I'm having trouble with the car running horrible when going to closed loop. I thought I would check the grounds first but where are they at? this is a 94 Z28

 

In the 4-wire sensors, the sensor element is grounded through the PCM via the tan (right bank) or tan/white (left bank) wire. The heating element is grounded to the chassis via the black wire.

 

ok there is a brown and purple and black and light tan. The two brown wires "both sensors" go in to one and then there are two more brown wires coming out of the bundle of browns but they are cut off. So I can't see that the brown wires are doing anything because they are just hooked togethor.

 

http://shbox.com/1/HO2S_connector.jpg

 

The full diagram of the O2 sensor wiring is also on Shoebox's site:

http://shbox.com/1/1995_pcm2.jpg

 

got it figured out. The two brown wires that were cut needed the 12v supply. The kid that had the car before had an open loop tune so that's why he didn't have the heaters hooked up for the O2s