Tuners! Help me understand 02 sensor voltages

[07heri]

I'm trying to grasp an understanding of how to interpret 02 sensor voltages.  After hours of reading I keep seeing explanations saying that the voltages should fluctuate above and below whatever the set point of the sensor or CLB.  Most seems pretty theoretical but haven't found any real world examples to look at.  I understand the rich lean rich lean around the CLB idea.  But I would like to learn how to interpret the logged voltages.

After your finished with a tune what should someone see for 02 voltages if datalogged?  Can someone post a log and an explanation of what's happening.

[z00t]

This might help:
http://harley.uk.net/doku.php?id=tech:espfi:fueling

[07heri]

This might help:
http://harley.uk.net/doku.php?id=tech:espfi:fueling

Good reading material, thanks.  So in a well-tuned bike the 02 readings should stay a couple hundred above or below 450?  Should the voltages stay within that range?  Even in a well-tuned bike will the voltages fluctuate outside of that renage?  If so, what causes it?  I guess I'm most curious about what the voltages look like like on a well tuned bike versus a mediocre tuned bike versus a poorly tuned bike.  And, how to interpret the voltages.

[rigidthumper]

In closed loop, the ECM will drive the mixture rich, check that it went the way it was commanded, then drive lean, check to ensure compliance, and repeat the process a zillion times over (as long as you're still in the closed loop area).
If you're in open loop, then the 02 voltage should remain very stable unless/untill something breaks/wears out.

[rageglide]

Closed loop and Lambda (vs AFR) would also accommodate for Fuel type due to the voltage change.

Quesion, Can a NB O2 also provide feedback regarding fuel quality when in Open loop?  Example, running 10% ethanol vs 100% gasoline.  I always assumed the sensor is ignored while open loop...

[wolf_59]

I could never find any setpoints as to how far above or below my 447 CLB setting the ecm would drive the readings, but 680 was the I say average for the high readings and low readings were any where from 280 to 20.
I quit  and trusted the system did my tunes set clb's back to original and set open loop areas to my liking, installed a digital AFR meter and checked my tune everything was spot on for what the ecm was calling for  closed loop areas ran between 14.5 down to 14.3 constantly fluctuating the best I can remember and open loop 13.2 

[attachment removed after 60 days by system]

[07heri]

Correct where my assumptions are wrong:

1)  The sensor can read from 1 volt to 5 volts

2)  It will read way high during warm up.  How much higher?

3)  Once both fire off they should fluctuate higher and lower around .450 (CLB).  How much swing would be considered normal?

4)  This fluctuation should remain in idle, steady state, or anytime in CL. 

5)  Accel or decel should go rich with higher readings, and stay higher until CL kicks back in

6)  IDLE:  Voltages should fluctuate in CL.  OL voltages will remain steady at whatever the sensor
is reading.  I wasn't sure if the sensor still reads and responds, and the ECM just doesn't acknowledge it.  Or if the sensor was totally offline.

7)  If VE's are way off to the high side the sensor may never have a chance to toggle below .450.  How
does the ECM handle this?  Does it keep trying to reduce fuel every polling cycle?  What happens if the ECM can't get below .450? 

[rageglide]

The Narrow Band sensor Outputs between .02 and .08 V.   It doesn't read Voltage.   Voltage supplied to the O2 sensor is there to power the heater circuit.  Heated O2's exist because you can go Closed loop sooner than an unheated O2 sensor.  Closed loop means less emissions. 

Cold start/warm up is Open Loop until O2 sensors are up to temp and the ECM has gone through it's start up tables if the engine is already warm.

Once in Closed loop the ECM chases the AFR Target (from the Fuel map) based on the output provided by the O2.  If O2 voltage is lower or higher than 450mv the ECM shortens or lengthens the injector pulse width and monitors the O2 output until it reaches target. 

[07heri]

The Narrow Band sensor Outputs between .02 and .08 V. 

Now I'm really confused    Do you have a reference to those voltages?

[RideFree]

NB sensors are junk, don't waste your time with them. Any deviation from 14.6 AFR like below 14.4 AFR for example and the signal falls faster than my pants in Nevada. The relatively expensive and I think the correct way to tune ECU motorcycles are with WB sensors and an auto tuner whether real time auto tune or off line auto tune. It is head over heels better than anything the NB sensors give you. Plus you can real time view your AFRs. We are getting screwed not having WB sensors and WB closed loop. There I said it again.

