Narrow band O2 sensor reads VERY low (lean) on woodgas

General Discussion
#1

I have a Chinese JXQ-10 stratified downdraft system (no nozzles) which uses water for cooling and filtration. So, yes I am a weirdo. Anyway---- I ran my first drizzling test and learned a lot, but didn’t make a lot of good burnable gas this time. No fault of the drizzling idea, just multiple cockpit errors, etc…

here’s why I am making this post (a copy of one part of a much longer one I made on the Yahoo group):

One VERY interesting thing was that this was the first time I ran the genset on woodgas with the narrow band oxygen sensor in place and recording. When I run it on gasoline, the voltage is very steady at about 0.8 volts, even with large changes in load. But, during the few times that I got the engine running on woodgas, the O2 sensor read VERY low, at about 0.1 volts. That would be quite LEAN, wouldn’t it? I don’t know why this happens, but it is VERY repeatable. I’d like to hear the experiences of others in this regard.

This VERY lean reading persisted even as I adjusted my woodgas/air valves. During this run I collected data on all that was going on, but just showing a graph without being there to interpret it wouldn’t be very useful to most. If you MUST see what it looked like, you can PM me.

I know some of you are using an O2 sensor and that, hopefully some of them are narrow band.
And I don’t know if wide band sensors would read differently IN THIS CASE.
Someplace on this site there’s a video of Wayne starting up one of his trucks and “tuning” the mixture using the analog dashboard meter, and he did tune for “just right”, but that was probably a wide band sensor.
Anyway, I just don’t know if it’s just my system or what—

Pete Stanaitis

#2

Normally on these trucks you can make the mixture as rich or lean as you like. Now woodgas does like to be a bit lean, the SunPro’s with 7 or so bars will have one or two lit on the lean side when set for the Dakotas.

If you can’t richen the mixture then I’d check for air leaks or gasifier plugging. If you can tell by the engine sound that it’s richening up (choking on gas) and it still reads lean, I’d suspect the AFR meter.

EDIT: Wayne and many of us are using narrowband O2 gauges. They come stock on most vehicles, so it makes sense. Wideband is a pricey option, but some folks have indeed got them.

#3

Thanks for your input, Chris.
Regarding your comment about a possibly bad AFR:
I am not using an AFR gage on my current setup. I am directly reading/recording voltage on my Arduino Datalogger. So, what you see is what you got.
By the way, it is nice to be recording the O2 sensor’s output because I can see the sensor values fluctuating almost aimlessly as it is heating up and cooling down when the engine goes on and off. Now I can really understand why the engine’s ECU (or whatever they call it) has to account for this.

Pete Stanaitis