I recently changed the exhaust in my RX7(1987 Turbo) and I noticed that my O2 sensor was unplugged. No big deal since I was replacing it anyway, but when I tried to find where to plug it in I could not find the other end. Can some one tell me where the connection should start for the O2 sensor plug. If possible a couple of pics would be a great help. The car has be hesitating has this been the problem?

 

should be right behind the manifolds on top of motor...near firewall

 

I can't find anything there but I didn't have time to take the intercooler off, but from what I can see I don't think I'll find it. Where exactly does it start?

 

It's been a while, but the sensor wire runs into the wiring harness to the right of the bac valve, and a couple inhes down. If you don't see an exposed end look into that harness. The wire will break off right where it enters that harness. In the harness, the O2 sensor wire is small and it is covered with a wire cover, which is covered with shielded cable and then covered again. If you need to splice into the wire in the harness, make certain that the shielded cable does not come in contact with the O2 wire, or it will take it to ground, and no signal. Best to pull covers back, solder a new wire onto the broken one, place a heat shrink over the connection, then pull the shielded cable back and tape up. Before, and during the "fix", it's a good idea to check to be certain that you have continuity at the ecu terminal to the end of the O2 wire. Do this with a meter, and place one end on the wire at the ecu and the other end on the new wire you soldered in place to be sure it's reading ok, and no ground. You'll probably need a wire extension to connect the meter as the leads arn't that long.
Hope not too confusing!

 

Yeah, its right there in between the bac and the water pump housing neck.

 

do a search for a thread i just had on this same topic
i had pictures posted in it showing where my wire was broken off

 

Thanks, I think I found it, plugged it in (connection is screwed up) but it seems to work much better. I still have a little hesitation just before secondaries kick in, is there anything I can do to try to smooth this out?