where does this ground go, I dropped the fuel tank and forgot where to connect this. Have to build a new one. 1987 rx7 turbo ii

 

Given the perspective of your photo, it's hard to say. If that's a braided ground strap, than it connects from muffler/y-pipe flange to frame. It's there for radio interference suppression, but I doubt it does any good.

 

i noticed the one on the rear left muffler the other day when i ripped out the exhaust. i kinda figured it was a reference ground for the single wire o2 sensor. either way its gone now!

 

Mazda lists it as Audio System Noise Suppression and Ground Cord (p/n FB03-66-970). I used to replace mine, when broken, when they were available from Mazda, but they are NLA. Any braided ground strap will work if you can find one with the right size lugs. I'm not sure that's its really necessary.

 

That's crazy that a rando ground on the *** end of the exhaust does that!

I tossed it when I ripped off the oem exhaust the other day. I'm not going to run any radio, much less the oem.

 

That ground is long gone on my car. Didn't even know that it existed.

Although I've always had terrible radio reception even after replacing antennas, so maybe I'll make a new one just for fun and see if there's a difference.

 

did you check the one in the windshield? When I took the wiper cowl off during disassembly I noticed the antenna lead going to the windshield was corroded pretty badly.

 

I don't use the windshield antenna, I found it actually hurt reception.

My current setup is the one that's worked best for me so far: generic fixed antenna from the auto store, nothing else.

 

The rear mast antenna is the best choice for an aftermarket AM/FM receivers. Mazda (and a few other manufacturers) back in the 90's used the so-called diversity antenna system. The receiver used an internal signal strength comparator that acted as switching circuit and would select the strongest FM input signal between the two antennas. The purpose of diversity antenna system was minimize multi-path and fading by choosing the most robust link.

 

I didn't know that it actively switched, I always thought it combined them somehow.

Either way I actually found this to be the case even with the stock stereo - the windshield antenna being plugged in either hurt reception or didn't help. It's hard to say after so many years though whether that is the fault of the antenna system or the stereo. Mazda wouldn't have gone to the expense of installing it if it didn't at least help some of the time.