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Discussion Starter #1 (Edited)
Simple question:

Would this cheapo Air/Fuel gauge:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-G2986&N=700+4294925228+4294925227+4294822093+4294908392+115&autoview=sku

give me an accurate reading if I used a heated O2 sensor stuck up the tailpipe?

I just need something cheap and portable that I can use to tune my F100 and 73 Vert without having to do the ole "drive, read plugs, adjust carb, drive, read plugs, adjust carb, drive, read plugs ad nauseam..."

Everything I’m finding that uses the “in the tailpipe probe” is an exhaust gas analyzer and WAY more than I need.

I’m also open to suggestions!! :thumbsup:

And as a second question: Can the heating element in a O2 sensor even be turned on and left on for an extended amount of time or will it burn out?
 

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I am certainly not an expert, but here is my understanding of HEGO's.

Basically the sensor is either 0volts or 1.4 (or so) volts. and it toggles back and forth really quickly, making roughly a square wave. You would need some kind of circuit to integrate that squarewave to get a meaningful output.

Some cars have a wideband O2 sensor which gives a reading which is more or less analog.

So the normal HEGO sensor only gives either "too rich" or "too lean" information, and the wideband O2 sensor, which gives an analog reading.

I'd bet your gauge needs a wideband sensor. They are a lot more expensive.

_That_ is the sum total of everything I know about O2 sensors.
 

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the one thing you can do with a narrowband O2 and that gauge, is tune for ONLY 14.64:1 A/F ratio.....when the HEGO output reads 0.45-0.50VDC, then that is stoich for gasoline.....above and below this voltage cannot and should not be extrapolated to determine any sort of "leanness" or "richness"...so technically, you dont even need that gauge....all you would need at least is a multimeter to monitor the voltage output of the O2

if you need some sacrificial O2s, i got my old bosch ones that i took out to replace with NTKs
 

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Discussion Starter #4
the one thing you can do with a narrowband O2 and that gauge, is tune for ONLY 14.64:1 A/F ratio.....when the HEGO output reads 0.45-0.50VDC, then that is stoich for gasoline.....above and below this voltage cannot and should not be extrapolated to determine any sort of "leanness" or "richness"...so technically, you don’t even need that gauge....all you would need at least is a multimeter to monitor the voltage output of the O2

If you need some sacrificial O2s, I got my old bosch ones that I took out to replace with NTKs
Yeah, that's all I wanting; just something to get me in the ballpark during cruise. And not have to weld in a bung on two vehicles that I’ll be changing the exhaust on in the future… :D

But my main concern is the location. Is the exhaust still hot enough for the O2 to read correctly if it is all the way in the back in the tailpipe? From http://www.asashop.org/autoinc/dec2002/mech.htm "572 degrees Fahrenheit to 680 degrees". And can the heater be turned on constantly or will it burn out.

Actually found the answer on the same page… :D
Since OBD-II vehicles may have multiple oxygen sensors located some distance from the engine exhaust ports, these sensors are generally heated to speed the warm-up time period. The HO2S incorporates an internal electric heating element to bring the O2 sensor up to operating temperature quickly (under 35 seconds). Internal heating elements usually operate continuously while the engine is running to maintain an operating temperature of approximately 1292 degrees Fahrenheit to 1472 degrees Fahrenheit. Heated O2 sensors operate at a more consistent temperature and allow greater flexibility of placement locations in the exhaust system.
I’ll PM you about the O2. I have some but they all have 100K+ miles on them…
 
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