HarleyTechTalk

It's an avalanche sensor. Or switching sensor. When it reads above stoich it goes one way, below it goes the other. That is why Bosch calls it a switching sensor. See my post above.

QuoteBut the sensor is doing the switching.

No it is not!
The ECU is doing the switching.
Read and understand also the text in the link to Bosch.

QuoteStandard narrow band type Oxygen Sensors operate between 0 and 1 volts, and are only capable of accurately measuring a stoichiometric air/fuel ratio (e.g. 14.7:1). A richer or leaner condition results in an abrupt voltage change and is only useful for qualitative determination. Modern automobiles use "switch" like sensing at idle and part throttle to make small compensations in fuel delivery to keep the air/fuel ratio near 14.7:1.

QuoteA richer or leaner condition results in an abrupt voltage change and is only useful for qualitative determination.

That mean that the 02 sensor is reporting a constant voltage of 0.450 V at stoich combustion.
Anything leaner or richer will result in 1v or close to zero V.

"switch like sensing" from the text above is the strategy used (by the ECU) and mean that the fuel correction shown at the bottom small graph is what is done to achieve the sine wave voltage from the o2 sensor shown on the graph above.

The ECU is doing all the fuel control, not the sensor.
The sensor is forced to switch 0-1-0-1... volt due to the actions of the ECU.

Quote from: ultraswede on April 06, 2013, 12:18:16 AM

QuoteBut the sensor is doing the switching.

No it is not!
The ECU is doing the switching.
Read and understand also the text in the link to Bosch.

QuoteStandard narrow band type Oxygen Sensors operate between 0 and 1 volts, and are only capable of accurately measuring a stoichiometric air/fuel ratio (e.g. 14.7:1). A richer or leaner condition results in an abrupt voltage change and is only useful for qualitative determination. Modern automobiles use "switch" like sensing at idle and part throttle to make small compensations in fuel delivery to keep the air/fuel ratio near 14.7:1.

QuoteA richer or leaner condition results in an abrupt voltage change and is only useful for qualitative determination.

That mean that the 02 sensor is reporting a constant voltage of 0.450 V at stoich combustion.
Anything leaner or richer will result in 1v or close to zero V.

"switch like sensing" from the text above is the strategy used (by the ECU) and mean that the fuel correction shown at the bottom small graph is what is done to achieve the sine wave voltage from the o2 sensor shown on the graph above.

The ECU is doing all the fuel control, not the sensor.
The sensor is forced to switch 0-1-0-1... volt due to the actions of the ECU.

Yes the ECM does the fuel control based on the voltage it receives from the sensor which SWITCHES from <450mv> depending on how much fuel is added or removed by the ECM

All the sensors do is report a voltage <450mv> and the ECM adds/remnoves the fuel and then polls the sensor to see if switched from <450mv>

Argue all you want that is how I read the Bosch text and understand the Harley ECM and have no trouble tuning............

Consider this:
O2 voltage is basically a 0-1v output sensor. Assigning 450mv to as a reference is exactly that.. a reference point used to determine AFR @ ~14.7 for gasoline..
Look at the wave form. Do you see any switching going on?
The sensor does absolutely nothing but generate a voltage.
The 450mv switch is nothing more than a fueling adjustment point. If either higher or lower voltage than the reference point.
If we were to use 600mv in lieu of 450mv would the sensor then switch at 600mv? How 'bout 780mv?
Bob

The sensor voltage swings in reaction to 02 content that the ECM has created with its fuelling, the ECM does not monitor the sensor voltage continuously, rather it samples the voltage at a programmed stage of the combustion cycle(switching) to see if the 02 content is where it expects it to be, it adds or subtracts fuel based on that finding + all the other info it is gathering from the other sensors to keep the AFR in check.....well that's how I thought it worked, happy to be corrected as that's what this section is all about.

Quote from: FLTRI on April 06, 2013, 01:13:55 AM
Consider this:
O2 voltage is basically a 0-1v output sensor. Assigning 450mv to as a reference is exactly that.. a reference point used to determine AFR @ ~14.7 for gasoline..
Look at the wave form. Do you see any switching going on?
The sensor does absolutely nothing but generate a voltage.
The 450mv switch is nothing more than a fueling adjustment point. If either higher or lower voltage than the reference point.
If we were to use 600mv in lieu of 450mv would the sensor then switch at 600mv? How 'bout 780mv?
Bob

Well Bob you obviously have not read the Bosch documents (or fail to understand them) that your buddy SC used to put up quite regularly.