[hrdtail78]

They are in the chart Zoot's link takes you too.  Integrators are also helpful when looking at rich/lean and health of a tune.  O2 feedback in TTS data master helps to know what condition the ECM is in.  Rich mode or lean mode.  In the upper right hand corner.

HTH

[hrdtail78]

NB sensors are junk, don't waste your time with them. Any deviation from 14.6 AFR like below 14.4 AFR for example and the signal falls faster than my pants in Nevada. The relatively expensive and I think the correct way to tune ECU motorcycles are with WB sensors and an auto tuner whether real time auto tune or off line auto tune. It is head over heels better than anything the NB sensors give you. Plus you can real time view your AFRs. We are getting screwed not having WB sensors and WB closed loop. There I said it again.

...and you came to this conclusion how?  What aftermarket tuners on the market use wide bands?

[rageglide]

The Narrow Band sensor Outputs between .02 and .08 V. 

Now I'm really confused    Do you have a reference to those voltages?

Zoots link is pretty good, although the flow charts are a little goofy to follow (at least to me).   There's also a link to wikipedia listed on that page.   This is the page.  http://en.wikipedia.org/wiki/Oxygen_sensor  Look at "Operation of the Probe" section. 

[joe_lyons]

The narrowbands are all a 0-1V. You will see higher voltages with what's called a bias voltage which can vary between cals.  The bias voltage is applied through the ground side of the sensor for a different resolution area.  I have no problems with narrowband sensors.

[hrdtail78]

It is 0-1 volt but a rule of thumb is .8. As you can see by the chart. It slides pretty quick above .8.  I am sure there is a limit on the leaner side as well but who is trying to run the bike leaner than stoich?

[RideFree]

...and you came to this conclusion how?  What aftermarket tuners on the market use wide bands?

Let's say Harley as well as other manufacturers contract with ThunderMax or DynoJet (Power Commander) to name a couple to provide WB closed-loop Auto Tune right off the showroom floor. Hence conclusion and the What. The EPA won't allow that. Hence the screwing. NB's only allow for tuning in a very narrow range that is really of no use, 14.7 to 14.4 AFR is well not even worth the trouble. You need WB's.

A question to ask is why don't dyno's use NB's? Because they are junk to tune with at anything other than ~14.7 AFR.

[hrdtail78]

 

[joe_lyons]

What do you do for a living Ridefree? I had the auto tune pro setup on my bike along with the nb sensors and while the pro kit is nice to have it is not a necessity.  All of it depends on sensor location and how good the read is with any of the sensors.

[wolf_59]

Correct where my assumptions are wrong:

1)  The sensor can read from 1 volt to 5 volts
     as was stated 0-1

2)  It will read way high during warm up.  How much higher?
     around 1500 and as they warm up they start dropping

3)  Once both fire off they should fluctuate higher and lower around .450 (CLB).  How much swing would be considered normal?
     as long as they are fluctuating they're working.  You won't be normal for long if you try to figure this out 

4)  This fluctuation should remain in idle, steady state, or anytime in CL. Yes

5)  Accel or decel should go rich with higher readings, and stay higher until CL kicks back in   Yes

6)  IDLE:  Voltages should fluctuate in CL.  OL voltages will remain steady at whatever the sensor
is reading.  I wasn't sure if the sensor still reads and responds, and the ECM just doesn't acknowledge it.  Or if the sensor was totally offline. Sensor is still in the exhaust stream so still reads and sends info ECM just ignores the information in OL

7)  If VE's are way off to the high side the sensor may never have a chance to toggle below .450.  How
does the ECM handle this?  Does it keep trying to reduce fuel every polling cycle?  What happens if the ECM can't get below .450?
Way to rich sensor will not work, If sensor is not coming on line try dropping VE's in that area by 20 and try again

[RideFree]

What do you do for a living Ridefree? I had the auto tune pro setup on my bike along with the nb sensors and while the pro kit is nice to have it is not a necessity.  All of it depends on sensor location and how good the read is with any of the sensors.

