Disconnecting the O2 sensor
 

Will my 1981 911SC run leaner or richer with the O2 sensor disconnected? The reason I ask is that I have been running with 87 Octane gas and I never noticed any pinging. Recently, I disconnected the O2 sensor, I heard a very slight ping when it is under load. Does it make sense? Will the engine gain more low end performance. I notice a little bit of low end performance increase. Is that my imagination?

It depends on where the base mixture is set.

With the sensor disconnected, the Lamda system will assume a cold engine and default the frequency valve to 60% duty cycle (for 1981-83). With everything connected and working, the Lamda system will tweak the frequency valve duty cycle up and down based on the signal from the O2 sensor.

Tom

Thanks Tom. If the base mixture is set at factory setting, is 60% duty cycle richer or leaner? Also, how do I determine the level the base mixture is set at?

Can any one explain to me how to adjust base mixture? I recall reading performance improvement by disconnecting the O2 sensor and setting the mixture a little richer (1981 911SC). Please share your experience. Thanks