A/F vs 02 sensor voltage plot?
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A/F vs 02 sensor voltage plot?
Does anyone know the relationship between the stock O2 sensor output and the A/F reading? It seems like it should be pretty easy to ghetto rig a voltmeter to work as an a/f guage, and it cant really be less accurate than an autometer gauge.
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sure you can. it goes up and down around .45 V (above is richer, under is leaner).
But it's difficult to drive and look at a voltmeter at the same time, it's easier to look at a leds. Thats why most AF gauge use some kind of leds or bargraph.
You can build your own AF gauge easily. There are plenty of circuits described on the web.
Hugues -
But it's difficult to drive and look at a voltmeter at the same time, it's easier to look at a leds. Thats why most AF gauge use some kind of leds or bargraph.
You can build your own AF gauge easily. There are plenty of circuits described on the web.
Hugues -
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There are alot of pages on how to build a/f guages, but I haven't been able to find one which relates voltages to actual a/f ratios. The closest was this page,
http://www.pelicanparts.com/techarti...el_monitor.htm but its still doesnt say much. And I assume the .45v you mentioned was for a stoichometric ratio, but is that 14.5/1 or 12.5/1 or something else?
http://www.pelicanparts.com/techarti...el_monitor.htm but its still doesnt say much. And I assume the .45v you mentioned was for a stoichometric ratio, but is that 14.5/1 or 12.5/1 or something else?
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Originally posted by incendui
And I assume the .45v you mentioned was for a stoichometric ratio, but is that 14.5/1 or 12.5/1 or something else?
And I assume the .45v you mentioned was for a stoichometric ratio, but is that 14.5/1 or 12.5/1 or something else?
AFR Gauge comparison with voltages as tested:
http://www.alltrac.net/tuning/afgauge.html
DIY AFR Gauge sites:
http://www.techedge.com.au/
http://www.diy-wb.com/
#5
trying to build a racecar
Standard O2 sensors are only accurate around 14.7 (stoic). At that AFR they put out .5V.
Once the sensor is up to operating temp it should not really be affected by changes in exhaust gas temperature.
I also don't believe it is affected by the type (octane) of gas you run... unless you've converted the car to run on Methanol or CNG, it'll be fine.
If you want to tune for max power (12.5) then you will have to get a wideband. Stock O2 sensors are crap outside of 14.7. As you can see by the graph at either end you can have a large change in AFR with no change in output voltage.
Good luck
Once the sensor is up to operating temp it should not really be affected by changes in exhaust gas temperature.
I also don't believe it is affected by the type (octane) of gas you run... unless you've converted the car to run on Methanol or CNG, it'll be fine.
If you want to tune for max power (12.5) then you will have to get a wideband. Stock O2 sensors are crap outside of 14.7. As you can see by the graph at either end you can have a large change in AFR with no change in output voltage.
Good luck
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Originally posted by Travis R
Once the sensor is up to operating temp it should not really be affected by changes in exhaust gas temperature.
Once the sensor is up to operating temp it should not really be affected by changes in exhaust gas temperature.
Originally posted by Travis R
I also don't believe it is affected by the type (octane) of gas you run... unless you've converted the car to run on Methanol or CNG, it'll be fine.
I also don't believe it is affected by the type (octane) of gas you run... unless you've converted the car to run on Methanol or CNG, it'll be fine.
Originally posted by Travis R
If you want to tune for max power (12.5) then you will have to get a wideband. Stock O2 sensors are crap outside of 14.7. As you can see by the graph at either end you can have a large change in AFR with no change in output voltage.
If you want to tune for max power (12.5) then you will have to get a wideband. Stock O2 sensors are crap outside of 14.7. As you can see by the graph at either end you can have a large change in AFR with no change in output voltage.
There is a lot of BS floating around the internet that makes people think that a widband O2 sensor will let any idiot tune an engine. This is totally false. An O2 sensor, whether narrowband or wideband, is simply a tool.
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