I have a A4, 2008 mod. It has just a little power when starting, white smoke and in the beginning of driving. I have new turbo serpent, top cover gasket, fuel injector wire harness and new turbo. Its still not working properly.Lately the sign of glow plugs shows. Disapears when turning engine off and on. Multiple diagnosis, no error. The car workshops has given it up. Anyone with ideas ?