How does the O2 sensor work/E10=crap mpg
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Joined: Mar 2003
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From: Nampa Id
How does the O2 sensor work/E10=crap mpg
Who knows EMPIRICLY in regards to an O2 sensor:
How does it read O2?
What happens to O2 in ethanol when combusted?
How does the sensor know the diff between added O2 and ambient O2?
How does the ECU, any ECU figure it out?
Does any of this make sense?
People are talking alot of crap, I'm looking for the truth.
I'm a mech. engineer, not a chemist/physics guy.
I continue to get poor milage beyond the "BTU content", and even the % difference. Add to that a crapshoot of 'real%'(it varies 5-15% I've tested it) its just BS.
It's like this on many cars, old, new, injected, carbs.!?!?!?
Someone please enlighten my dumba@@
How does it read O2?
What happens to O2 in ethanol when combusted?
How does the sensor know the diff between added O2 and ambient O2?
How does the ECU, any ECU figure it out?
Does any of this make sense?
People are talking alot of crap, I'm looking for the truth.
I'm a mech. engineer, not a chemist/physics guy.
I continue to get poor milage beyond the "BTU content", and even the % difference. Add to that a crapshoot of 'real%'(it varies 5-15% I've tested it) its just BS.
It's like this on many cars, old, new, injected, carbs.!?!?!?
Someone please enlighten my dumba@@
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
Basically it measures the oxygen differential from the exhaust to the atmosphere, and varies a voltage based on that. I don't see why E10 or any fuel would make a difference in that.
What exactly is the problem you are having?
What exactly is the problem you are having?
Thread Starter
Advanced
Joined: Mar 2003
Posts: 90
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From: Nampa Id
Thanks A40
No real problem, just lower mpg.
I suspect richer fuel due to more O2(lean) ECU read.
Not a car problem, but a natural resource nightmare. Depending of course on the real time average of all the E10/Blended fuel users.
Trying to get the ducks in a row before calling
I suspect richer fuel due to more O2(lean) ECU read.
Not a car problem, but a natural resource nightmare. Depending of course on the real time average of all the E10/Blended fuel users.
Trying to get the ducks in a row before calling
Pro
Joined: Jul 2002
Posts: 703
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From: Milwaukee Wi
my understanding it the 02 sensor just reports stoich regardless of the fuel. So E10 vs traditional unleaded fuel end result is that ECU get feed back and you have proper A/F and complete burn. Not uncommon to see poorer gas mileage. E85 mileage is poorer yet.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
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From: The Motor City
first of all, ALL alternative fuels burn or have a different lambda or AFR. E85 for example w/86% ethanol is approx. 9.76 AFR which would be VERY rich, as stock would be 14.73:1 w/premium pump gas.
If the stock sensors can even deal w/it, your AFR using this fuel should be wacked. DO not go by a scanner reading it will only tell you what the ECM is programmed to attain as an AFR. You will need a real AFR meter to know the actual Lambda or AFR. From there to get it to work well, the AFR in C.L. and OL will need to be changed. I have not tried switching to alternative fuels, but this will require some work in the tune (memcal of ecm)w/the appropriate software, laptop, and afr meter.
If the stock sensors can even deal w/it, your AFR using this fuel should be wacked. DO not go by a scanner reading it will only tell you what the ECM is programmed to attain as an AFR. You will need a real AFR meter to know the actual Lambda or AFR. From there to get it to work well, the AFR in C.L. and OL will need to be changed. I have not tried switching to alternative fuels, but this will require some work in the tune (memcal of ecm)w/the appropriate software, laptop, and afr meter.
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
Got this from Wikipedia... article on "Oxygen Sensor"
The sensor element is a ceramic cylinder plated inside and out with porous platinum electrodes; the whole assembly is protected by a metal gauze. It operates by measuring the difference in oxygen between the exhaust gas and the external air, and generates a voltage or changes its resistance depending on the difference between the two. The sensors only work effectively when heated to approximately 800°C (1,472F), so most newer lambda probes have heating elements encased in the ceramic to bring the ceramic tip up to temperature quickly when the exhaust is cold. The probe typically has four wires attached to it: two for the lambda output, and two for the heater power, although some automakers use a common ground for the sensor element and heaters, resulting in three wires. Earlier non-electrically-heated sensors had one or two wires.
