first of all not sure exactly what this is called. the piece that the vac lines plug into the tb, the iac plate to be specific. usually they have three lines. now i've seen ones with just two lines coming out and where the third opening would be, it's not. came stock like that. now i don't remember if i saw these on tgps or where?
:icon_question: OK
one of those lines goes to the charcoal canister which i am removing. believe this would be the best way of blocking that line off.
the ones with three lines are for newer ('91- '94) 3.1 MPFI engines that have digital EGR, so there are only three nipples - one for MAP/FPR (shared), and one for cruise control/HVAC (also shared) and the other for canister purge solenoid. the TGP and older 2.8/3.1 engines have four nipples, one for MAP/FPR, one for cruise control/HVAC, one for canister purge solenoid, and the other for vacuum EGR.
i'm in the process of simplifying the lines so that i don't have those hard plasic vacuum lines that run under the plenum (prone to cracking from heat and impossible to access or R&R without plenum removal). i ditched EGR completely and then drilled & tapped the EGR hole in the plenum so i could add a 4-port vacuum/boost distribution block from TurbosUnleashed.com. it currently only sources my boost gauge but next time i have the plenum off it will be sourching my MAP sensor and HVAC/cruise control:
http://www.turbosedan.com/cutlass/engine/DSC03003.jpg
http://www.turbosedan.com/cutlass/engine/DSC03004.jpg
http://www.turbosedan.com/cutlass/engine/DSC03008.jpg
after that the only thing the top IAC plate will be used for is FPR and canister purge solenoid, leaving me with NO lines running under the plenum :) i might just delete canister purge solenoid completely and source the FPR from the vauum block as well, then i could remove that top plate and then fill it with epoxy and cover it with a steel anodized plate. FWIW my boost gauge is sourced from the nipple behind the plenum (previously used for the automatic transmission vacuum modulator) and my boost conroller is an M&M Racing grainger valve style MBC that is sourced from the nipple on the compressor outlet. i guess i just like clean, simple and easy to work on.