Is Oxy. Sensor Elec.or Exhaust?

[Guest jjohart]

Hi,

first off, I couldn't decide whether my oxy.sensor should be posted under electrical or exhaust, sorry!

Most of my posts in the last year concerned how much my car was stumbling until totally warmed. Despite all the good advice/suggestions I got here-thank you again-it wasn't solved by me and my KG level mechanical/electrical abilities, but after spending around $700 in total labor charges for local garage to find cause.

At this point, my car runs fine, b/c they sent the oxygen sensor lead to the ECU onto a ground post/wire, leaving the sensor unplugged. This has UNDOUBTEDLY solved my car's driveability issues 100%, so I don't want to mess with success!

I did pay another mechanic $75 (a former Nissan tech) to give it a look-over..basically wasting that dough for his mouth, but he did say that there was more than one oxygen sensor out there for Z's like mine, and there'd be driveability issues if they put the wrong one in. So, I'm not finding specific model numbers on the sensor when I pop the hood, and I don't want to bother the mechanic who unplugged it-yet-but since he also HAD replaced the o2 sensor (apparently using his service database called Tech Net for the part number), can anyone tell ME which is the right model number for an 83 280ZX Turbo 5 speed (Pennsylvania state of original sale)?

I did find Afshin's write up of various o2 sensor applications, but alas, his list starts with 84 on..

The last question is, if there's nothing wrong with the sensor, and I'm best off leaving it off, are there any negatives for not keeping it plugged in...like a higher likeliehood of emissions, failure of Massachusetts emissions testing, etc?

Again, apologies for my lack of knowledge/research, but the last question I have, just b/c I'm too lazy to do a search on it, is what is the purpose of an o2 sensor, do modern cars in the US HAVE to have them, do diesels/Euro spec. cars do away with them, and why does it wreak havoc on the car's performance, via the ECU, when one of em' goes bad?

Thanks

John