Air/Fuel Monitor

[Erik Quackenbush]

When I put an A/F meter in my TR6 I started with a bar graph LED display 
like you but I later switched to an analog gauge from Westach 
(http://www.westach.com) which I find MUCH easier to read in bright 
sunlight. The other problem I had with the LED display is that it changed 
so quickly that I spent too much time looking at it and not enough looking 
at the road. The needle on my analog gauge moves slowly and give me a much 
better idea of my average A/F ratio at idle and cruise. I suppose you could 
put a low pass filter on the input to the LED display for the same effect 
but the needle gauge looks right at home under my dash.

For a much more accurate A/F meter you might want to look into the 
DIY-wideband O2 sensor project from the DIY-EFI 
(http://www.diy-efi.org/diy_efi/projects/diy_wb/) mailing list. Standard O2 
sensors are only accurate for a small range around stoichiometric and thus 
are only useful to indicate rich or lean. A wideband sensor (found on Honda 
ultra low emission engines) is accurate
enough to tell you precisely HOW rich or lean you are but you need a 
special signal conditioning circuit to use one. I haven't built mine yet so 
I can't report any results. The 5-wire wideband sensors are expensive ($120 
and up) but some generous individuals on the DIY-EFI mailing list have 
arranged for group purchases of printed circuit boards and component kits 
for around $20 and they may have some left.

-Erik

At 07:08 AM 12/26/2001 -0500, Nelson Riedel wrote:
>I've spent much December playing with an homemade Air/Fuel Monitor.  There was
>some interest when mentioned on the 6PACK list last week so passing it on
>here.  Some of you in the north might find it a good winter project. Details
>are on Buckeye Triumphs website for anyone interested. The link below goes to
>the Buckeye Triumphs Technical page.  Scroll down to the area on TR250/TR6
>carbs then click on "Air/Fuel Monitor" or "Using Air/Fuel Monitor"
>
>  http://www.buckeyetriumphs.org/index_technical.htm
>
>Have fun

--
Erik Quackenbush, Midwest Filter Corporation 
1-847-680-0566  http://www.midwestfilter.com

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