1989 240SX: Oxygen Sensor

[Golden]

I am trying to replace the o2 sensor in my gf's 89 240sx. I used a 22mm and it came out easily but there is a big-*** adapter thing that uncrewed along with it! It has hex-sides larger that 27mm. (my largest socket) Chiltons doesn't mention it and I can't find anything about it. Eyeballing it, it appears that the o2 sensor screws into it and then it screws into the exaust manifold. (both right-hand threaded) Anybody know what the heck??? I am sure I can resolve this but I just wanted to know if anybody ever had the same problem.

[NISTECH]

it is a bung to hold the o2 in. pretty common on nissans. Clamp it in a vise by the hex section [btw its 1 1/8 inch/30mm] then unscrew you o2 from it. be sure not to damage the threads on it or it wont go back in the manifold.

[Golden]

Solved it. 1 1/4" and 22mm wrenches. Lots of PB Blaster. And they came apart. The slight hesitation upon acceleration went away with the new O2 sensor. BTW: Replaced a damaged hose under the BPT (above the EGR) and my other drivability problem went away. Car used to idle badly for a minute after starting up cold. Thanks for your help.