In regards to check vales....I have a JDM FD3S twin turbo and I recently changed the alternator. Whilst doing this I noticed the the pressure chamber had no hoses going to them. I managed to trace them back and all that which was fine, but ever since I changed the alternator and noticed them hoses came off (must of fell off whilst getting the chamber off) the car idles wayyyy too high. Now, looking into it more and more and looking at the diagrams for vacuum hoses for the "rats nest" I noticed the inlet hose for the pressure chamber doesn't have a "check valve". Could this be the issue due to its high idle?? because there is no vacuum leaks.

Thanks for your time.

 

Intuitively yes. Even after all these years the sequential system still confuses me, but seems like not having that check valve would mean you do, in fact, have a vacuum leak.

FWIW, a member here named DaleClark sells Viton check valves that are superior to the OEM version. In addition to the Viton diaphrams, they have barbed ends and much sturdier valve bodies. Not sure if he ships internationally, but might be worth a Private Message. They aren't expensive...last I knew about $20 U.S. for a set of 5.

 

Dale clark did some good write ups with swapping the lines and what not. Stumbled onto them while searching for boost issues