"I'm just a small town cop, mostly I give out parking tickets." ;-p

For real? Now: computer programmer, past: Nuclear Reactor Operator, NRC licensed for many decades, too many graveyards. 

You can tune within the narrowband range which is way too narrow for me. Any time you change the Volumetric Efficiency (VE) tables without proper feedback you are taking a risk. Plus the ECU will kick itself out of closed loop when it sees the sensor signals getting close to being out of range around 14.34 AFR.

Sensors have grown up over the years. They are pretty fool proof now if you follow the manufacturers installation instructions and test them in air before putting them in, they have an air test procedure. O2 sensors nowadays are pretty problem free and work as designed.

I'm a proponent that every motorcycle should have and be using WB sensors closed or open loop tuned.

[joe_lyons]

So in that list I did not see dyno tuner / engine builder / ECM programmer.  Since you have not learned how to tune a bike with narrow band sensors I guess you don't realize there potential.  Ass revolution performance how the wideband set up worked for them.

[RideFree]

It is 0-1 volt but a rule of thumb is .8. As you can see by the chart. It slides pretty quick above .8.  I am sure there is a limit on the leaner side as well but who is trying to run the bike leaner than stoich?

Superimpose the AFR scale for lambda. 11.712, 12.444, 13.176, 13.908, 14.64, 15.372, 16.104, 16.836, 17.568 and with the controllable or useful lower range being 14.3472 (.98) before the ECU kicks itself out of closed loop, 14.4 (.9836) is the lowest AFR setting that will still maintain closed loop. Actually anything >700mV and <200mV is falling off a cliff and not really useable IMO.

[RideFree]

So in that list I did not see dyno tuner / engine builder / ECM programmer.  Since you have not learned how to tune a bike with narrow band sensors I guess you don't realize there potential.  Ass revolution performance how the wideband set up worked for them.

I cannot believe you are dumping on WB's for NB's. That's just crazy. Why would you want to tune where its hot and less performance in a tiny range. Tuning with NB's outside the NB's range is tuning blind. Get the AFR down where it's cooler and more performance with the proper feedback. Use WB's.

I know, my mistake, you have to be in the "dyno tuner / engine builder / ECM programmer" industry to post experiences and ideas here. My bad.

[joe_lyons]

No no anyone post.  I use wide bands all the time on my dyno I also use narrow bands. For everyone that out there you can't just say the only way to tune a bike is to throw wide band at it.  Many many people have to be there by like it narrow band and decent results. 

[RideFree]

No no anyone post.  I use wide bands all the time on my dyno I also use narrow bands. For everyone that out there you can't just say the only way to tune a bike is to throw wide band at it.  Many many people have to be there by like it narrow band and decent results.

Never said they were the only way. Said I won't use them and why and what I thought of them based on my experience using both NB basic auto tune and WB pro auto tune. Would you run a dyno without WB sensors, then why should I?

[hrdtail78]

I disagree with the ranges you are stating for NB and fuel requirements our Harley's need.  I have heard the cooling myth before, but nobody can explain the latent heat in fuel and how more fuel is actually added when someone targets 13.8 instead of 14.3.  That is .5   Is the latent heat of that much more fuel doing anything?

Sensors have grown up over the years. They are pretty fool proof now if you follow the manufacturers installation instructions and test them in air before putting them in, they have an air test procedure. O2 sensors nowadays are pretty problem free and work as designed.

And what aftermarket system uses "wide band" sensor that follow the manufactures installation instructions?  The sensor manufacture?  Not the tuner's.  I don't want to get too far into that but it needs to be mentioned.

What are the sampling rates of the "WB" sensors you are using?  What are the NB sensor sampling rates?  At what crank position does "WB" sensors poll?  What crank position does the NB poll data?

This is stuff I would look into before claiming something is junk and has no place while tuning an engine.  I use both narrow bands and broad bands while tuning.  They both have their places in the HD tuning world.



Congrates on the new dyno, Joe.

[lonewolf]

And what aftermarket system uses "wide band" sensor that follow the manufactures installation instructions?  The sensor manufacture?  Not the tuner's.  I don't want to get too far into that but it needs to be mentioned.

What are the sampling rates of the "WB" sensors you are using?  What are the NB sensor sampling rates?  At what crank position does "WB" sensors poll?  What crank position does the NB poll data?