Bosch designed them and know how they work and call them switching sensors.........good enough for me

Perhaps you should contact Bosch and get them to explain to you why they call them switching sensors as you obviously won't believe anyone here.

I think switching sensor is more of a term for it's operation rather than the sensor itself. Switching has to come from the ecm or it would just sit there at a constant voltage.
Ron

Bob,..... Scotty, et al, has this correct.  I HAVE read what SC had to say.  There is more than one type of 'switch'.  Most think of a switch as a wall switch, either on, or off.  But in 'controls' work, there is also the threshold of the device the switch is attached to.  It works as a TEAM, just like the light switch controls a ceiling fan.  ALL electronics use threshold amounts of voltage.  There is NO true 'on' and no true 'off'.  There is 'low' and 'high'.  There IS a difference.  There will always be leakage voltage present.  Leakage voltage doesn't matter, what matters is the threshold voltage in the transistor.  This is ALL about how DC current works and how a sensor reports.

There are TWO types of photo eyes for example.  Transistor based or has an actual microswitch inside.  The one with a switch will leak a very small amount of voltage, the transistor based ones WILL leak appreciable amounts of voltage.

ANYTHING that is even loosely transistor based works in this manner.  Our ECM has chips, etc inside, so it also works on 'transistor' theories.  Low and High.  NOT off and on.

This type of switch works like this.  Most think a light bulb attached (or a VOM) to a sensor would see the light go off and on, if it was a switch.  In reality, the light will go really dim, to really bright.  Why?  It is hitting the gate  on the transistor(inside of the ECM) making the 'transistor' turn off and on.  Switching sensors turn on and off the transistor attached.  It is a system and THAT is the why it is called a switching sensor as it 'switches' the attached transistor on and off.  The transistor inside turns on and off.  THAT is where the sensor is reporting... after the attached transistor.  If one could hook up that light bulb to the opposite side of the transistor...  the light WOULD turn on and off.

This IS basic 'controls' theory and is the how all kinds of machines work.  Photo-eyes, proximity switches, etc all work in this manner.  A sensor does NOT live in a vacuum.  It IS what that sensor is hooked up to, to call it a 'switch' or a device that measures voltage (analog voltage device).  A switch looks like the voltage characteristics of a narrow band.  Exactly.  This IS a 'switch' when working with controls, whether they be on a vehicle or a piece of machinery that MAKES the vehicle.  It IS a digital switch.

True voltage representations are the graphs from Wide Bands.  That graph is really quite linear and works on a 0 to 5 volt system.  0 to 1 is a switching voltage.  For the application, it's a switch, because NOTHING is in a vacuum, Ron.  It depends on what it is hooked up to, and THAT (what something is hooked up to) is what is 'termed' a switch or not.

The ECM does NOT throttle around a voltage.  Doesn't.  Wide band controllers do that.  Scotty IS knowledgeable on this subject, BTW.  Our NB sensors ONLY report low and high, and NOT the voltage present.  WHile the ECM 'warbles' the fuel  low to high to low to high (PID Controls)  all it really is doing is going to report low AFR, high AFR, low AFR, etc.  The bias in CLBs etc just alter where the switching point, in the ECM is received at.  It works on PID, so if it reads HIGH when commanded LOW, the ECM compensates fuel delivery to make what IS to what is EXPECTED.

The actual 'switch' is whatever the attached transistor says it is ON or OFF. between the two, the sensor reports to the transistor (the WHOLE 'switch")  and we change THAT voltage... the amount of leak before the transistor 'sees' the voltage to change state.

Yes Ron, you ARE correct!!!!  The ECM warbles the fuel while going down the road.  The sensor reports back lean or rich.  Just those two 'answers'  NOTHING else.  It does NOT read voltage, it IS a digital switch.

The 'switch', by itself is NOTHING.  It would be a light switch WITHOUT that ceiling fan.  It is ALWAYS about the system as a whole.  AND... 'terminology' is ALWAYS based upon the application and not what you or I think.

