Hello. New here and my dad just bought this T100. I am doing the tune up and changing old stuff out (old headers) and I noticed there is cap on a vacuum hole please see pic. I am dealing with lean condition wondering if this hoes needs to be routed somewhere.

 

My JDM 3.4 runs the fuel pressure regulator off that port. You might check that the pressure regulator is hooked up to another vacuum source, if not that could be a part of the problem.

 

thank you. I will check tonight.