This is stuff I would look into before claiming something is junk and has no place while tuning an engine.  I use both narrow bands and broad bands while tuning.  They both have their places in the HD tuning world.

I agree.

[07heri]

Is 0 to 1v the operating range?  I'm seeing voltages way way above, like 3.xx in a log.  If they only read up to 1 volt why would a log show higher.  I figure it's showing rich but they must be able to read higher than 1v if the log is showing me numbers way above 1v.  In theory 0 to 1 sounds right, but it looks like they can read higher than 1v.  No?

Would be nice to see a log of a good tune and see how the voltages fluctuate.  Then compare to a crappy tune.  Anyone have some logs for learning purposes?

[joe_lyons]

Bias voltage put through the ground side

[07heri]

Bias voltage put through the ground side

I'm a little slow.  Can you show some math to explain this?

[joe_lyons]

The signal side of the 02 sensor has two wires. One is for (ground) the other is (signal) the ecm will put what's called a bias voltage through the (ground)side to change the range.

[RideFree]

I disagree with the ranges you are stating for NB and fuel requirements our Harley's need.  I have heard the cooling myth before, but nobody can explain the latent heat in fuel and how more fuel is actually added when someone targets 13.8 instead of 14.3.  That is .5   Is the latent heat of that much more fuel doing anything?

Sensors have grown up over the years. They are pretty fool proof now if you follow the manufacturers installation instructions and test them in air before putting them in, they have an air test procedure. O2 sensors nowadays are pretty problem free and work as designed.

And what aftermarket system uses "wide band" sensor that follow the manufactures installation instructions?  The sensor manufacture?  Not the tuner's.  I don't want to get too far into that but it needs to be mentioned.

What are the sampling rates of the "WB" sensors you are using?  What are the NB sensor sampling rates?  At what crank position does "WB" sensors poll?  What crank position does the NB poll data?

This is stuff I would look into before claiming something is junk and has no place while tuning an engine.  I use both narrow bands and broad bands while tuning.  They both have their places in the HD tuning world.

Using O2 sensors properly is a trifecta of the O2 sensor manufacturers installation and operation instructions. First the exhaust manufacturer installs the bungs at the appropriate distance in the pipe from the exhaust valve and at the proper angle. Then the tuner manufacturer creates a product with circuits that properly use the signals generated by the sensors. Then the user or installer follows their part of the O2 sensor instructions which are probably now rendered in the tuners instructions to air test the sensors and then not get any antiseize on the sensor and tighten appropriately. If all that is done properly per manufacturers specs then you have properly working O2 sensors for a long time until ridden into a lake of course.

Two after market tuners that use WB sensors as stated previously are TMax, Power Commander, and PV with AT Pro. You use their products with an exhaust system that has 18mm bungs installed properly and things will work a whole lot better than NB tuning. I've done both and I'm not talking about set it and forget it dynos. I'm talking about tune it yourself then add a different cam, a different air cleaner and tune it yourself again and real-time monitor both cylinder AFR's running at ~13.8 AFR which is below the NB accuracy range. Use WB!

Relative to WB tuning, NB tuning is junk. We only do it because we are forced to.

You can look up that information and let us know here what you find.

[hrdtail78]

"Using O2 sensors properly is a trifecta of the O2 sensor manufacturers installation and operation instructions. First the exhaust manufacturer installs the bungs at the appropriate distance in the pipe from the exhaust valve and at the proper angle. Then the tuner manufacturer creates a product with circuits that properly use the signals generated by the sensors."

Do you get a free unicorn also?

Both sensors have their problem, and there place.  I don't only want to target 13.8 or richer.  Lower kpa areas I target AFR ratios inside the NB's range.  The frequency of the sample at a known crank position puts ECM read NBs, VE mapping the best way it can be done.  They are not junk.

[rageglide]

Is 0 to 1v the operating range?  I'm seeing voltages way way above, like 3.xx in a log.  If they only read up to 1 volt why would a log show higher.  I figure it's showing rich but they must be able to read higher than 1v if the log is showing me numbers way above 1v.  In theory 0 to 1 sounds right, but it looks like they can read higher than 1v.  No?

