Touran 1.9tdi pd105 only starts without oil cap

[P34chy]

Hi, I'm having problems with my Touran, a few days ago it cut out while driving and had to roll to a lay by. Couldn't get it started and run the battery down. AA attended and attempted to jump start but no luck and was towed home.
Anyway after attempting a few things, the car will start if the oil cap is removed but as soon as it's put on again, it cuts out.
I'm trying not to send it to a garage and don't want to buy anything that will be a waste of money and thought there might be an answer here somewhere, please help

[VAG-Abound]

Read your other post about nothing coming out of exhaust. Not even with oil cap off? Any sign of where exhaust is then going?

My first thought is stuck turbo blocking exhaust manifold. What engine code? Model year? Warning lamps? Error code scan?

[Hannu5]

Check the egr to see if it's blocked or held open.

It recirculates the exhaust gas by diverting into the inlet manifold and should remain closed during starting and Slow running. It may not fire if it's fully open, just kind of "chuff" as you try.

You could check by removing the air filter and try starting it, check to see if you get prominent exhaust gas present in the filter box.