What could cause the error codes to flash an O2 sensor error...
 

17 - Feedback System (poss O2 sensor) - Feedback cancelled

I figured out why my car is running like shit. The trailing plug wire on the front rotor isn't getting a good bite on the plug and I don't think it's firing most of the time, if ever at all.

Could the extra crap thrown out the exhaust that wasn't burned cause the O2 sensor to flash a code at me?

The check engine light only comes on when I'm cruising in gear, usually in fourth or fifth, but sometimes in the lower gears as well. As soon as I let off the gas the light disappears. When I get back on the gas, it comes back on, but not right away. It usually takes a few seconds.

I'm not sure what effect the O2 sensor has on the car, or when it comes into play as far as the ECU is concerned. Could someone educate me?

The O2 sensor is used for closed loop operation - meaning on the freeway, or in another non loaded situation like crusing on a flat road, the ECU uses the O2 sensor to determine if you are just cruising. If you are, then it drops the injector duty cycle a bit to give better gas mileage. If the car runs excessivly rich for a prolonged period, the O2 sensor can go bad due to all of the extra fuel burnt on it. I would change the O2 sensor. Until then, you aren't hurting anything other than your gas mileage :D

Alright, so I guess my theory is correct. :D Thanks Dave!

I did notice that my gas mileage wasn't what it should be lately. So I guess the first thing I need to do is get some new spark plug wires, and then an O2 sensor.

Had the same problem
 

I had the same problem on my '91 TII after in installed my new engine. The O2 Sensor wire was baked nicely. So when the engine was out I soldered about two feet of new wire onto the baked wire. Installed the engine and started getting the code 17 at the same times you got it.

The fix was simple. I had a broken o2 sensor wire somewhere in the harness. It was confusing because I did a continuity test on the wire where it goes into the ecu. Perfect continutiy. Not only on the pin it was supposed to have continuity. But on like 6 other pins to. So my wire was shorting out.

So I ran a new wire from my 02 sensor through a new hole in the fire wall and straight to the ECU. FIXED! I was sooooo happy. Not sure if this is you deal but it was mine. If you need a wiring diagram I can take pics with my digital camera and give it to you.

James

my wire was shorted out to but I can't remember what code I was getting. but when the light came on it stayed on. check the voltage of the O2 with it pluged into the harness, then unplug and check again, if the 2 #'s are way off, then it's a wiring problem. if same, or no reading at either, get a new 02, with a shorted wire you will get no reading with it pluged in (maybe .01volts. should be over 0.1) but will read ok when unpluged, unless the O2 is already fried.