How to Read: A Beginner's Guide

Aloha everyone!
Next weekend, the timing belt (on the car ) will be replaced, and the last fuel injector (with NBF) will be replaced with a calibrated one (which worked well with Henzo).
Now, a very skilled mechanic is going to do the ZR swap, with information provided by a VW specialist.
I haven't yet understood why certain things need to be done after replacing the nozzles...
But the question is: what can, should, or can one reasonably expect to be read out when trying to ascertain the overall health of the engine/pump/electronics? The error memory is clear; I don't expect anything there because everything is okay. I'm more interested in a few terms like idle injection quantity, injection timing, and so on. What should be queried, and where do I need to be careful that someone is just trying to talk me out of something? After the last bad experience with the Bosch service, I'm very distrustful.


Best regards,
Torsten.

Good evening.

Hopefully, your VW mechanic is as knowledgeable as your trusted Bosch service center .

What is supposed to read out? Most of them can't even properly interpret the data (most are just happy if they can even find the diagnostic port ). You can read out data until the interface smokes, but it doesn't achieve anything.
I would spontaneously suggest checking the idle speed control. With new injectors, the values should definitely be below 1.00 (or significantly below) and not deviate too much from each other.

What questions should I be prepared for, and where should I be careful to make sure someone is just trying to talk me out of something. After my last bad experience with the Bosch service, I'm quite suspicious.
To bombard you with technical jargon without you having the necessary background knowledge, in my opinion, is not very helpful. I would rather recommend you the 'fun pocket guide' for diesel enthusiasts from Bosch. After that, you won't be easily misled . I think this was also mentioned in another thread.

Thank you, Arno.
That's already a good tip. The fun little book is certainly very helpful, but generally speaking, it can't be that everyone has to learn everything themselves.
Ultimately, we live in a society with a division of labor .
For me, I'm looking for someone who can help me with these things, specifically someone familiar with KN or AA, or something in between. And if I have to somehow gather the knowledge and hardware first .
Impossible

Best regards,
Torsten.