R56 Cold Start sputtering, runs fine, no codes.

[djkraus]

Hi Everyone, Hoping for some insight into my 2010 Cooper S cold start issues. Usually the car starts and runs fine but every few starts I can tell it is starting to sputter and I shut it off right away. It then starts and runs fine. There are no codes. When I read the live data everything looks normal. The fuel pressure sits at 725psi which is exactly what is called for. All air pressure and temperatures look normal. My biggest suspect now is a fuel injector leaking into the cylinder. As soon as i turn off the engine the fuel rail pressure drops drastically. Does anyone know how long a properly functioning fuel system will hold pressure?