Last night, on the way home from the track I got cought in a nasty thunderstorm. After riding in it for about 15 minutes, the car started developing a missfire, so I pulled under an overpass to take a look at it. I couldn't find any obvious reason for the missfire. When I started the car back up, it seemed to run fine again so I just drove on.

After a few minutes, the car started missing again and the check engine light came on. I pulled over again and brought out my laptop w/ tts datamaster and it showed trouble code 65, right o2 sensor rich. The mV reading on the right o2 was stuck @ 1077 mV while the left one was bouncing around like normal.

I disconnected the battery for a few minutes to clear the PCM, started it back up and the dtc was cleared, but the missfire was still there. As I was driving, it seemed like the missfire would randomly go away for a second or two.

It was sunny out this morning, so I started it up and it seemed fine, so I started going down the driveway and it started missfiring again, this time I heard a slight pop out of the exhaust a few times. I hooked the laptop up to it again and this time it showed trouble code 64, right o2 sensor lean. The right LTerm BLM was stuck at 160 and the right o2 mV was @ 0mV.

When I put the pacesetter LT's on the car, they didnt have a nice molded o2 extension, so I had to splice 4 wires in. I know it seems obvious that the right o2 sensor or the wiring is causing the problems, but I didn't know a bad o2 sensor would cause a huge missfire like this.

Can anyone offer any insight as to what would cause this kind of problem. Could 1 o2 sensor really cause this kind of a headache?

 

I'm no pro but I would think with that o2 sensor reading incorrectly, the ECUs inputs are inaccurate, thus so are outputs (for fuel). If it reads lean it will richen the mixture, never see it and continue to do so until you get a backfire of ecxess fuel in the exhaust.

 

Sounds like the water was shorting the wires, first the signal wire to the +12V heater wire, then later the signal wire to the sensor or heater ground wire. If the sensor is reading 1000mV, the PCM is going to see it as "rich" and start pulling fuel out. At some point it will be running so lean it will misfire. If the sensor is reading 160mV, the PCM sees it as "lean" and starts pouring in fuel. At some point it will be running so rich it will misfire.

 

Thanks for the responses. I pulled the plugs a few minutes ago and they were black as hell. I checked the spliced o2 extension wires and I had taped the 4 butt connectors together. I figured the insulation that's built in the connector was enough, but when water gets in there I can see why it would get shorted. I bought a new o2 sensor and I'm gonna order a molded o2 extension to replace the current one. I can't afford to do this to the left side yet, so I'm just gonna do a better job isolating the splices until I can afford a new o2 sensor and molded extension.

 

Incidentally, never splice the wires from the O2 between the connector and the O2. The passages that the wire pass through the body of the O2 are the same locations that the O2 gets its ambient air from. When you splice the wiring, it interferes with this ambient air flow into the sensor. Many repair manuals suggest not even using dielectric grease on the connector for this very reason.

 

Thats an interesting fact. I wonder why pacesetter includes a ball of wire and 8 butt connectors for their o2 extension kits?

Thanks for the info! I'll go ahead and take care of the other side too then.