Andrew, A properly working one wire (narrow band) O2 sensor will act like you describe. They really only tell you if the mixture is rich or lean. Even with a 10 turn potentiometer on the the mixture control, it takes very little change of that control to transition from rich to lean or lean to rich. From Dennis' description, he may heve been seeing a drift in the signal while constantly rich or lean without touching the mixture control or changing anything else. Is this correct, Dennis? Steve Boese RV6A, 1986 13B NA, RD1A, EC2 From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Andrew Martin <andrew@martinag.com.au> Sent: Sunday, August 18, 2013 7:03 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Oxygen Sensor ground Thanks Dennis I'll try that also, I've been wondering about this as my O2 sensor seemed really sensitive. using a single wire Bosch and reading on the EM2 goes from full rich to full fine with very small movement of the mixture. hope adding the earth helps as fine tuning has been difficult, so far been doing tuning more by ear, but hard to do the fine settings. I was thinking that because I have a very short exhaust pipe from the header(no muffler) that I may have had air reaching the sensor between exhaust pulses. Regards Andrew Martin On Mon, Aug 19, 2013 at 6:23 AM, Dennis Havarlah <clouduster@austin.rr.com> wrote: My single wire O-2 sensor data has been wandering up and down during flight lately. I finally decided to add a ground wire to the sensor case and that fixed it. The sensor uses the exhaust pipe as it's ground. I used a stainless steel screw type hose clamp to hold the wire on the shell of the sensor. Dennis H.
Andrew,
A properly working one wire (narrow band) O2 sensor will act like you describe. They really only tell you if the mixture is rich or lean. Even with a 10 turn potentiometer on the the mixture control, it takes very little change of that control to transition from rich to lean or lean to rich.
From Dennis' description, he may heve been seeing a drift in the signal while constantly rich or lean without touching the mixture control or changing anything else. Is this correct, Dennis?
My single wire O-2 sensor data has been wandering up and down during flight lately. I finally decided to add a ground wire to the sensor case and that fixed it. The sensor uses the exhaust pipe as it's ground. I used a stainless steel screw type hose clamp to hold the wire on the shell of the sensor. Dennis H.