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Author Topic: wideband O2 sensor q's  (Read 25777 times)
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NathanStewart
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« Reply #15 on: April 21, 2015, 02:14:00 PM »

The EFI sytem I am working on for racing will be mapped for the motor on the dyno using the oxygen sensors and a Bazazz self tuning module in closed loop mode.  Then, the sensors will be removed before the leaded gas trashes them.  The system will be switched to open loop mode for racing.  I do not know if this will work, but it is what I am doing based on some advice by locals.       

"Self tuning modules" are what keep tuners in business.  Or in other words, they kinda suck... or at least that's what a lot of people tell me when they ask me to tune for them after their self tuning thingy didn't do a very good job of self tuning.  You're probably better off tuning it yourself.  No reason to take the sensors out even though you'll be running open loop.  Might as well still monitor O2.  FWIW I NEVER run closed loop on a racing application.     

There are many reasons why these systems do not work properly. The biggest one is none of the aftermarket electronics follow what Bosch states in there tech sheets must be done. As for current draw a single channel system will surge to 6 + amps on start-up then drop to about a steady 3 - 3.5 amp draw when running. The units MUST be calibrated each time you go to use them and if your plan is to change altitude greater than 1000 ft you will need to shut it down and once cool, fire it back-up and recalibrate to get somewhat accurate readings.

Hmm I've never heard of any of the hundreds of thousands (millions?) of OEM cars that use Bosch wideband sensors having to do that. 
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El Mirage 200 MPH Club Member
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« Reply #16 on: April 21, 2015, 09:07:41 PM »

Thanks for the advice, Nathan.  The Triumph boxes can be remapped using TuneECU and I have done it.  The Yamaha that is a subject of this thread might be able to run a Keihin ECU unit for a Triumph twin.  That will enable Tune ECU to be used to map it.  Both are parallel twins.

How do you prevent the oxygen sensors from being destroyed by the lead in the gas?   
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TheBaron
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« Reply #17 on: April 21, 2015, 10:03:11 PM »

You Don't..

the lead knocks them out of calibration first , and then they die.

According to some info I've read, they can last up to about 50 hours in some cases,,,less in others. However, that can be a lot of runs for a pure racing vehicle, and even when out of calibration they still will show a change in the fuel mixture in the correct direction of richer or leaner.

I've considered flushing the race gas and running the vehicle on unleaded for  15 minute to see if that would extend there life, but it is just too much trouble for unknown results.

Robert
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NathanStewart
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« Reply #18 on: April 22, 2015, 03:05:02 PM »

You Don't..

Right, you don't.  They typically don't up and die instantly.  I've seen lots of dry lakes race vehicles go a whole season using the same sensor while running leaded gas.  You'll know when they go and when they do, just replace it.
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wobblywalrus
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« Reply #19 on: April 24, 2015, 09:48:08 PM »

The fellow who does the mapping for me on his dyno prefers to use his oxygen sensor.  The Triumph will be set up without any oxygen sensors.  That is commonly done around here.

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Saltfever
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« Reply #20 on: April 27, 2015, 01:28:47 AM »

You can heat a contaminated sensor with a common propane torch to try and give it some extra life. Don't expect to get it right the first time, you might loose one. I think Bosch specs the max body temp to not exceeded 950F max. Yeah, I know a bad turbo installation will far exceed that, I'm just indicating that there is an actual "never exceed" spec for body temp. Under excess heat conditions there are a few tricks like a tube extender or a copper heat sink that can be used. But I digress . . .  Using a propane torch you don't want the nertz cell to glow dull red. It has to get hot enough to burn off the lead but no so hot to fry the internals. I have saved (and lost) a few that way. As already indicated, lead contamination slows down response time. On a close-loop street motor, response time is important. But running a slow sensor on an open-loop, WOT, 2 minute, full pull, is not such a big deal for Bonneville. You will be running data acquisition and even a slow sensor will give you a reading. Just calibrate for reassurance.
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wobblywalrus
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« Reply #21 on: June 21, 2015, 01:19:20 AM »

This topic was discussed with a fellow in Britain that knows a lot more about EFI than me.  He said the role is simple of the oxygen sensor in the typical original equipment manufacturer EFI system.  He said it uses occasional measurements to adjust the trim of the fueling curves.  In the case of the Keihin EFI system on my Triumph, the sensor readings for open throttle operation are taken after 10 minutes or so of running.  This assures the curves are trimmed for a fully warmed up engine.  He said the closed loop feature will not do me any good.  The run is over before the sensor takes a reading unless I change the sampling frequency, he said.  In summary, he told me to pay particular attention to when the sensor readings are taken for closed loop operation.  He mentioned that the readings need to be often enough to be useful.

