2.5 TDI ACV: Engine Change After Filter Change

Hello everyone. I'm new here and unfortunately, I'm not an expert.
But I am desperate and I am asking for help/guidance.
My problem:
I replaced the fuel filter on my VW T4, 2.5 TDI / ACV, which has 400,000 km on it.
Unfortunately, I forgot to fill the new generator with diesel. After draining my battery trying to start it, I eventually managed to get it running by adding fuel to the filter.
Since then, I've had the feeling that one of the cylinders isn't working properly.
The car starts well. It doesn't smoke, and I can reach 155 km/h.
Here's what I've done so far: I've replaced the filters and all the hoses again. I've also replaced the fuel injectors, and the dual-mass flywheel (DMF) and clutch have been replaced.
The workshops say the engine is running well.
But I know my engine, and I can tell that it's not running as smoothly as it used to, and the power delivery is also weaker.
I own a VCDS, but I'm not really sure how to use it. There are no error codes stored in the control unit.
Could it be the ESP?
I certainly don't want to exchange this for a trial.
Could it be that the pump on one of the cylinders isn't working properly?
Please help me. Before I changed the fuel filter, the engine was running great, even with 400,000 miles on it.
I thank you in advance and I apologize, but I still need some assistance with VCDS.
Best regards, Markus.

Hello,

You have an axial piston distributor injection pump, which is essentially a rotating piston that performs reciprocating movements and injects fuel into the individual cylinders.

Normally, this type of fuel injection pump is very robust, and if there's a problem, it's highly likely that all cylinders would be affected.

If a single cylinder isn't running correctly, I'm more likely to suspect the problem lies within that specific cylinder rather than the fuel injection system. It wouldn't be the first time that a fault appears to be coincidentally related to maintenance work.

My advice would be to use VCDS to check the idle speed control and to consider having a compression test performed.

Given the mileage, it's highly likely that the fuel injectors are completely worn out.

For further assistance regarding VCDS and potential error causes, please refer to the search function.

Quote:

We cordially invite you to participate. The prerequisite for full access is... a diagnostic device from the Dieselschrauber Shop or our software KDataScope, KPower, or the Dieselschrauber license or an OBD support key. Dieselschrauber customers receive extended support (expert assistance) and full access.

Best regards, Rainer.

Thank you for the response.

The injectors were replaced.
I found information about idle speed control yesterday.
Unfortunately, it doesn't tell me much.
1 divided by 3 equals -1.41.
2 plus 3 equals -1.95.
4 divided by 3 equals -1.60.
5 to 3 = -0.68

Are the values suspicious?

Hello,

The sum of the deviations in the idle speed control system is 0.
That means the missing cylinder in your list has a very high positive value. Much more fuel needs to be injected there.

You can continue by submitting a support ticket.

Sure, here is the translation of the text from German to English:

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.