Swapping in an SR20 into your S-chassis? Here’s a diagram, it’s wonderfully simple as long as you don’t care about passing smog. There are only 3 vaccum lines that are absolutely necessary. Most mildly modified SR20′s will have 4-6 depending on what extras are added on. Lets begin.
The throttle body has 3 vaccum sources coming off of it. Two above the throttle plate, and one below. The top left vaccum source is for the fuel pressure regulator. Also, if running a boost gauge (like you should), you will need to T off of this source to get the boost gauge signal. The top right vaccum source is for the Recirculating or Atmospheric Blow Off Valve. Lastly, the bottom left vaccum source is for the carbon canister. However, a lot of SR swaps will have this capped off because not having it isn’t going to make us fail emissions. We fail anyways! The large hose above the throttle body that connects to the intercooler cold pipe is for the idle. Please hook it up; your SR will thank you.
The wastegate gets it’s signal off of the charge piping (aka Intercooler Piping). The stock piping has has a nipple on the cold side for the wastegate. Blitz and HKS front mount kits have a nipple on the hot side, and GReddy or custom intercooler kit will need to have a nipple welded in on the hotpipe (or somewhere else on the charge piping). If you are going to run any sort of boost controller, the boost controller needs to sit in the “middle” of this vaccum source. Meaning that you will need to have the nipple on the charge piping go to the “In” side on the boost controller, and the “Out” side needs to go the wastegate actuator. I don’t have a boost controller on mine, thus I run a vaccum source directly from the charge piping to the wastegate.
This oddity sits on the ignitor chip plate. If you got a clip, yours was probably hooked up. Well… you don’t need it when you swap it into your USDM chassis. Cap them off or take it completely off and do whatever you want with it. I drop kicked mine into another dimension.