[bconnaway]

Originally Posted by JackandJanet

First time soldering? Certainly could be the cause of lots of problems. They could arise from having a poor solder connection to heat damage on the sensor itself during the soldering process. (Although since O2 sensors are exposed to great heat in operation, I suspect that is not the problem.)

The "stuck rich" signal from one of the sensors indicates a sensor malfunction. Those sensors are actually fairly complicated devices, and they incorporate a heating element to get them working sooner. Here's a description or the Heated O2 Sensor:

The HO2S detects the presence of oxygen in the exhaust and produces a variable voltage according to the amount of oxygen detected. A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a voltage signal less than 0.4 volt. A low concentration of oxygen (rich air/fuel ratio) produces a voltage signal greater than 0.6 volt. The HO2S provides feedback to the PCM indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation. The HO2S generates a voltage between 0.0 and 1.1 volts.

I really don't have any brilliant ideas about this, but I'd have to suspect a problem with the sensors themselves at this point. Trouble is, they're expensive, so you don't want to replace them if it's not the problem.

Can you tell me exactly what it was that you soldered? Was it "extensions" to the wiring? If so, did you insure you had a solid mechanical connection between the two wires before applying solder and, what did you use to insulate the exposed connection? Solder itself is not really there to conduct electricity - it mostly makes the connection "permanent" and coats the connection to prevent oxidization (corrosion).

- Jack

When I soldered them, this is the process I used:

1. Cut the wiring on the O2 sensor about half way up
2. Strip wire and the wire for a 6" extension
3. Heat the wire from the O2 sensor with the soldering gun
4. Once the wire is hot enough, place a small amount of solder on that wire
5. Heat the wire from the extension and once hot enough, put solder on this wire
6. Put the wires together and heat the solder from each wire until they connect
7. Repeat process for remaining 3 wires
8. Electrical tape the soldered connections
9. Electrical tape the entire extension

I was doing this based on what my roommate had told me to do (he's an electrical engineer), but this process definitely has the solder as the main form of contact between the wires. I could go back and try to re-solder the wires to see if that helps. If not, I may end up having to just buy new O2 sensors and actually buy some commercial extensions. Biggest thing though is I really don't want there to be a different problem, replace these sensors, then have them ruined. Just trying to go through the list of the minor/cheaper fixes before tackling that.