I'd imagine the one that is bad is the one on the passenger side. It suffered the burnt harness.

 

Since voltage is supplied TO the O2, shorting it will have little detrimental effect on it's quality. What has a much greater impact is contamination. Either from oil or coolant and the most common is running too rich. So your O2's could be defective but not likely from the harness problem you spoke of.

If you have evidence that shows one side good then the prudent move would be to switch them to see if the problem moves or not. Saves you from buying un-necessary parts.

 

Ok, replaced the passenger side O2 sensor, plugged the driver's side back in, drove it and it runs like crap again. Went back out, unplugged the PS O2 sensor and it runs fine again. I'm going to have it scanned tomorrow. What should I be looking for guys? I would really like to finally get this car figured out. Your help is GREATLY appreciated.

 

Good luck man, chasing electrical problems are the worst.

Best bet would be to get a scanner on there and monitor for any abnormal sensor readings.

 

That's what I'm doing. I'm going to have it on a scanner tomorrow, but I don't know what would constitute an abnormal sensor reading. Anybody have "normal parameters" for things like O2 sensors, MAF sensors, etc?

 

My online scanner guide might help:

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

Thank you, Fred. I'll be printing some of those pages tomorrow.

 

The easiest way to find out what is happening is to disconnect the one that does not sweep between a low number and a high number. This should have the result of making it go to about 450mV. If it does not, you know there is a problem usually with the wiring.

With the O2 still disconnected. If the numbers are consistently above 450, then the next thing to do is put a jumper from the black wire to purple/white and also the tan/white wires. The reading should now be below 200mV. If it does not change with the jumper, you know you have a break in the wiring. If the problem is that it stays below 450 before you put the jumpers in, then you know the wiring is shorted to ground.

In very rare occasions that I have not witnessed, the PCM could be defective. But the wiring should be rung out first.

 

I hooked it to the scanner with the O2 sensors plugged in and it reads anywhere from 450 and above (into the ~800's) for both O2 sensors. I noticed that the car runs fine in open loop but as soon as it switches to closed loop, it starts to stall out. I'm lost and I'm getting very frustrated with the car. I don't know what to do.

Edit: I'm borrowing a GENiSYS scanner from a friend of mine. I'm reading up on how to use it right now. I'll have it through the weekend and will post updates as I come across things.

 

My readings for the O2s are between .150 to .920. They switch back and forth really fast.

Keep us posted with your readings. Thanks.

 

You have found the major symptom. Your O2s are reporting that the engine is running rich all the time. If you were to look at the fuel trims, you would see they are going lean and this is why your engine runs good in open loop but poorly in closed loop. So far it appears you have the same problem I did with the O2 wiring.

I gave you the way to investigate the problem. Disconnect one of the O2's and jump the black to purple/white and also the tan/white wires. Now with the engine running, confirm the readings go below 200mV. If it does, move on to the other one. If either do not change. That's the one with the broken wires.

 

Speedygonzales, you've been a great help in this thread. I will do the diagnostic to the O2 sensors this afternoon and hopefully be able to pin down the problem. I'll report back tonight and let you all know. Thank you again, everybody. And thanks to you, Speedygonzales, it seems that you're keeping an eye on this one and I appreciate it.

 

With the car running and either one or the other O2 sensors unplugged, it reads 443 mV. I didn't try the jumper because you said to try that if the numbers are consistently above 450. These are just staying there, not above or radically below. Should I try the jumper wire? I don't want to cause any problems.

 

Yes do the jumpers.

 

I'm on it. I'll be back in ~10 minutes with my findings.