Would be nice to see a log of a good tune and see how the voltages fluctuate.  Then compare to a crappy tune.  Anyone have some logs for learning purposes?

The values you see above 1V are the voltage required to keep the O2 in spec.  Drop exhaust temp and the heat circuit needs to kick it up to insure the O2 is running at the most accurate temp.  Raise temps (lean running) the heater circuit voltage will drop.

[joe_lyons]

The ecm uses the bias voltage as a test for how warm the sensor is.  If you notice that when you first start up that your sensor voltage is 5 volts, that is the ecm using its thermometer to see how hot the sensor is and as it warms up either through a heater circuit and/or without(exhaust temp alone) the voltage drops .  Then to keep an eye on the temp it uses the bias voltage (which varies between cals).  Bias voltage and heater circuit are two separate circuits and only work side by side. 
Here is a cool video that does a little bit of explaining
https://www.youtube.com/watch?v=v8XrM-7BuOg

[Karl H.]

Great Video! 

[rageglide]

  

[scott45acp]

What does the O2 sensor actually measure?  If it was oxygen then it could not read afr below 14.6 because the 02 would be used up.  If it was hydrocarbon then it could not read above 14.6 because there would be no unburned fuel.

[rageglide]

What does the O2 sensor actually measure?  If it was oxygen then it could not read afr below 14.6 because the 02 would be used up.  If it was hydrocarbon then it could not read above 14.6 because there would be no unburned fuel.

Wikipedia has lots of good info about how an O2 works.  They don't measure AFR.  This is a good explanation from Wikipedia, better than I could say explain it.

"The sensor does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in air. Rich mixture causes an oxygen demand. This demand causes a voltage to build up, due to transportation of oxygen ions through the sensor layer. Lean mixture causes low voltage, since there is an oxygen excess."

http://en.wikipedia.org/wiki/Oxygen_sensor

[07heri]

Is 0 to 1v the operating range?  I'm seeing voltages way way above, like 3.xx in a log.  If they only read up to 1 volt why would a log show higher.  I figure it's showing rich but they must be able to read higher than 1v if the log is showing me numbers way above 1v.  In theory 0 to 1 sounds right, but it looks like they can read higher than 1v.  No?

Would be nice to see a log of a good tune and see how the voltages fluctuate.  Then compare to a crappy tune.  Anyone have some logs for learning purposes?

The values you see above 1V are the voltage required to keep the O2 in spec.  Drop exhaust temp and the heat circuit needs to kick it up to insure the O2 is running at the most accurate temp.  Raise temps (lean running) the heater circuit voltage will drop.

I dont have a heater circuit on an 07.  Just 2 wires.

[joe_lyons]

But it still uses the bias voltage as a check on the temp of the sensor.  Not that it can do anything about it.

[07heri]

The ecm uses the bias voltage as a test for how warm the sensor is.  If you notice that when you first start up that your sensor voltage is 5 volts, that is the ecm using its thermometer to see how hot the sensor is and as it warms up either through a heater circuit and/or without(exhaust temp alone) the voltage drops .  Then to keep an eye on the temp it uses the bias voltage (which varies between cals).  Bias voltage and heater circuit are two separate circuits and only work side by side. 
Here is a cool video that does a little bit of explaining
https://www.youtube.com/watch?v=v8XrM-7BuOg

Good video Joe.  I have a way high voltage reading on the rear.  I also have a high VE number, 108, at idle.  Even though I dont have a heater circuit if I'm way rich it wont allow the 02 to heat up and thus give me a high voltage reading...similar to a bad heater circuit causing a high voltage?

[joe_lyons]

Bingo sir.  Thats exactly what the guy said in the video.  You could have a junk sensor.  Does it become active at any point in time? 

[Tsani]

But it still uses the bias voltage as a check on the temp of the sensor.  Not that it can do anything about it.

So, it is normal to have delays greater than 40 to 60 seconds for the sensor to reach the switching threshold in a sensor with out heaters?

[joe_lyons]

That seems a little slow.  If you rev it up or go for a ride do they come on quicker?

[Tsani]

That seems a little slow.  If you rev it up or go for a ride do they come on quicker?

