As said previously on measuring voltage with narrowband O2 sensors:
http://www.mx6.com/forums/showpost.p...5&postcount=11 (Running Lean Need Advice)
http://www.mx6.com/forums/showthread.php?t=153896 (A/F Question....)
http://www.mx6.com/forums/showpost.p...&postcount=103 (Vaf Hack Thread?????)
Granted it's nothing compared to an actual wideband sensor with module but should give you
an idea much better than a standard Autometer 4375 type:
Which is nothing more than a lightshow if you don't equate each light with a
theoretical A/F reading.
Most if not all narrowband sensor read as follows:
14.7:1- 0.50v
14.6:1- 0.60v
14.5:1- 0.70v
14.2:1- 0.80v
13.5:1- 0.85v
13.2:1- 0.90v
13.0:1- 0.92v
12.5:1- 0.94v
12.0:1- 0.95v
It looks like this:
In closed loop mode the ECU will monitor the O2 sensor and the voltage should be between 0.3v~0.7v. But under acceleration (open loop) the ECU will ignore the O2 sensor and switch to default maps at which point you should see voltage between 0.70v~0.96v.
You can measure this with any digital multimeter:
Then correlate the voltage readings to your fancy light show:
^ The above numbers and lights are not accurate with a narrowband and should not be considered accurate with anything but an actual wideband sensor. It's just for demonstration purposes. If you wanted to confirm accuracy you'd need a wideband and a narrowband to confirm which light correlates to which voltage. The lights on the above .gif are with an
actual wideband sensor.
Keep in mind that the transition between lean and rich with a narrowband O2 sensor is
very steep and there can be quite a difference between on voltage reading while cruising and the same or close to the same voltage WOT.
Quote:
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Originally Posted by Zeitronix
In a closed loop mode the ECU monitors the oxygen sensor output to adjust the amount of fuel required to maintain a perfect mixture, which will lead to the the best fuel economy and minimal smog pollution. The perfect mixture for gasoline engines is 14.7:1 and the equivalent oxygen sensor output is 0.5 V. The transfer function between rich and lean mixture is really steep. This is why the air/fuel meter readings will fluctuate from 0.3V to 0.7V in a closed loop operation.
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This is not meant to be hooked up and called a day. There is a BIG difference between a narrow band O2 sensor and an actual wideband. This is just to help gain some idea of what is going on, when, where, and why.
Here is the Autometer pdf file for the fancy lightshow:
http://static.summitracing.com/globa...s/atm-4375.pdf
According to their info, the gauge lights
one LED for every 50mV. This means that
theoretically you should be looking for
at least 3 green LEDS
lit for 0.85v (somewhere in the 13.5-14.0 vicinity), 4 lit for 0.90v (13.0-13.5), and 5 lit for 0.95v putting you in the 12.5~13.0:1 vicinity. Again, this is not fact and not true in all circumstance.
Quote:
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Originally Posted by Zeitronix
At a high load (acceleration), the ECU ignores oxygen sensor output and will switch to the open loop mode using default maps to determine the amount of fuel needed for a certain amount of air. The engine will run rich at a high load and the oxygen sensor output will be in a range of 0.85V to 0.96V. The higher the voltage, the richer the mixture. The oxygen senor output monitored on the air fuel meter will indicate if the engine is running lean under the load, which is very important to keep the pistons and the rod bearings happy. The open loop maps are usually poorly optimized for performance driving since the car manufacturer must take into account all manufacturing tolerances. Adding any performance modification to your car will affect the mixture so it needs to be monitored. The Air Fuel Meter is must for any true tuner.
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Basically, even though the ECU ignores the O2 sensor under load/heavy load does not mean the O2 sensor stops working. The values may change due to the stock fuel maps and the amount of fuel being injected, EGT, etc, etc etc, but the O2 sensor itself is still goign to give you a voltage reading based on heat generated.
Again, these numbers are a
guesstimate and by no means factual or a subsitute for a wideband.
Quote:
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Originally Posted by Zeitronix
Happy turbocharged engine likes to be above 0.92 under the load. Naturally aspirated cars can get away with a little leaner mixture. Stock narrow band O2 sensor is temperature dependent. If you are running closer to the edge and looking for fast responding and temperature compensated air/fuel ratio measurements you may want to look into a wideband meter.
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Here's a good pages giving more info:
http://www.aa1car.com/library/o2sensor.htm
http://www.aa1car.com/library/wraf.htm
http://www.aa1car.com/library/2004/us10438.htm
http://en.wikipedia.org/wiki/Oxygen_sensor
http://en.wikipedia.org/wiki/Air-fuel_ratio_meter
http://www.freewebs.com/air-fuel-met...n-sensors.html
http://www.forparts.com/BoswidebandO2.htm