Originally Posted by Gugs
The answer is-
Your overboosting or knocking.
With the newer firmwares we have new features...
The Jb4 goes into safety mode and forces itself into map 4 until you restart the car.
look for flashing check engine lights right before it happens, 1 flash is overboost and several is knock.
This is exactly what is happening-
as its defaulting to map 4 and leaving you to OEM map/boost levels.
Put in less e85 and it will most likely help the issue.
Yup. The JB4 reverts to stock mapping as a safety feature. The stock boost for a 335is is 10psi.