V6 TDI: Intermittent Idle Misfire - Diagnosis

Hello everyone,

After a long time, I'm back with the diesel mechanics, and I immediately have a problem .

'I've been concerned about a problem for some time now. When the engine is idling, there's an irregular, soft vibration that feels like a kind of twitching. However, it's not a hard misfire...'
Otherwise, it starts perfectly well, both when cold and when warm, and in my opinion, there is no noticeable loss of performance. Also, there is no noticeable jerking or hesitation while driving.

Does anyone have a tip or have they experienced this problem before?

What should I check beforehand, or what information can you provide to help me read the MWB (Material Safety Data Sheet)?


First of all, a big thank you to everyone who posted!

Regards,

DENNIS

Manual or automatic? If manual, possibly a single-mass flywheel.

How many kilometers?

Sorry, I completely forgot in the 'excitement' .

It's a switch and it has 156,000 kilometers on it.

The 'jerking' occurs both when the engine is warm and when it's cold, and it's also independent of the outside temperature.


Regards,
DENNIS

GarfieldMZ wrote:

The "shaking" occurs both in warm and cold conditions.

Does it change slightly with temperature changes? For example, does it become weaker when it gets warmer?

Do you have VAG-COM?

I need to observe how well it performs in extremely cold conditions.
is in a warm operating state.

Yes, I have VAG-COM.

GarfieldMZ wrote:

Yes, I have VAG-COM

.
Have you ever checked the idle speed control?

Yes, it wasn't noticeable... but I completely forgot to turn off the climate control and other settings.

I'll check that again tomorrow and post the values here.

GarfieldMZ wrote:

I completely forgot to turn off the climate control and other settings.

That doesn't matter. He should also have a decent idle speed with the climate control on, right?

yes, of course...

I just read somewhere that all appliances should be turned off during an inspection.

Could a hydraulic lifter also be a possible alternative to fuel injection?

GarfieldMZ wrote:

Could a hydraulic lifter also be a possible alternative to fuel injection in some cases?

It's rather unlikely. Is the engine making a knocking sound, or how did you come to that conclusion?

As I mentioned before, it might not be coming from the engine itself. A dual-mass flywheel (ZMS) can also fail and cause similar issues.

I just read something in one of the posts here that suggested it might also be a hydro.
With 24 pieces, the chance isn't exactly small .
You can't actually hear anything. But with the noise level when the hood is open, it's also very difficult to distinguish any specific sound!

Hello everyone,

I need to revisit this issue because the cause still hasn't been identified.
I admit that I haven't been following it closely in the past few months either. Perhaps even more problems have arisen, or new ones have been added.

One thing you can hear is a very faint ticking sound when the engine is idling. Some people say it's the fuel injector, while others say it's the lifters.
'Additionally, I've noticed for the past few weeks that the engine sometimes runs louder during the warm-up phase. You might not necessarily notice it in the performance, but you can hear a more pronounced knocking sound when accelerating. However, this usually disappears after 1-2 minutes of city driving and hasn't reappeared since (so far).'
'Thirdly, two weeks ago, while I was driving on a country road and accelerating hard uphill after a curve, I experienced a 'soft' loss of power, which then subsided just as 'softly' after 1-2 seconds. This happened again shortly after, but not since then.'

Does anyone have any idea if all of this is related, or if we're just going to keep encountering more and more problems?
'Is it opening? I now have almost exactly 200,000 km on the odometer, which shouldn't really be a problem, right?'

Thank you all!

DENNIS

Okay, FS, I'm assuming you've already reviewed the material.
I can actually confirm that "nagging" sound when accelerating in cold conditions, and I would consider it normal for the 2.5 V6 TDI engines.
However, your NHG (National Health Insurance) might already be causing problems.

What do engine mounts with map-based control look like?
Is the red soup already running out?

Furthermore, I would remove both valve covers and check if all the valve springs are in good condition, or if they have any play or cracks.

Could the slight loss of power be related to the ESP (Electronic Stability Program)?
Otherwise, the fault code "Intake manifold vacuum control limit exceeded/fallen below" would likely appear in the diagnostic system.

Yes, the flash storage is read and empty. There were no errors detected.

As far as I've noticed so far, the knocking sound always occurs within a very specific range of the warm-up phase and only lasts for 1-2 minutes. It sounds like the injection timing might be slightly too early.

I haven't checked on the soup yet, but I will do so. There's nothing saved in the FS.

Before removing the lid, I'm a little apprehensive. Not just because of the work involved, but also because of the difficulty in getting the lid back on and what one might expect to find underneath.

I don't think it was the ESP, because it would have surely indicated the problem with a flashing warning light? I once managed to get the ESP light to flash while driving with the Quattro.

Quote:

It always occurs within a very specific range of the warm-up phase and only lasts for 1-2 minutes.

Perhaps there's a software update available, have you checked?

Best regards, Rainer.