Oxygen Sensor Wiring
 

I searched around but never really came to the answer I was looking for.

The 1986 944 had a 3-wire heated sensor. Upon looking at mine, I discovered that the wires are black, white and white. I assume the black is the signal wire, and the thewhite wires are the heating circuit. Correct?

I installed the new (universal) 3-wire sensor using the supplied instructions. The grey wire was the signal, and the red and black for the heating circuit. After installation, the car no longer has any slow acceleration points, and seems to be a LOT more peppy, more zip than it did previously. But, I've noticed that my MPG meter reads less than it did before hand. For instance, on a straightaway I drive daily to work, it read ~35mpg. Now, it's below 30, yet the car seems to be running better.

Do you think I have the O2 sensor installed properly? The original sensor had 130,000 miles on it.

Correct, the black wire is the signal wire. As long as youre sure you installed it as instructed, then it's in right. I can only guess that maybe your old sensor bad and causing the car to run a little lean, giving you better mileage. This is the opposite of what just happened to me, where my sensor was bad and caused my car to run really rich.

Thanks for the quick reply.

Just wondering...How could I tell if the car is running rich or lean at this short of a time after install? I could fill up multiple tanks and see how the MPGs really are. Is there something in the meantime I can do though to avoid running rich/lean in the meantime? Will there be soot buildup in the exhaust, or on the spark plugs? Do I just have to wait to see how things go in the next month or two to see where I stand?

Exhaust will have a distinct smell and make your eyes tear. Black smoke from the exhaust under hard acceleration or when you lift off the throttle (from high rpm). The rear of the car will also get a bit dirtier, mostly black soot.

These are all very general ways to determine mixture and dont tell you much. The right way to do it is get the car on a dyno with a sniffer up the exhaust pipe.

Also dont quote me on this, but i think when sensors get old and go bad, they more often make the car run rich than lean.