hi all,
 
when i got a new oxygen sensor the plug was different to what I had. so i popped the pins and put them in the old plug, very very carefully.
 
however, my mechanic thinks i may have buggered something up as the signal is all wonky. it seemed to drive ok when i first replaced it, but now 3 years later i've been having ongoing issues with a slightly stuttery engine (when it's warmed up and under low throttle) with occasional surging. done all the usual suspects already (complete replacement of plugs, leads, dizzy cap, rotor. plus cleaned injectors blah blah blah). so it's probably the sensor, especially because of the wonky signal.
 
so, it's a 4 wire sensor off a '94 3s-gte. anyone have wiring diagram for it?
 
and if it's not the wiring, but the sensor itself is stuffed, anyone know a part number and/or best place to get a new one?
 
cheers.

try unlugging the sensor and see how the car drives.
My Gen3 is experiencing the exact same surging, hesitation problems. With the sensor unplugged the car drives perfect just a little rich. I've done all the ig components as well so I'm going to try a new sensor and see how I go.
I've ordered a new genuine gen3 oxygen sensor from Amayama in Japan for $160 plus shipping.
Part number is 89465-29805
http://www.amayama.com/

Oxygen sensor wiring  

Thanks guys. Sent the diagram to the mechanic.
 
I also unplugged the sensor for the drive to work this morning. Does indeed seem to run ok with it unplugged (although the cold start this morning seemed a little rougher than normal, it settled down quicker than normal as well. It's always had cold start problems though).

Have you made any progress with this issue?
I'm still waiting for my new sensor to arrive from Japan. 

Car still hasn't gone back to mechanic yet. Did a few longer drives today with sensor unplugged. Was still a little missy occasionally. Mine is mostly when the boost gauge is showing major negative pressure, so I'm also thinking vacuum hose issue. But then also the coolant temperature sensor is iffy (crack in the plastic). I'm happy to throw money at this to fix it, I just don't know where!

The coolant sensor is surprisingly finnicky...

I'm running a 93+ ECU in my 92 and i've had problems with my 4-wire sensor. Have you checked the codes at all?
Mine has the O2 sensor code (which i think is 21, i havent checked in a while). That may give you another hint as to the problem too.
the ECU coolant sensor is code 50-something.
Also, just because the ECU light isn't permanently lit on the dash doesn't mean there aren't any codes stored.

Well I drove for a bit with the o2 sensor unplugged. Was still having misses and surges. Plugged it back in, took it back to the mechanic, and now apparently it's signal is fine! But I have an exhaust leak. So now I need to find an exhaust place. And also get new springs and struts because they're loose and wobbly at the front.

Oxy sensors are rarely responsible for any low speed/low rev "issues". ECU corrections based on this sensor only apply at medium to high load
 
there are 2 temp sensors. the one going to the ECU (2 wire) is resposnible for many issues, particularly running rich. basically, as soon as it goes off, the engine starts running rich as the ECU interprests it as a cold engine. this wont throw a code until the sensor fails totally. The BGB tells you how to test the sensor, but its hardly worth the effort as they are cheap
 
we have new Oxy sensors in stock, depending on model, $95-$135

Do you have temp sensors? And how much are they? I've always been a bit dubious about my current one's reliability.