I would need to go over the logs but I believe so. Stock softail headpipe with CS slip ons. Takes the front about 30 seconds for the front O2 to start dropping off of 5100 and the rear follows about 10 seconds later. About a minute or so later you see them fluctuating "normally".  Heating the engine up faster does change the time some but not by much. I think its a combination fuel cooling issue as well as placement. The time does change with restarts like after a regassing for instance but the engine temps can drop fairly well too so I assume everything is sinking heat. These were new sensors but I know that doesn't mean they can't be faulty to some degree and I will be trying another set. Once everything is warmed up, bike runs fine and as it warms up seems to do well. And at that point it doesn't matter because it is in open loop in that area. But sometimes I wonder if it is not due to ECM coding or is what we see in the data recording actually data from the sensor at the moment it is occurring? I know that may sound like a strange question but is it possible that the ECM doesn't poll the sensors or output O2 data to the data plug until a certain amount of time has passed? I could see programing doing that and was wondering.

Not looking to start a mess about WB v.s. NB or what device is better. Just trying to understand a few things about the sensors and also the ECM because who knows what they do with the coding. But I do know from working PLC's and such that that is a possible scenario.

[Jamie Long]

That seems a little slow.  If you rev it up or go for a ride do they come on quicker?

I would need to go over the logs but I believe so. Stock softail headpipe with CS slip ons. Takes the front about 30 seconds for the front O2 to start dropping off of 5100 and the rear follows about 10 seconds later. About a minute or so later you see them fluctuating "normally".  Heating the engine up faster does change the time some but not by much. I think its a combination fuel cooling issue as well as placement. The time does change with restarts like after a regassing for instance but the engine temps can drop fairly well too so I assume everything is sinking heat. These were new sensors but I know that doesn't mean they can't be faulty to some degree and I will be trying another set. Once everything is warmed up, bike runs fine and as it warms up seems to do well. And at that point it doesn't matter because it is in open loop in that area. But sometimes I wonder if it is not due to ECM coding or is what we see in the data recording actually data from the sensor at the moment it is occurring? I know that may sound like a strange question but is it possible that the ECM doesn't poll the sensors or output O2 data to the data plug until a certain amount of time has passed? I could see programing doing that and was wondering.

Not looking to start a mess about WB v.s. NB or what device is better. Just trying to understand a few things about the sensors and also the ECM because who knows what they do with the coding. But I do know from working PLC's and such that that is a possible scenario.

The operation you are noting is normal for models with non-heated O2 sensors. When the sensor relies on EGT to get up to temp the amount of time it takes closed loop to come online is relative. As far as closed loop itself there are several weighted factors in the code that that affect when the integrator starts rolling, in this regard most importantly run time vs engine temp.   

[Jamie Long]

Here is a chart which references O2 voltage vs. AFR (assuming 14.7 stoich). Note the non linear output of the sensor, specifically what happens to voltage below 14.2 and above 15.0

[Tsani]

That seems a little slow.  If you rev it up or go for a ride do they come on quicker?

I would need to go over the logs but I believe so. Stock softail headpipe with CS slip ons. Takes the front about 30 seconds for the front O2 to start dropping off of 5100 and the rear follows about 10 seconds later. About a minute or so later you see them fluctuating "normally".  Heating the engine up faster does change the time some but not by much. I think its a combination fuel cooling issue as well as placement. The time does change with restarts like after a regassing for instance but the engine temps can drop fairly well too so I assume everything is sinking heat. These were new sensors but I know that doesn't mean they can't be faulty to some degree and I will be trying another set. Once everything is warmed up, bike runs fine and as it warms up seems to do well. And at that point it doesn't matter because it is in open loop in that area. But sometimes I wonder if it is not due to ECM coding or is what we see in the data recording actually data from the sensor at the moment it is occurring? I know that may sound like a strange question but is it possible that the ECM doesn't poll the sensors or output O2 data to the data plug until a certain amount of time has passed? I could see programing doing that and was wondering.

Not looking to start a mess about WB v.s. NB or what device is better. Just trying to understand a few things about the sensors and also the ECM because who knows what they do with the coding. But I do know from working PLC's and such that that is a possible scenario.

The operation you are noting is normal for models with non-heated O2 sensors. When the sensor relies on EGT to get up to temp the amount of time it takes closed loop to come online is relative. As far as closed loop itself there are several weighted factors in the code that that affect when the integrator starts rolling, in this regard most importantly run time vs engine temp.

