Quote Originally Posted by Delta Whisky View Post
Many thanks for the video - I'm interested in any details you can share (remember?) regarding the O2 sensor and the threaded bung or receptacle you used. As far as displaying the AF ratio - is there any chance a volt meter with a nearby conversion table could work? I'm also assuming that by using one O2 sensor in the middle of the muffler you made corresponding carb set ups and didn't worry about any minor differences between the left and right sides.

Your timing couldn't be better for me. Maybe you saw in a different thread my exhaust stinger departed the aircraft during its last flight. There is some evidence it might have been related to insufficient clearance between the cowl and the exhaust stinger but there is also considerable evidence it was the result of a vibration issue. Without the capability of a thorough vibration test I'm committed to address both possibilities - and it won't hurt to make the engine as smooth as possible for comfort reasons. Anyhow, when the new muffler shows up, I'll be ready to add the O2 sensor if a reasonable ($$) way to interpret the output is available.
Glad it helped! As far as the bung, you are correct in the assumption that it was centrally located to gain an "average" understanding of what was happening between the two sides and all adjustments were mirrored from one side to the other. In a perfect world. we would pull the muffler, connect a single downpipe to each side and have an AFR meter for each bank of cylinders. If I had the free time and extra funds I would make that happen, but I own an airplane... so broke as a joke haha.

As far as interpreting the output, there should be a way with a multimeter. Youll receive a signal ranging between 0 and 5V. You could linearly extrapolate the points between these voltages and correlate them to a AFR rather easily. I believe 0V is roughly 7.4 and 5V would equate to about 22.4 - I can verify these numbers for you if youd like.

In the coming weeks when I finally align and complete a few more projects ill be taking a stab at that arduino code for an AFR meter. That would be a rather small investment for everyone to make and would be a much faster means to collect data than comparing a dynamic value to a data table.

Please post up any of your progress on this and any questions. Id love to actively participate in your tuning while posting in this thread so people are able to see and read through your process in real time - I got too frustrated chasing the rabbit hole trying to figure this all out the first time to make a video that wasnt comprised of mainly curse words.

109JB, thank you for your input on this as well. Glad to see that others are noticing the same thing I am and that our data supports each others findings - overly rich in idle was a major root cause to the excessive vibrations I had at low RPM. Correcting that idle circuit had a HUGE impact on the rest of the engine tuning and starting there is 100% what I recommend to anyone that is going to be moving forward with this.

Now, looking at this thread title, I do not think its clear the information that is being shared in this thread - anyone have any suggestions as to a better thread title to get this information out to as many 912 folks as we can?