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O2 Sensor without Cat


Vehicle Information: Model: 911 Carrera; Year: 1984; Body Type: Targa; Engine (type, size, modifications): 3.2 ; Total Mileage: 187,000;

My mechanic tells me that I don't need to have my O2 sensor connected since I'm not running with a catalytic converter--I have a test pipe and Dansk muffler. The car backfires and cuts-out on it's way to redline and back down. I occasionally run a Fabspeed Pre-Muffler which accentuates the backfiring/cutting-out and makes the car sound terribly embarassing! On the other hand, with my O2 sensor plugged in, the car surges very subtly and you can feel the power cutting in and out as you accellerate and cruise on steady throttle, and still b/fs and cuts-out. New wires, plugs, coil, DME relay, rebuilt DME, Weltmeister chip (acts the same with the stock chip) and MSDS cone breather. My DME fuel quality setting is set at +1 click CW from full CCW (problem is the same at full CCW)as an experiment. The O2 sensor is the three-wire type and looks black-ish in appearance. Does it sound like it should be replaced? Or, is it really just "extra weight" if you're not using a catalytic converter.

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