He also mentioned that almost all race motors have some reversion and it is important that the sensor does not take a measurement during this condition.  It would make an adjustment to the mixture that would not be good for running at rpm outside of the reversion zone. 
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manta22
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« Reply #22 on: June 21, 2015, 02:30:50 PM »

This topic was discussed with a fellow in Britain that knows a lot more about EFI than me.  He said the role is simple of the oxygen sensor in the typical original equipment manufacturer EFI system.  He said it uses occasional measurements to adjust the trim of the fueling curves.  In the case of the Keihin EFI system on my Triumph, the sensor readings for open throttle operation are taken after 10 minutes or so of running.  This assures the curves are trimmed for a fully warmed up engine.  He said the closed loop feature will not do me any good.  The run is over before the sensor takes a reading unless I change the sampling frequency, he said.  In summary, he told me to pay particular attention to when the sensor readings are taken for closed loop operation.  He mentioned that the readings need to be often enough to be useful.

He also mentioned that almost all race motors have some reversion and it is important that the sensor does not take a measurement during this condition.  It would make an adjustment to the mixture that would not be good for running at rpm outside of the reversion zone. 

WW;

If that last paragraph is true there would be only one RPM where the reading would be correct. To solve that problem, the O2 sensor reading could be sync'ed with a delay after TDC or after the ignition fires the plug. I've never tried this though.

Regards, Neil Tucson, AZ
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Regards, Neil  Tucson, AZ
Stainless1
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« Reply #23 on: June 21, 2015, 07:43:42 PM »

The reversion zone in a pipe is close to the end... that is why you don't put the sensor within 16 inches from the end of the pipe... However, at high RPM and WOT I doubt you will see a reversion area in the pipe, very little possibility of sucking O2 in and screwing up the readings.
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Stainless
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MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.
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« Reply #24 on: June 22, 2015, 10:35:24 PM »

Thanks, Stainless.  That might be one of our problems.  The little stinger with the sensor we use for tuning does not go far enough up the muffler.  That probably is not a problem for standard OEM engines and it may lead to false readings on my race motor with the bumpy cams.
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Steve Cole
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« Reply #25 on: September 13, 2015, 04:09:38 PM »

One needs to understand a few basic things about a Bosch sensor and it is all clearly spelled out in the Bosch documents. The OEM's know and follow the rules, the aftermarket does NOT. The sensor is a free oxygen sensor it does NOT measure fuel mixture. The sensor has to have all the necessary measurements taken to give a correct reading, again this is all covered in the Bosch specifications! So if you doubt what I say, just go get a copy of the specification and read them, then go look at the aftermarket systems and see all the missing pieces they do not do.

The biggest one is the sensor output has to be corrected for altitude, exhaust pressure and temperature at the time the reading is taken. I have yet to see ANY aftermarket system that does this and that's is the issue. The OEM's do not use the sensor the same way the aftermarket does, let alone the way a racer does. We ran a test years ago with one pipe, test gas and about 10 different aftermarket systems tied into the pipe. Funny thing not one of them provided a correct reading of the test gas and none of them read the same. So which one do you want to use is up to you but do not for a moment thing the numbers your seeing are correct!

