Landracing Forum
Tech Information => EFI Questions => Topic started by: Vishnuatepork on March 05, 2015, 09:44:59 PM
-
Hello Guys! and Gals!, if theres any Gals here....
Motorcycle; Yamaha MT-01 (same engine as Yamaha Warrior)
with; power commander V and AT-300 (Auto tune)
A mate and I are trying to figure out just how effective the tuning is on the Dyno Jet Power Commander on my bike.
The Auto Tune, kind of tunes it self, using the O2 sensor....
but as we are slowly watching and learning, the O2 sensor(s) dont always seem to be 100%. And if you continually accept the suggested trim values, it tends to a wee bit lean. We think this is because of an old/miscalibrated/worn O2 sensor.
Bosch even put out a service bulletin stating that O2 sensors may have upto a 5% skew.
Bosch Y 258 K01 005-000e technical document.
So what Im trying to figure out, is,
1) Is there a better brand of wideband sensor - -what does everyone here use?
2) How do you measure your afr?
3) how much trust do you put in your O2 sensors accuracy?
Cheers
Alan
-
1) Is there a better brand of wideband sensor - -what does everyone here use?
2) How do you measure your afr?
3) how much trust do you put in your O2 sensors accuracy?
1) I use the same sensor, the Bosch LSU4.2, as well as the Bosch LSU4.9. Both read the same values for me but the 4.9 lights off a wee bit faster than the 4.2. That doesn't matter for me since they both light off far quicker than I need them. I have also tested the NGK L1H1 and the NGK LHA. They have a better reputation for longevity in leaded fuel but I have not experienced that in my case since I change the sensors out every couple of years, which is nothing on the longevity scale. The Bosch sensors seem to respond much faster to events than the NGKs do. 4.9 < 4.2 < LHA < L1H1.
2) I have 7 of them on the roadster, one in each cylinder and a single one in the downpipe after the turbo.
3) Trust, but verify. We pull the plugs after every pass and tune accordingly. The sensors are not a magic bullet. They measure oxygen in the exhaust and then make a logical jump to the AFR that would have resulted in that O2 concentration. But an exhaust leak or even a misfire will screw the reading up since both events will allow extra O2 to be present in the exhaust, and the O2 sensor thinks that means you were running leaner than you were.
Just my $0.02, YMMV
-
1) Is there a better brand of wideband sensor - -what does everyone here use?
2) How do you measure your afr?
3) how much trust do you put in your O2 sensors accuracy?
1) I use the same sensor, the Bosch LSU4.2, as well as the Bosch LSU4.9. Both read the same values for me but the 4.9 lights off a wee bit faster than the 4.2. That doesn't matter for me since they both light off far quicker than I need them. I have also tested the NGK L1H1 and the NGK LHA. They have a better reputation for longevity in leaded fuel but I have not experienced that in my case since I change the sensors out every couple of years, which is nothing on the longevity scale. The Bosch sensors seem to respond much faster to events than the NGKs do. 4.9 < 4.2 < LHA < L1H1.
2) I have 7 of them on the roadster, one in each cylinder and a single one in the downpipe after the turbo.
3) Trust, but verify. We pull the plugs after every pass and tune accordingly. The sensors are not a magic bullet. They measure oxygen in the exhaust and then make a logical jump to the AFR that would have resulted in that O2 concentration. But an exhaust leak or even a misfire will screw the reading up since both events will allow extra O2 to be present in the exhaust, and the O2 sensor thinks that means you were running leaner than you were.
Just my $0.02, YMMV
x2
Any irregularity in a sensor array/system causes the ecu to misinterpret the situation.
Always, always, always, pull and check your plugs. That evaluation always works. Now that they are affordable, get and use one of those small/tiny inspection cameras. Insert it through the spark plug hole. Get some practice in what your engine looks like undamaged. When something looks "funny", bite the bullet and disassemble it to check. BEFORE, it "disassembles" itself . . . . . .
I still have and use some Welch-Allen optical inspection tools. I can't save the video like I can with the digital camera, but some of that stuff might be pretty cheap on E-bay.