A few years ago, I stumbled around with this crap and how it works on controls, until I learned how to think about it all.  All of this low/high BS is confusing, until I learned to call the system as a whole the 'actual' switch.  Our O2 sensors, by themselves, do NOT make any kind of switch at all.  Think of this as a 'switch' that has two, separated, components.  Until that transistor inside the ECM, or PLC, or whatever, switches... there is nothing.  On a cheap ass PLC running 24vdc, the switching voltage (from 'on to off') can be as high as 14vdc!  Everything is made to go 'low to high' at a lower voltage as that.

In our application...  it IS a switching function...  simply High to Low.  The sensor, ANY sensor is simply made to react with whatever it is that senses the sensor.  Like the turning on or off a gate in a transistor or chip.

Ron, try this, as I am curious... instead of just heating a NB sensor and measuring voltage, also introduce some oxygen into a chamber.  Weld up an old pipe we could screw a sensor into, along with a bung we could introduce oxygen.  Remember this crap measures the DIFFERENCE in oxygen in the chamber, and without the chamber.  That difference IS the O2, what the sensor reads.

Besides keeping the operator safe... we all like the best fresh air as possible on a dyno, because we wish to have the 'reference' air of the sensor to be CLEAN air, right?

Quote from: Coyote on April 05, 2013, 07:29:48 PMWhen it reads above stoich it goes one way, below it goes the other.

You mean, like a switch? 

Quoteit IS a switching function...  simply High to Low

Yes agree, it could be. BUT it its the ECM that move the AFR up or down, causing the sensor to "switch"
NOT the sensor switching by its own.

IF the sensor is doing the switching, how do you then explain that the switching frequency follow Rpm up or down?
The sensor just sits in the exhaust stream and no nothing about Rpm.

Quote from: wurk_truk on April 06, 2013, 07:54:23 AM
Yes Ron, you ARE correct!!!!  The ECM warbles the fuel while going down the road.  The sensor reports back lean or rich.  Just those two 'answers'  NOTHING else.  It does NOT read voltage, it IS a digital switch.

The 'switch', by itself is NOTHING.  It would be a light switch WITHOUT that ceiling fan.  It is ALWAYS about the system as a whole.  AND... 'terminology' is ALWAYS based upon the application and not what you or I think.

A few years ago, I stumbled around with this crap and how it works on controls, until I learned how to think about it all.  All of this low/high BS is confusing, until I learned to call the system as a whole the 'actual' switch.  Our O2 sensors, by themselves, do NOT make any kind of switch at all.  Think of this as a 'switch' that has two, separated, components.  Until that transistor inside the ECM, or PLC, or whatever, switches... there is nothing.

In our application...  it IS a switching function...  simply High to Low.  The sensor, ANY sensor is simply made to react with whatever it is that senses the sensor.  Like the turning on or off a gate in a transistor or chip.

Ron, try this, as I am curious... instead of just heating a NB sensor and measuring voltage, also introduce some oxygen into a chamber.  Weld up an old pipe we could screw a sensor into, along with a bung we could introduce oxygen.  Remember this crap measures the DIFFERENCE in oxygen in the chamber, and without the chamber.  That difference IS the O2, what the sensor reads.

Besides keeping the operator safe... we all like the best fresh air as possible on a dyno, because we wish to have the 'reference' air of the sensor to be CLEAN air, right?

Not sure anything would change in this test. There would be no switching going on. Isn't this event (high/low needed to determine what O2 content the sensor sees from a base line clb?
Pretty sure all I would see is the voltage come up to 1mv and stay there with or without additional oxygen.
Ron

You guys are arguing semantics however the industry correct terminology is that the narrow band O2 sensor is a switching sensor. Without a closed loop system, both the switch and ECM outputs would rail and neither would move.

In this application, the ECM provides the integration of the error signal and loop correction. The sensor provides the error signal, either high or low (switching) depending on O2 content.

Quote from: ToBeFrank on April 06, 2013, 08:00:24 AM

Quote from: Coyote on April 05, 2013, 07:29:48 PMWhen it reads above stoich it goes one way, below it goes the other.

You mean, like a switch? 

Quote from: ToBeFrank on April 06, 2013, 08:00:24 AM

Quote from: Coyote on April 05, 2013, 07:29:48 PMWhen it reads above stoich it goes one way, below it goes the other.

