This is a JDM S5 Tii swap.

I was tracing the vacuum lines looking for something stupid that would explain why the engine won't run well. I noticed that this check valve came on the engine (I replaced all the OEM vacuum lines with silicone one-by-one in a very methodical manner). However, I dont see it on the vacuum diagram on FSM F2-7.



Is it necessary or appropriate?

Thanks,

jim