blue94

iTrader: (7)

My car has been runnning very poorly at part throttle. Wide open and idle are fine, but crusing around town or on the highway it wants to start missing and seems to be running very rich. The O2 sensors seemed to be stuck at about 450mv, so I unplugged them to see how it ran when it was in open loop. Much to my surprise i was still seeing readings of 450mv even with the O2 sensors disconnected. Do I have a wiring issues that is causing the pcm to see 450 mv even when the sensors are unplugged? The sensors are less than 6 month old Delcos. Car is a 94 TA with a 6 speed.

gatorhead

iTrader: (4)

did you wire extensions in when replacing these or did you use factory wiring? Sounds like there could be a short in the wires.

blue94

iTrader: (7)

factory wiring, but I did have a short years ago in the bundle of wires that goes to the drivers side o2 sensor, speed sensor on the transmission, etc.

I suspect that there is a short in those wires again. Would this cause the pcm to see voltage even when these sensors are disconnected?

gatorhead

iTrader: (4)

Take a digital multimeter and set it to ohms see if it is or not. It would be quick and easy to see if it were.