You mean, like a switch? 

Yep. Any voltage change can be called a switch.
The misnomer is calling the sensor a switch as in "switching sensor".
Consider this: LSU4 broadband and most all sensors, for that matter, are just as much a switching sensor as a narrow band used for stoich and/or making other decisions based on crossing a line. Ie: heat management. The head sensor acts just like a "switching sensor", right?
Bob

Widebands are not the same as the provide a substantially linear change of voltage to afr. Narrow band provide a step change.



If you won't believe Bosch when they refer to it as a switching sensor, how about Delphi?

http://delphi.com/manufacturers/auto/sensors/engine-and-transmission/gasoline/mini-switching-oxygen/

Bob Bob Bob, you do NOT get it at all.

You guys are NOT getting it.  a NB sensor is a switch and ALL the ECM detects is the state of the switch.  Forget about what the damn sensor does, it is a TWO part sensor... the sensor AND the transistor inside make for the WHOLE switch.  Once more...  THE SENSOR ITSELF IS NOT THE COMPLETE SWITCH.  You argue semantics and gave no understanding here.  In Electronic controls, it IS the ECM that determines what the activity does.  Why do you guys argue this?

A WB, OTOH, is an analog sensor.  It reads from 0vdc to 5vdc.  This is the WHY there is a damn slope, Guys!  This sensor does NOT go to a transistor, it goes to an analog voltage reading circuit.  It is WHY these devices need a WEGO UEGO, etc.  THAT WEGO is THE controller that converts the WBs signal to 0-5vdc.

NBs are digital and wide bands are analog.  If this all beyond you to understand?  Just take it as a fact.  Inputs on a PLC are the same way.  One can denote, thru software, whether a switch is digital (and on some what voltage is the tipping point), analog READS 0-5vdc and each increment of that system can be programmed for a different result.

You guys THINKING a switching sensor is an analog sensor does NOT make it so.

I give up now.  It is simply beyond your level of expertise.  I recommend reading on analog switching and digital switching on the internet.  ANd NOT revolving around O2 sensors.  You need a background to this.

Our ECM does NOT 'read' and react on the voltages of the NB switches.  It is simply a go/ no go device.  We DO set the point of go or no go, but ALL it friggin reads is either lean or rich.  It is a switch.  CLB IS the tipping point of the switch.  We alter the tipping point of the transistor to alter what is nominal voltage.

A WB with controller will read HOW rich and HOW lean the O2 concentration of the gas really is.  HUGE difference between the two.

If you ARE having problems with this...  you do NOT understand exactly HOW a PID circuit works.

Like me with certain mechanical stuff.  I need to ask and listen, you guys ask, don't accept the answers and argue instead.

Done.
Sensors 101.

I found this, and it starts to make sense even for a retard like me. Plus John won't need to yell at me any more.
http://www.autoshop101.com/forms/h37.pdf
Covers how 02 effects the voltage and what play the ecm has in the picture. Yes it is a switching sensor.
Ron

NOT yelling nat you... today.  Yelling at BOB,

It is either above or below 450mv ie on or or off ...clb changes where the "450" sits.....got it. yeh?

Here is a shot from a Vtune cut down to 10 seconds, clb set @ 450 notice the O2 sensor mv being driven rich to lean from around 700 to 40 nothing constant always moving up or down also injector BPW coincides with it (easier to see if not blown up so much) but appears the BPW increases and then the sensor shows richer then BPW decreases and sensors mv begins to drop.


[attachment removed after 60 days by system]

Quote from: wurk_truk on April 06, 2013, 11:27:00 AM
Bob Bob Bob, you do NOT get it at all.

You guys are NOT getting it.  a NB sensor is a switch and ALL the ECM detects is the state of the switch.  Forget about what the damn sensor does, it is a TWO part sensor... the sensor AND the transistor inside make for the WHOLE switch.  Once more...  THE SENSOR ITSELF IS NOT THE COMPLETE SWITCH.  You argue semantics and gave no understanding here.  In Electronic controls, it IS the ECM that determines what the activity does.  Why do you guys argue this?