Thanks Jamie. Makes sense.

[07heri]

Bingo sir.  Thats exactly what the guy said in the video.  You could have a junk sensor.  Does it become active at any point in time?

The sensor only has 3k or so on it, but could still be junk.  I'm betting more on an exhaust leak (messed up my VE's on last couple auto tune runs) and waiting for the gaskets from the dealer.  Once I get it sealed back up I was going to manually drop the high VE at idle down a bunch and see if the sensor responds accordingly.  The last auto tune run ended up at 108 VE at idle on rear and it stinks rich.  If it's a rich condition I should be able to see it start lowering voltages as I drop the VE's.  Assuming the sensor is good and the leaks are tight.  Do you agree? 

[joe_lyons]

What headpipe do you have?  If stock then the rear will always have issues because of the goofy y section that pulls in air

[rigidthumper]

Last time I saw unusually high VEs @ idle in one cylinder and low in the other cylinder  the 02 sensors were swapped. 

[07heri]

What headpipe do you have?  If stock then the rear will always have issues because of the goofy y section that pulls in air

Stock Softail headpipes.  The rear has always been a problem with leaks at the crossover.  I think that may be part of the high VE's, which is giving me high 02 voltages.  Once I get it sealed up I will give it another shot and see what the 02 does. 

[lonewolf]

Wouldn't the o2 voltages have to be low to cause the high ve's?

[joe_lyons]

Use some copper exhaust sealant at the crossover and at the exhaust port, that stuff does wonders.

[Karl H.]

Wouldn't the o2 voltages have to be low to cause the high ve's?

[joe_lyons]

It would have to go into closed loop for it to do anything first.  A simple test just for giggles would be to swap sensors and just double check that.  Some bikes and pipes just don't do a very good job at all of getting a good read at idle with the O2 sensors.  For this reason I put most bikes in open loop at idle.  If you rev it up and the sensor comes back to life and then just cools back down when you go back to idle then the signal that you are getting from it I would say is unreliable in that area.  In the basic tune settings you can set the min/max of areas that are altered.

[rbabos]

Wouldn't the o2 voltages have to be low to cause the high ve's?

That's been my experience also. First noticed with an MT8 cal with ci too high in the constants. 2400 O2 volts and it was driving the ve's down. Once leaned out they started switching and ve's went up.
Ron

[hrdtail78]

But it still uses the bias voltage as a check on the temp of the sensor.  Not that it can do anything about it.

So, it is normal to have delays greater than 40 to 60 seconds for the sensor to reach the switching threshold in a sensor with out heaters?

I wouldn't say that is out of the norm.  Set warm up enrichment table to 0 and time from a cold start.  That is just one thing that can delay sensors coming on line.

[07heri]

Wouldn't the o2 voltages have to be low to cause the high ve's?

What are you calling low?   

[07heri]

Bingo sir.  Thats exactly what the guy said in the video.  You could have a junk sensor.  Does it become active at any point in time?

100% not a junk sensor.  I sealed up the exhaust with the -10 seals instead of the catalogs -03 seals, at the interconnect pipe.  Sliced 4 cuts into the pipe that slides over the interconnect seal and put homemade clamps on the pipe.  Finally a good seal.  Manually dropped the rear VE's to equal the front plus 10% to experiment.  Fired up the bike and watched 02 voltage on PV.  Started at 5.1 volts and within 60 seconds or so (43 degrees F in the garage) started seeing the voltage come down.  As the sensors heated up the voltage came right down to where they should be.  Both sensors are reading up and down super fast, just like the video.  The rear never moved like they are now.  Both front and rear from like .18 to .9 up and down fast.    Even at idle the voltage changes are super fast.  I had the bias set at .450 and it was pretty close to the same increase and decrease in voltage.  All this grief over a stinking exhaust leak. 

Now that I finally have the 02 issue worked out I'm curious to see how it tunes up.  That exhaust leak raised hell with me for over a year.  After going through all this and finally getting it straightened out the first thing I would tell a beginner DIY'er is to look at the 02's before even beginning to tune.  If those 02's aren't clearly working right I can see someone chasing their tale forever with these DIY tuning gadgets.