02 sensor trouble shooting

[jabb]

Oh no more O2 sensor stuff sorry.....

I had a problem where I had a slight stutter or hesitation in my 84 Carerra. After doing some research I deciced to disconnect the 02 sensor and what do you know it ran without any hesitation. The hesitation I felt was between 2500 to 3000 rpms and when cold.

Anyway I decicde to do some testing with the sensor .... according to the bently manual the output from the sensor should be 100-900 mv. I tested mine and at idle I got 100 - 150 mv which was on the low end of the range. I then disconnected the heater wire and the O2 sensor put out about 480 -510 mv right on target. (All this was done on a warm engine) I then slipped the heater control wire back on and watched the voltage steadily drop off..... disconnected and up it climbed to the normal range.

Took the car for a ride with the o2 sensor connected but heater circuit disconnected and it ran fine...... no hesitation hooked up the heater circuit and the hsitation was back........

Looks like the heater circuit must have some type of short in the sensor when it is hooked up that causes the system to run lean.
with out the heater circuit all is fine...... I will replace the O2 sensor just thought this was interesting and wondered if anyone else had tried this type of test......