i have a 95 b18c1 swap in my civic with an old school skunk2 intake manifold which eliminates the secondary butterflies... can i run the stock p72 and just wire the knock sensor and then it should be good? i was told that without the secondary butterflies it disengages the vtec..... any answers for me?

 

You can run the stock P72 -- the IAB (intake air bypass) does not trigger a CEL nor does it disable VTEC if it's not working/connected. I ran this setup for quite some time.

 

Secondary butterflies not being hooked up will not throw a CEL, and it will not disengage VTEC or keep it from working.

BUT!

Your car will run like **** with a P72 ECU and Skunk2 manifold. The manifold likes a 5500rpm-6100rpm VTEC cross over, while the P72 VTEC hits at a too-low 4500rpm.

Buy a P28 ECU (from any SOHC VTEC EX/Si 92-95 Civic) and have it rechipped, or possibly even have your P72 rechipped with an Uberdata or Crome program and have it tuned on a dyno. If that's not an option buy a prechipped pogram meant for a GS-R engine with the Skunk2 manifold.