2.0 TDI BKD: Severe Engine Misfire During Acceleration

Hello,


Here are some details about the car:

Octavia 1Z 2.0 TDI
BKD
248,000 km
Modified loader.
Chip tuning.
AGR closed/discontinued.
Head replaced less than 2000 km ago.
Vintage, common.


"For about 1000 kilometers now, it hasn't been delivering its usual power above 3000 RPM and is struggling to reach higher speeds."
Yesterday, it suddenly started shaking very violently when accelerating in every gear, especially in the higher gears.
It gets better above 3000 RPM.
It produced a significant amount of soot, but it wasn't deep black; rather, it was somewhat lighter in color.

Two spark plugs showed up in the car's diagnostic scan, but they no longer appear after clearing the error codes.

I have attached the PDF documents.

Unfortunately, I'm a bit at a loss right now.

It starts up very well and idles very smoothly.

Processed loader.
Chip tuning.


That's where I would start.

Where the deviation of 3.xx mg/r is not really ideal .

mullemaus wrote:

Quote: Processed loader. Chip tuning . That's where I would start. Where the deviation of 3.xx mg/r is not really ideal

.

The software has been installed for quite some time now, even before I bought the car, probably around 20,000 km or more, and so far there have been no issues.

If the engine's hardware – compression, camshaft, and lifters – is all in good condition...
My suggestion is that the problem might be related to leaky pressure diaphragms (PDs).

... I had the same problem last year with a Touran that also had a BKD engine.

Fuel filter changed?

Hello,


PDs habe ich beim Kopfwechsel neu abgedichtet, oder meinst du intern, quasi das eins (ich vermute das am 2. Cylinder) Dripping?

The diesel filter was replaced once, but not recently; it was about 25,000 kilometers ago.

Quote:

PDs habe ich beim Kopfwechsel neu abgedichtet, oder meinst du intern, quasi das eins (ich vermute das am 2. Cylinder) Dripping?

I read that, but I would only be sure if I had done it myself.

If this defect did not exist before the change in the central system (ZK), or if the peripheral devices (PDs) are still the old ones, then...
I personally...

Expand.
-- have it checked, if not already done, and/or...
-- replace the seals and reinstall them. I would also swap the pressure dividers among themselves.
Specifically, swap the functions of both inner pressure sensors (PDs), so that cylinder 2+3 are connected to cylinders 1+4 and vice versa. If the error persists, you can draw conclusions based on the LL (likely referring to a control or regulation system) behavior: observe whether the error values or positive/negative readings shift with the swap.

I am not making any promises that would constitute a cause for action; in fact, I explicitly disavow such a commitment.

Perhaps someone else has other realistic suggestions.

The software has been there for quite some time now, even before I bought the car, probably over 20,000 km or more, and so far without any problems.

That's great, but unfortunately, it's completely irrelevant.
These 'modifications' are probably not reliable; the first time they're really stressed, they'll likely break in a funny way.


New head installed 2000 km ago .




It's always interesting to know the origin of the parts, and whether, for example, the PDE (pressure drop element) has been modified. When using a larger, sorry 'modified turbocharger,' the standard injectors are at their limit.

And, if the head has been replaced, the PDE seals were re-sealed. For simplicity's sake, it's best to talk to the workshop; something might have gone wrong.

Just for the record,
What was the engine temperature before the test drive? LLR values are not very informative when the engine is cold. The ignition timing is too advanced.
hg
Herbert.

It's always there.

Sure, I will translate the text from German to English and provide only the translation without any explanations. Please provide the text you would like me to translate.


Description: PD values after a short drive (water temperature at 90 degrees)

Nö, bei den Werten "vor kurzer Probefahrt" nicht. What is short?
Believing is not the same as knowing.
hg
Herbert.

What do the values in the MWB 23 look like?

Is the mixing tube installed in the new control unit?

-> http://mam.kspg.com/mc/epaper?guid=14c1446b91dfb82c

I don't know what the values are in the MWB23 system, but I have a feeling that the car warmed up extremely quickly, or that the temperature gauge rose to 90 degrees very rapidly.

Yes, the mixing pipe is new.

I've now purchased a PD element and will test it in the coming days to see if any of the previous ones were defective.

KvD wrote:

I don't know what the values in the MWB23 are, but I have a feeling that the car got extremely hot very quickly, or that the temperature gauge rose to 90 degrees extremely quickly. Yes, the mixing pipe is new. I have now purchased a PD element and will test it in the coming days to see if any of them were defective.

Hmm, a rapid increase in temperature could indicate a faulty water pump impeller! Does it overheat when you drive above 130 km/h?

Error found...

I didn't replace the tensioners after the timing belt broke, a big mistake...

Lucky me, and thank you for the feedback .