do i need 2 o2 sensors? i have one stock and am using a 92-93 gsr integra manifold with only one o2 sensor hole. the reason i am wondering is because my crx has 2 o2 sensors, one for vtec and the other for normal functions. thank you for all imput.

 

Yes, you should have the two o2 sensors, but if you splice the wire for the secondary 02 into the primary 02 wire, it'll run fine. I ran mine like that for a long time, until I got a header, then had my buddy weld in a bung, and I wired them both up. It didn't run any different, so it prolly wasn't worth it.

EDIT; the second o2 sensor isn't for VTEC. Once the computer gets to a high enough RPM, or load, it'll switch over to closed loop mode, and bypass the o2 sensors, and run strictly the default map. That's why if you have an air/fuel guage and you get into VTEC at light throttle, you'll see it go from stoich to rich in a split second.