up the MAF sensor for the MOT as a precautionary step

As it didn't use to tinkle your comments are heading me towards spray pattern, guess a good start will be to run some cleaner through it. Also the temperature sensor advance sounds a good one to pursue!

It may sound like I know all the answers, please be assured this is not the case, I am open to all leads such as you have given me. I had the vaguest of ideas that I had seen someone mention some sensor or other that may give a tinkling rather than rattling effect, but it wasn't a problem I had at the time!!

Anyway many thanks for your invaluable assistance, end of essay so far!

[CitroJim]

I'll be following this with interest Pete, to see what the cause is

Do you have a Lexia or a member living nearby with one? That may also help to see if one or more injectors are misbehaving...

[PeteC8]

I'll be following this with interest Pete, to see what the cause is

Do you have a Lexia or a member living nearby with one? That may also help to see if one or more injectors are misbehaving...

There are, I believe, members nearish, initially I will pursue the simple under bonnet bits rather than trouble them, then report back.
Thanks again for the pointers!

[Leebroath]

Sounding like the same what I hear from my 2020 Audi SQ5, but have had the same ‘tinkling noise’ on my old Saxo VTR, my Audi A7 and now SQ5, and have NEVER got to the correct answer.

Through trying to establish the root cause of my Diesel Audi SQ5 and its ‘tinkling’ I’ve stumbled across this forum and many others. I myself just can’t find the correct answer, and having been back and forth with Audi all I’m getting now is it’s a ‘characteristic’ of the car, which I’m not believing.

Ive had many, many suggestions like Injection deviation, fuel ratio, use a higher octane, its Injector…the list goes on

Audi even replaced a front exhaust pipe, thinking that would stop the tinkling noise, which it didn’t.

To advise what it sounds like, one person hit the nail on the head. It‘s like someone dropping screws into a glass jar, which is much like the noise when accelerating in low revs/load. We hear it more when windows are down during summer and especially going through a tunnel or driving beside a wall as the sound echo’s back and is clearly heard.

I am at my wits end with this noise, and for some reason trailing through mountains of videos, not one person seems to have this recorded..

It’s not the ‘knock‘ as some people say, mostly all videos are from cars sitting stationary, with camera looking at engine bay, but nothing while car is driving and the tinkling can be heard.

Would buying a good OBD2 Scanner and plugging it in help? Was looking at the Autophix 7610, and looking at sending some Powerenhancer premium pure 2-EHN Octane Booster into the fuel tank to test?

[PeteC8]

I've learnt to just live with it now, keep hearing other "modern" diesels going past making similar noise, quite possibly aggravated by the modern fuel combined with hyper critical injection sequencing. Good luck with your search!

[Rp0thejester]

I'm wondering if it's the sound of carbon deposits being burnt off, I can't think of anything else that would sound like screws dropping into a glass jar.

[PeteC8]

Just living with it. Definitely some complaint from the mechanical horse, but doesn't seem to get any worse. May even be a little added water injection from a cracked head (always looking on the bright side!).

[Paul-R]

... and looking at sending some Powerenhancer premium pure 2-EHN Octane Booster into the fuel tank to test?

You don't have an octane rating for diesel, it's a term used for petrol. Diesel uses cetane rating to indicate its quality.

[RichardW]

The original 2.0 HDi in 90 BHP guise used to suffer from a rattle below 3000 rpm as the injectors aged. Thought to be due to a slight dribble from the injectors on the pre injection phase - it was noticeable that it cut out when you got to 3000 rpm as the pre injection was cut off. Think the C8 engine is a bit different with a 16v head, but it may be similar injection strategy.

[PeterM58]

Hi, I just joined this forum to share my experiences regarding this pinking noise. I drive a 2009 Citroën C5 with the 2.0 HDI engine. Symptoms were:
- no noise when cold
- when warm, pinking noise when accelerating with a light load, no noise when accelerating hard
- pinking noise sometimes absent for an period of time, but always returning...
- during the pinking a loss of power
- otherwise running fine

Changed fuel filter, checked injectors, all fine.
It turned out to be the fuel pressure control valve (régulateur pression gasoil). It was replaced by my (French) garage at a cost of 300 euros (160 for the regulator, 140 labour). I have driven now a couple of weeks with no pinking noises. So I guess it is fixed.