:cheers:
Fordboy
-
1) As the Bosch sensors get lead contaminated they will read leaner and leaner, resulting in a richer tune (from actual). As the lead contamination gets worse they become slower in response time.
2) I can't tell you how many bikes I've tuned after the owner purchased an AutoTune. They end up taking them off their bikes and selling them. I have my thoughts on why they get eronous readings, but I'm not sure why they end up tuning the bikes lean.
-
1) As the Bosch sensors get lead contaminated they will read leaner and leaner, resulting in a richer tune (from actual). As the lead contamination gets worse they become slower in response time.
2) I can't tell you how many bikes I've tuned after the owner purchased an AutoTune. They end up taking them off their bikes and selling them. I have my thoughts on why they get eronous readings, but I'm not sure why they end up tuning the bikes lean.
Ransom,
This bike is only running pump gas (for now)... So what other sources of contamination are there? Im wondering if there any other ways to monitor the afr? As I read more about the O2 sensors, I wonder why they havent been made more accurate, or why a better system isnt developed.
Id be very appreciative of your theories on why they tune lean.
Cheers
Alan
-
Do NOT turn on the heater circuit until you get leaned out and warmed up enough to reduce water droplets into vapor (in your header). Cup position and cup hole arrangement is critical to prevent micro-cracking the heater element. That level of testing is beyond the budget of almost all of us, so keep the heater off when you know its still too cool.
Listen carefully to the exhaust as you adjust that initial tune. It gets quieter and softer tone as it starts getting leaned out. Pay attention to components that vibrate with engine combustion frequency. When things stop shaking, you are getting pretty lean. If it is running pretty clean with these conditions observed, it is probably safe to turn on the heater circuit and start tuning.
Your best chance of water droplet damage is cool engine and lower rpm range.
-
So what other sources of contamination are there?
It's best to think of them just as you would a spark plug. Anything that will foul a spark plug will also contaminate an O2 sensor. Excessively rich mixtures and oil being the most common. Coolant will kill them quick so if you lose an engine the O2 sensor is gone as well. Lead will kill them but it takes a bit longer for it to do it as the effect is cumulative.
If you treat the sensor right they will last for ages, just like they do in a new street car. But if your engine is chewing through spark plugs then it is going to chew through O2 sensors just as fast.
-
I believe that the charging system of most bikes (as well as crappy batteries) do not provide enough amperage for the WB02. That paired with the where the O2s are mounted, usually too close to the exhaust tip (which puts it in the reversion area), all makes for erroneous readings.
-
If a bike can power heated seats, heated grips and heated clothing then it can heat a single O2 sensor.
-
If a bike can power heated seats, heated grips and heated clothing then it can heat a single O2 sensor.
If you look just at the voltage, at low rpms (say 3k) and compare it to 10k, you will find that it drops dramatically. ?? None of my sport bikes have heated seats nor can I use heated clothing with those tiny batteries. Maybe a big cruiser ....
-
Look at the wire sizes on any of the stand-alone O2 systems... that will tell you something about amp draw. 18 and 20 gauge are common. Yes, if you leave the system on overnight you will have a dead battery.... don't ask....
-
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.
-
Carbs solve all of these problems...
-
Wob, wide band O2 works with carbs just as well as EFI... gives you an idea of how your tune is doing.
:-D
-
A wideband sensor was used for three years on the Triumph at Bonneville with considerable dyno tuning done each year. It was used for an air/fuel mixture gage. Mildly leaded gas was used. It worked OK the first year. Halfway through the second year it gave me readings I knew were false. It failed completely during the third year. The bike has carbs so it is no big deal if the gage is not working. Lesson learned is to set up a racing EFI system that does not use closed loop circuitry that depends on an oxygen sensor for input, on a motor running leaded gas.
The other Triumph has a Keihin EFI. A racing map was loaded into it and the oxygen sensors were turned off by use of the software. The system now ran in open loop mode at all times. I took it over the highest mountain pass I could find and it worked OK. The sensors providing input are the tach, the throttle position sensors, an air pressure sensor, a temperature sensor, and the manifold air pressure sensors. The Keihin system does not have a air flow sensor. All worked to trim the mixture so as to adapt it to varying environments. Many folks with racing Triumphs do this. The EFI mapping is done using the tuner's oxygen sensors. The bikes are run in open loop mode with no oxygen sensors.
