o2 sensor
 

seems like the piece of the harness were the o2 sensor clips on too was ripped off, put back together and covered by some black tape for a temporary fix. basically the wiring was ripped to the very bone of the clip and i doubt i can repair it. im do for a new harness anyway. how much do engine harnesses usually go for?

Its completely repairable by someone that can crimp or solder on new connector(s).

would a disconnected o2 sensor cause the down pipe to heat up to the point were its glowing at idle?

It can cause the car to run a little richer. FYI, a new wiring harness around $700. Its a single wire so there is no problem splicing a new O2 sensor in place.

i payed $800 for mine about a year in a half ago and my mech said it went up since then..

I just bought one from Ray Crowe at Malloy Mazda, it was $800 total tax/shipping.

But you should be ablt to repair that wire....

my O2 sensor came unplugged and i saw no difference in performance. i'm running a PFC so does it even make a difference with a stand-alone??

i think PFC actually runs better without the stock O2 sensor if you are running on the stock PFC map.

def not running stock maps

well since it wasn't the wire on the o2 sensor that was ripped, it was on the harness end of the connection that did, im gonna go search'n around for someone who can professionally put enough wire back in the clip so that i can solder it back on to the harness. about the overheating down pipe then, i just took off my uim and found one vacuum hose that was ripped and another that was tore off completely, and im still waiting on ordering a hard pipe kit from fd newbie for my factory airbox since the lower intake hose tore. maybe a mix of all this had to do with it heating up.

I'd have to disagree, on my PFC with a base map my car ran like shit at low revs especially. Backfiring lots and was way over emissions. Put a new one in and it ran better and emissions dropped a lot.

But I guess it depends on the car too :)