i did my t2 swap a little while back, and the 02 sensor has never been hooked up! i couldnt find the wire for it at the time.... then i replaced the alternator and voala!! there was a loose wire (but no connector) (just a wire)........ i assume its the o2 sensor wire, but want to make sure before i connect them! its a black wire w/ a yellow stripe..... is that it??????

by the way.... what happens when a 02 sensor is disconnected??? my car runs super rich..... is this why???

 

oh.......its a 88 t2 motor and wiring harness..... not a 91... the chassis is 91, but the motor is 88

 

bump.....

 

Should be black, no yellow stripe. Don't know about the turbos, but the NA's have the sensor wire running out from the back of the engine, below the UIM...Coming out of the same harness that feeds the primary injectors and rotor housing ground...

If in doubt, look at the color of the wire going into the ECU pin for the O2 sensor...

 

which one is that???? i can look if someone can lead me in the right direction..... crappy w/ wiring....

 

Amazingly enough, my '88 schematics show it as grey near the ECU (I always thought it looked black, lol). If you're at the ECU, it'll be the middle plug, 2nd one over from the right, on the bottom.

If you want to make sure the wire you're seeing near the alt is the O2 sensor wire, just clip the strands to ground with some alligator clips (might want to disconnect the battery first, just in case it's a power wire for something), then read the O2 sensor pin at the ECU to ground with a meter (resistance). If you get continuity, you've found it (or, the REAL O2 sensor wire is grounded somewhere, lol, in which case you'll still have a ground if you remove the clip from the black/yellow wire near the alt)