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.
-
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.
-
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?
-
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
-
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.
-
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.
-
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.
-
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.
-
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
-
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.
-
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.
-
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 damn well better have a few of those magic numbers for all altitudes!
-
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?
-
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.
-
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.
-
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 I’ll 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.
-
At the risk of parroting Sister "Godzilla", parochial principal from my youth:
"Do your homework."
Accurate measuring and/or testing devices are the "backbone" of "good science". Accuracy requires calibration, sometimes constantly, sometimes occasionally.
Just do it.
:cheers:
Fordboy
-
.... Big deal, calibrating 2 sensors is far easier than pulling 8 plugs 3 times a weekend. ....
I agree, calibration is simple and only takes a couple minutes. Remove the sensor from the pipe, disconnect the plug going to it, turn on the power to the sensor for less than a minute, turn it off, reconnect it using the plug and turn it back on and in a minute or so it is re-calibrated correctly to the free air at the time compensating for altitude and it is also now re-calibrated for any wear the sensor has experienced.
(http://www.streetfx.com.au/cms/wp-content/uploads/2013/07/p-1688-innovate_mtxl.jpg)
For about $150 you have the sensor, the gauge and the wideband O2 controller all in one unit. You can also easily customize the LED's that ring the gauge face to turn from green to yellow to red at any air/fuel mixtures you so desire and it is compatible with all fuels and it will interface with most data-loggers,
Sumner
-
Guys, your still skipping over the exhaust pressure issue and the other corrections. Yes, the Innovate still does not correct for these issues, even when you remove the Bosch sensor from the pipe and calibrate it for free air and altitude. I'm only letting you know and you can find it all by reading the Bosch specifications sheets. It's all up to you what you do with the information but please do not go at it blindly and ignore it as it's all there in black and white.
There are plenty of others that allow for free air calibration as well so it's not something that Innovate came up with, nor does it solve the correction issues for them either. The only one that I know of today is the unit in the link I gave you all before.
-
....your still skipping over the exhaust pressure issue and the other corrections....
So exactly how much do those effect the reading? I'm having a hard time understanding the graph you posted. To me it looks like at say 5000 feet they might effect the reading by less than 1/2 of a tenth of a point and if the Innovate can compensate to the free air at 5000 feet then it might be less than that.
If that is the case for our situation and considering we can afford the Innovate it is well worth using it as it easily works with all the other items we are data-logging at the same time,
Sumner
-
Exactly! If you look at the chart; the difference in AFR from Los Angles (sea level) to Bonneville (4,200 ft) is 0.06 AFR! Using 1 bar (sea level) the AFR is 13.24. Go to 4,200ft and the AFR becomes 13.18.
The most serious delta P to consider is a blown application where the pressure can be 2 or 3 bar. A situation where one is hardly relying on just a single sensor to aid in tuning. EGT and plugs are still the important tools in the quiver.
-
Exhaust back pressure? What exhaust back pressure? Aren't these race vehicles with unrestricted, open exhausts? Unless the sensors are pre-turbo, you don't really need to worry about exhaust back pressure unless you've got some kind of restriction which I'm guessing most race vehicles won't have. Now, if going pre-turbo, you'd probably want something like THIS (http://www.aemelectronics.com/?q=products/wideband-uego-air-fuel-controllers/4-channel-wideband-uego-afr-controller).
-
Exhaust back pressure? What exhaust back pressure? Aren't these race vehicles with unrestricted, open exhausts? Unless the sensors are pre-turbo, you don't really need to worry about exhaust back pressure unless you've got some kind of restriction which I'm guessing most race vehicles won't have. Now, if going pre-turbo, you'd probably want something like THIS (http://www.aemelectronics.com/?q=products/wideband-uego-air-fuel-controllers/4-channel-wideband-uego-afr-controller).
