O2 sensor doesn't fit???

[slipnfall]

Hi there, I think I might be loosing it here.... Do O2 sensors differ from year to year on the S13's? I have a '91(says so in the door jam) coupe with an empty engine bay. I kept the original O2 sensor from *this* car.

Now, I bought what I *thought* was a 1991 KA24DE from another member here. I used this exhaust manifold, collector, downpipe, b/c it was less rusted.

However my original O2 sensor does not fit into the O2 bung! The O2 sensor is smaller: doesn't even touch the threads. I'm *pretty* sure I'm putting it in the right place: it's the bottom-most hole on the collectors, right? The one on the side is for the EGR & the lower-most one on the DP is for the AIV/PAIR, correct?

I just want to be sure that A) I'm putting it where it's supposed to be, and B) O2 sensors don't differ from early-to-late S13(and I in fact don't have a 1991 DE engine here). I'm sure it's from a 240sx, b/c the kid that sold it to me pulled it for a swap.

Someone please set me straight on this!

Thanks for reading,-Jamie

[InsanityInc]

The original O2 sensor should have a nut that's threaded on both the inside and outside surrounding the threads. You have to take that nut off the original one and then thread it onto the new one.

[slipnfall]

Phew, I was hoping it was a simple oversite like this: my original[blown] KA is ~150miles away under a tarp so I couldn't just go re-examine it.

Is this b/c Nissan uses this exhaust mani on another vehicle(w/a different o2 sensor size)? Either way, I'm glad to hear I'm OK. After the post I went to an online parts store and realized all KA24DE's in the 240 have the same O2 sensor P/N.

Thanks much,-Slip