Audi A4 B8 2.0 TDI 2011: Engine Starts Then Shuts Off - Possible Reasons?

Hello, I have an Audi a4 B8 2.0 TDI and I have a problem with starting the Zapała engine and after a few seconds it goes out, which may be the reason for this engine behavior. There are no bugs on the vagu

There may be many reasons for this.
Diagnostics, viewing parameters.

the car will start after a few attempts?

Vag connects to this car? How do you diagnose it?

Returning to the topic, the engine fires and goes out, it's simple, you need to clear the exhaust outlet (burn out the catalyst)
I did the first, I dismantled the catalyst and it was under pressure with my mind, then mounting, which is a bit of a problem because there is little space, but you have to be persistent and then detach and keep it at revolutions to about 2000 until it stops smoking, it takes about 15 - 20 minutes ? the color of the smoke is blue turning into black and then in the whole there is no smoke and finito greetings, constant