Hi guys, I bought an Audi A4 b6 1.9 tdi a few months ago. When I bought the car it drove fine, only issue being that the car would shake on a cold start for about 20 seconds. The shaking gradually got worse and now shakes a ridiculous amount along with a lot of white smoke. No engine lights are showing however a fault does come up on the diagnostic thing and it shows '4th cylinder miss fire'. I purchased an injector from a local scrapyard, had it fitted and still the same problem. The mechanic has now told me it needs a new engine but I'm hoping the problem can be solved without having to purchase a new engine. Any ideas?