What is the function of the thermo couple that comes off of the exhaust pipe behind the catalatic converter?

 

The tube that runs up to the Carb? It is air from the air pump to help the Cat burn crap off.

 

I'd assume it's for the exhaust overheat detection. Although I thought that sensor was bolted to the floorboards.

I'll have to research it a bit. Someone else might be able to chime in on it.

 

I dunno, but I broke mine off....opps. Didn't affect anything so far. If there is anything wrong with what I did please let me know

 

There isn't a thermocouple of any kind in the stock exhaust system (unless someone added one to measure EGT). If you are talking about in front of the cats, there is an O2 sensor, if you have a GSL-SE. This may be mistaken for a thermocouple. As Pele said, there also is a sensor that detects exhaust overheat, but it is placed on the passenger side floor board, directly about the main cat.

If you have a pic of it, it would be easier for us to tell what exactly it is.

 

First of all, my RX-7 an 85 base model. I'm asking a little black box with a wire coming out of it, on the left hand side of the pipe between the cat and the one that snakes up to the muffler. The wire disappears upwards, also to the left of the pipe. I was going to have the neighbor make a replacement pipe, then we ran into "the wire". While he did weld a patch on "the big hole" to tide me over til storeage time, there's still something leaking under there. We did find out that it is to detect overheating. The pipe itself must be one expensive item since everything else to do with the exhaust is in better shape that pipe is. The mounts for that stupid snake-like tray thing(sorry for the terminology - I'm a girl) that originally protected the pipe ripped a hole in the pipe. I hope the car doesn't need one of those tray things because neighbor guy promptly chucked in in a barrel outside his garage, while muttering something like, "that would make a hell of a noise when it falls off!"

Anyway, does the car need the sensor? Rotary mechanic friend - works for a Mazda dealer garage says - yes and will get us one for the dealership price. Of course, he's worked on RX's since they were invented, and wants us to put this baby back to original. Neighbor guy, with the exhaust business, will cut me a screaming deal. Whaddaya think?

A picture? The car sits, what, 8 inches off the ground? Maybe? I might break a nail!