[edit] Operation of the probe
[edit] Zirconia sensor
The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. An output voltage of 0.2 V (200 mV) DC represents a lean mixture. That is one where the amount of oxygen entering the cylinder is sufficient to fully oxidize the carbon monoxide (CO), produced in burning the air and fuel, into carbon dioxide (CO2). A reading of 0.8 V (800 mV) DC represents a rich mixture, one which is high in unburned fuel and low in remaining oxygen. The ideal point is 0.45 V (450 mV) DC; this is where the quantities of air and fuel are in the optimum ratio, called the stoichiometric point, and the exhaust output mainly consists of fully oxidized CO2.
The voltage produced by the sensor is so nonlinear with respect to oxygen concentration that it is impractical for the electronic control unit (ECU) to measure intermediate values - it merely registers "lean" or "rich", and periodically adjusts the fuel/air mixture to keep the output of the sensor alternating between these two states. The time period chosen by the ECU to monitor the sensor and adjust the fuel/air mixture creates an inevitable delay, which makes this system less responsive than one using a linear sensor (see below). The shorter the time period, the higher the so-called "cross count" [1] and the more responsive the system.
The zirconia sensor is of the 'narrow band' type, referring to the narrow range of fuel/air ratios to which it responds.
So - to adjust (if it were just that simple) for a different Fuel, or mixture like E10 or E85 even, with a different "ideal" stoichiometric air/fuel ratio, you need to change the voltage reading that the ECM is looking for as it's "crossover point" for the cross counts - the Target voltage, in other words. Ought to be do-able...
Or shift the voltage output of the sensor up/down as you desire between the sensor and the ECM, exxentially "lying" to the ECM about what the Actual sensor voltage is.. That sort of circuit shouldn't be hard to come up with either, although for me at least it seems simpler to edit the PROM or Memcal file to fix it There.
The sensor element is a ceramic cylinder plated inside and out with porous platinum electrodes; the whole assembly is protected by a metal gauze. It operates by measuring the difference in oxygen between the exhaust gas and the external air, and generates a voltage or changes its resistance depending on the difference between the two. The sensors only work effectively when heated to approximately 800°C (1,472F), so most newer lambda probes have heating elements encased in the ceramic to bring the ceramic tip up to temperature quickly when the exhaust is cold. The probe typically has four wires attached to it: two for the lambda output, and two for the heater power, although some automakers use a common ground for the sensor element and heaters, resulting in three wires. Earlier non-electrically-heated sensors had one or two wires.
[edit] Operation of the probe
[edit] Zirconia sensor
The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. An output voltage of 0.2 V (200 mV) DC represents a lean mixture. That is one where the amount of oxygen entering the cylinder is sufficient to fully oxidize the carbon monoxide (CO), produced in burning the air and fuel, into carbon dioxide (CO2). A reading of 0.8 V (800 mV) DC represents a rich mixture, one which is high in unburned fuel and low in remaining oxygen. The ideal point is 0.45 V (450 mV) DC; this is where the quantities of air and fuel are in the optimum ratio, called the stoichiometric point, and the exhaust output mainly consists of fully oxidized CO2.
The voltage produced by the sensor is so nonlinear with respect to oxygen concentration that it is impractical for the electronic control unit (ECU) to measure intermediate values - it merely registers "lean" or "rich", and periodically adjusts the fuel/air mixture to keep the output of the sensor alternating between these two states. The time period chosen by the ECU to monitor the sensor and adjust the fuel/air mixture creates an inevitable delay, which makes this system less responsive than one using a linear sensor (see below). The shorter the time period, the higher the so-called "cross count" [1] and the more responsive the system.
The zirconia sensor is of the 'narrow band' type, referring to the narrow range of fuel/air ratios to which it responds.
So - to adjust (if it were just that simple) for a different Fuel, or mixture like E10 or E85 even, with a different "ideal" stoichiometric air/fuel ratio, you need to change the voltage reading that the ECM is looking for as it's "crossover point" for the cross counts - the Target voltage, in other words. Ought to be do-able...
Or shift the voltage output of the sensor up/down as you desire between the sensor and the ECM, exxentially "lying" to the ECM about what the Actual sensor voltage is.. That sort of circuit shouldn't be hard to come up with either, although for me at least it seems simpler to edit the PROM or Memcal file to fix it There.
