Originally Posted by J_Maher_WRX
What is this BPV sense hose issue you speak of? Please explain
Your BPV is the device that vents your intercooler depending on intake manifold pressure/vacuum. It bolts onto your intercooler, with the vent hole in the flanged base. The vacuum/pressure hose that tells it what to do connects to a nipple on the side. THE OTHER END of that hose, this sense hose, connects to a nipple on the rear bottom of the intake manifold under the intercooler. This nipple, like ALL the nipples on the plastic intake manifold, is a straight, non-barbed, slick plastic nipple... and all the hoses attached to it WILL blow off one day. When all but one of these hoses blow off... usually as a result of having been moved or under greater than stock boost... your car will become very unhappy. It throws a CEL and goes into limp mode.
To prevent the hoses from blowing off the best solution is to use a Corbin Clamp... Subaru uses them on the small overflow hose from the turbo coolant tank, for example. These clamps are the ones you pinch to open, slide onto the hose, put the hose back on the nipple, then slide that clamp onto the nipple portion of the hose. Some people zip-tie the hoses... these can and have failed as the zip-tie is not a dynamic clamp that adjusts to the aging hose. The Corbin style clamp is the permanent failsafe solution.
When you work on the engine you loosen these hoses because you move them. Thus, because installing the BP Mod requires removing the TMIC, the one inaccessible hose is disturbed and should be clamped. Even if you didn't do it then, it is still a good idea to clamp the numerous hoses attached to your intake manifold.
One hose, the Fuel Pressure Regulator sense hose, is far more problem if it comes off... if this hose blows off you will likely need a new engine. It is easy to get to, on the end of the IM on the driver's side. Clamp your hoses, and if you have a T in your boost control, do the same. All these hoses are thought of as "vacuum" hoses, but they also see boost.