[alex492]

So I've had the jb4 installed on my 2008 335xi since about march of 2013 and never had any troubles until this winter. Whenever turn on the map (map 2 because I have downpipes) and floor it from a stop, it jerks at about 5000rpm in first and then in 2nd it loses all power and the service engine soon light comes on. So when this happened I immediately stopped the car and had it in idle and it ran extremely rough making weird noises. I then turned off the car and turned it back on again and it was fine. But same thing keeps happening when I floor from 1st to 2nd, loses power and light comes on.

Does anyone know whats wrong?