A WB, OTOH, is an analog sensor.  It reads from 0vdc to 5vdc.  This is the WHY there is a damn slope, Guys!  This sensor does NOT go to a transistor, it goes to an analog voltage reading circuit.  It is WHY these devices need a WEGO UEGO, etc.  THAT WEGO is THE controller that converts the WBs signal to 0-5vdc.

NBs are digital and wide bands are analog.  If this all beyond you to understand?  Just take it as a fact.  Inputs on a PLC are the same way.  One can denote, thru software, whether a switch is digital (and on some what voltage is the tipping point), analog READS 0-5vdc and each increment of that system can be programmed for a different result.

You guys THINKING a switching sensor is an analog sensor does NOT make it so.

I give up now.  It is simply beyond your level of expertise.  I recommend reading on analog switching and digital switching on the internet.  ANd NOT revolving around O2 sensors.  You need a background to this.

Our ECM does NOT 'read' and react on the voltages of the NB switches.  It is simply a go/ no go device.  We DO set the point of go or no go, but ALL it friggin reads is either lean or rich.  It is a switch.  CLB IS the tipping point of the switch.  We alter the tipping point of the transistor to alter what is nominal voltage.

A WB with controller will read HOW rich and HOW lean the O2 concentration of the gas really is.  HUGE difference between the two.

If you ARE having problems with this...  you do NOT understand exactly HOW a PID circuit works.

Like me with certain mechanical stuff.  I need to ask and listen, you guys ask, don't accept the answers and argue instead.

Done.
Sensors 101.

a rose is a rose.  You explained it well.

Quote from: Hilly13 on April 06, 2013, 02:48:59 PM
It is either above or below 450mv ie on or or off ...clb changes where the "450" sits.....got it. yeh?

Yes Hilly.  And our CLB simply alters that 450mv switching point and nothing else.

YOU are MY Dude!

Wurk  cheers

Quote from: wurk_truk on April 06, 2013, 12:56:22 PM
NOT yelling nat you... today.  Yelling at BOB,

No need to YELL!
In the early days before wide bands we would send the exhaust system and narrow bands ("switching") sensors to the engine builder. He would dial in the best performance mixture on the engine Dyno to...say 12.8:1. Then take the reading from the o2 sensor (usually ~870-890mv IIRC). Then we monitored the sensor output and readjusted fueling to keep within that voltage target.
Was it perfect? No but,it was certainly better than trying to read plugs after idling back into the pits. Lol
Sorry if I don't see anywhere in or on the sensor a switch...just a voltage output that the ECM then switches the fueling to either richer or leaner than the reference point.
I have no theory of operation or a plethora of technical terms to back up my personal observations.
My only experience is from actually using these sensors for other than a switch from Stoich.
Please take a moment to take another look at the sine wave (not square wave) Bosch graph of the "switching" sensor Coyote offered. That does not appear to be switching anything just reporting voltage increases and decreases as the ECM commands fueling changes.
Bob
PS- Yelling and personal digs and insults will not change the fact these narrow band sensors have no switching ability whatsoever...just variable voltage output...it is the ECM that switches.

Quote from: FLTRI on April 06, 2013, 04:27:05 PM

Quote from: wurk_truk on April 06, 2013, 12:56:22 PM
NOT yelling nat you... today.  Yelling at BOB,

No need to YELL!
In the early days before wide bands we would send the exhaust system and narrow bands ("switching") sensors to the engine builder. He would dial in the best performance mixture on the engine Dyno to...say 12.8:1. Then take the reading from the o2 sensor (usually ~870-890mv IIRC). Then we monitored the sensor output and readjusted fueling to keep within that voltage target.
Was it perfect? No but,it was certainly better than trying to read plugs after idling back into the pits. Lol
Sorry if I don't see anywhere in or on the sensor a switch...just a voltage output that the ECM then switches the fueling to either richer or leaner than the reference point.
I have no theory of operation or a plethora of technical terms to back up my personal observations.
My only experience is from actually using these sensors for other than a switch from Stoich.
Please take a moment to take another look at the sine wave (not square wave) Bosch graph of the "switching" sensor Coyote offered. That does not appear to be switching anything just reporting voltage increases and decreases as the ECM commands fueling changes.
Bob
PS- Yelling and personal digs and insults will not change the fact these narrow band sensors have no switching ability whatsoever...just variable voltage output...it is the ECM that switches.

Didn't read my link , did you? Explains it well.
Ron