They provide an indication of richer or leaner but the absolute numbers are incorrect and as you travel up and down in altitude it gets worse. It's a tool like any other tool but they have there limits and as long as you know them you should be fine. If someone tells you there is a magic number they had Dodge well better have a few of those magic numbers for all altitudes!
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Saltfever
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« Reply #26 on: September 13, 2015, 06:24:09 PM »


The biggest one is the sensor output has to be corrected for altitude, exhaust pressure and temperature at the time the reading is taken. I have yet to see ANY aftermarket system that does this and that's is the issue.
Not true. Innovate has always required calibration for altitude and explains the calibration process in detail.  http://www.innovatemotorsports.com/resources/whycalibrate.php

The Auto Tune calibrates for altitude. Read the last paragraph.
http://www.powercommander.com/downloads/Support-Released/AutoTune/Manuals/AT-300.01.pdf

We ran a test years ago with one pipe, test gas and about 10 different aftermarket systems tied into the pipe. Funny thing not one of them provided a correct reading of the test gas and none of them read the same. So which one do you want to use is up to you but do not for a moment thing the numbers your seeing are correct!

I remember a magazine test like that a few years ago. Sensors were arranged completely around the pipe, all at the same distance. IIRC, one sensor in the test measured correctly. Is that the test you are referring to?


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Steve Cole
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« Reply #27 on: September 14, 2015, 03:01:32 PM »

What I can tell you from real world testing, the DynoJet stuff doesn't work well at all. Measuring a fixed test gas (13.23)at sea level up to 8000' showed different readings at all test locations and the range was over 1.5 AFR! So if they claim it adjust for altitude it doesn't work or work correctly. They would be one of the last ones I would ever use.

The Innovate unit is one of the better ones but they tend to burn up the Bosch O2 sensors in short order too. Last I looked you had to perform the altitude adjustment manually on them, which means you are stuck running at only one altitude, then stopping and going through a recalibration procedure each time you have a change in altitude. Not a big deal on a dyno but not so good for an over the road vehicle. Also, you didn't bring up the fact of the corrections necessary for exhaust pressure and temperature. In my book you need to follow what the manufacture (Bosch) tells you to do IF you want accurate and repeatable results! The simple fact is that none of the units I have seen or tested will do that and that limits there ability to work well. If you want a good one here is one of the best aftermarket units out today, but they are expensive. It is also the one from the article that test accurately during there testing at a fixed altitude, temperature and pressure.

http://www.ecm-co.com/product.asp?5220

Like anything else you got to pay if you want to play! These are the units the OEM's (Ford, GM, Chrysler, ect.) use too! Yes, I own them too and understand what they will and willnot do.
« Last Edit: September 14, 2015, 03:06:25 PM by Steve Cole » Logged
Steve Cole
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« Reply #28 on: September 14, 2015, 07:53:33 PM »

I've attached a picture of what the influence of exhaust pressure and altitude are on a Bosch sensor per the Bosch specifications. This still leaves out the other corrections and this is only for a mixture of 13.23 AFR. Since the corrections are not straight forward and vary as the mixture level does I though this might help some of you understand it a little better. Remember this is straight out of the Bosch specification data and why it is so important to understand. I cannot understand why the aftermarket systems would chose to ignore it.


* 13.23 AFR Spread.JPG (241.78 KB, 1284x1024 - viewed 331 times.)
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Saltfever
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« Reply #29 on: September 15, 2015, 02:24:57 AM »

I come from an environment where bad information is far worse than no information. Having no information forces the human mind to adapt or look for solutions. Bad information will lead you unknowingly to your death.

The Innovate sensor will not report AFR if conditions fall outside the Bosch calibration resistor rather than report erroneous numbers.  I would rather have no AFR than unknowingly follow a bad number. Yes, Innovate wants you to remove the sensor from the exhaust pipe. It is so sensitive it can detect residual gasses left over from many hours before. The only scientifically correct way to calibrate for fresh air is to actually calibrate in fresh air! Removing the sensor is the only way to do that. You indicate that is a bad thing. Big deal, calibrating 2 sensors is far easier than pulling 8 plugs 3 times a weekend. Calibrating for altitude is fairly irrelevant for me. When I arrive at a race track I calibrate. Usually, it is racing for the weekend and then I go home. Maybe a month or two later Ill arrive at a different venue and calibrate. You are implying a trivial activity is a nuisance. We are racers . . . we do tedious things because we love to do it.

Please read this and comment.
http://www.innovatemotorsports.com/resources/whycalibrate.php

Thank you for the Bosch chart.


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