O2 Sensor

[lpaaruule]

Tuning a carburetor can be a frustrating, and sometimes scary process. I know it was while helping a friend get his Rotec TBI tuned in his Zodiac 601. At first it was so bad his engine would quit at full throttle. It was running way too lean, and we didn't know it until we looked at the fuel flow data later. It has since been richened, but we don't know how rich is really is. Yes it runs great now, and we know it's using more fuel than it was, and we think the mixture is set right.

That was over a year ago, and at the time I thought that it would be great if we had access to an oxygen sensor. Well today as I was surfing the web, I happened to see on Rotec's forum that they are now selling an oxygen sensor kit for $350. You can see a video of them using an O2 sensor for tuning: https://youtu.be/xg6ygAxUyj4?t=8m3s

It sounds like a great idea to me, but there are 2 issues that concern me. First, an O2 sensor is poisoned by leaded fuel, so even if it works long enough to get the engine tuned, you won't be able to use it while flying with 100LL. Second, $350 is a lot of money for a one time use.

Someone told me that Rotec runs with unleaded 94 octane fuel during the tuning process to prevent sensor damage, but I haven't heard that directly from them.

So I decided to look for other options and found this for $130: http://www.wide-band.com/product-p/apsx_d1g1.htm
I just bought one, and plan to use it to tune my engine. I'll have a O2 sensor bung welded on a tube that I can attach to the end of my exhaust pipe. I hope to try it out on my friends Jabiru 3300. I'm thinking that it might be a good way to tune the engine once or twice a year, and just throw out the O2 sensor when it stops working. If there's ever a 100LL replacement, I may install it permanently.

[Brett]

The wide band sensor is still working fine on mine after 70 hours on avgas... I rarely look at it now but was great in the beginning. I just lean by egt temps.