This is a very incorrect assumption. We are dealing in Absolute pressure, not gauge pressure here. For those of you that may not know or understand the difference, Absolute pressure is Baro + measure pressure, so that means as you change in altitude you move from one line to another as well as side to side on the chart I provided. So if you connect a gauge to the exhaust and watch the exhaust pulse come down a pipe you are going to see a pressure increase each time the pulse travels down the pipe and thats what you need to know, the absolute pressure when the sensor is read.
Each line on the chart I made for you all, is a different altitude and you follow the curve of the line based on absolute exhaust pressure. You would have to measure your system to see what you have at the location of your sensor but it is not uncommon to see +/- 0.5 bar pressure changes on a open exhaust and that will rise as engine speed and volume increase. So based on the total power output you will and do get different readings. So what you read at say 2000 RPM versus what you read at 8000 RPM can and will have completely different correction facts needed to get an accurate readings.
Also remember what I told you all before, and that is the curve I did was for 13.23 AFR ONLY! As the mixture goes richer the curves change and the amount of mixture change gets greater and greater. As the mixture goes leaner the curves get smaller too, so as you get back to a 14.68 mixture there is next to no curve at all and the correction there really doesn't much matter. Now as you go leaner than 14.68 it all starts back the other direction again but I did not think any of you would much care about the Lean burn side of things. The range of error at a fixed altitude is going to be about 0.63 AFR if you use the whole chart at a mixture ratio of 13.23. That gets greater as you run richer mixtures and smaller as you run leaner mixture up to 14.68.
For the record I am not saying do not use one, what I am saying is understand the tool and what it can and cannot do! I've seen to many people burned by a meter that they believed to be correct and did not understand why they burned a piston when the data told them the mixture was fine.
-
Pre-turbine is an extremely poor installation because of extreme heat and pressure. You would never design such a system unless there was an unusual and compelling reason. The Bosch sensor body temp can never exceed 950 deg F. Pre-turbine temps range 1200-1400 F and pressures are 1-2 bar. That is a fatal environment for any Nertz cell. The WB is installed downstream of all that mess so it can live and give reasonably good AFR.
-
Pre-turbine is an extremely poor installation because of extreme heat and pressure. You would never design such a system unless there was an unusual and compelling reason. The Bosch sensor body temp can never exceed 950 deg F. Pre-turbine temps range 1200-1400 F and pressures are 1-2 bar. That is a fatal environment for any Nertz cell. The WB is installed downstream of all that mess so it can live and give reasonably good AFR.
I run 6 Bosch O2 sensors pre-turbine on our roadster because that way I can see the individual cylinder AFR's and trim accordingly. The max continuous exhaust gas temp allowed is 930C (1700F) and I am below that. The measured back pressure is almost 370kPa and it is compensated for by my controller. I compare those 6 sensors with a 7th one in the downpipe for a sanity check. That one runs in normal pressure and quite a bit cooler than the individual cylinder units. Those individual cylinder sensors are now all going on their 3rd season. The 7th one is new this season because I dropped it ( :-P) and didn't want to risk running it again. The new one reads the same as the old one did.
Our motors don't burn oil and we haven't lifted a head so the sensors are still fine. If we lose an engine I expect to change them all. It's pretty simple really.
-
Exhaust back pressure? What exhaust back pressure? Aren't these race vehicles with unrestricted, open exhausts? Unless the sensors are pre-turbo, you don't really need to worry about exhaust back pressure unless you've got some kind of restriction which I'm guessing most race vehicles won't have. Now, if going pre-turbo, you'd probably want something like THIS (http://www.aemelectronics.com/?q=products/wideband-uego-air-fuel-controllers/4-channel-wideband-uego-afr-controller).
This is a very incorrect assumption. We are dealing in Absolute pressure, not gauge pressure here. For those of you that may not know or understand the difference, Absolute pressure is Baro + measure pressure, so that means as you change in altitude you move from one line to another as well as side to side on the chart I provided. So if you connect a gauge to the exhaust and watch the exhaust pulse come down a pipe you are going to see a pressure increase each time the pulse travels down the pipe and thats what you need to know, the absolute pressure when the sensor is read.
Each line on the chart I made for you all, is a different altitude and you follow the curve of the line based on absolute exhaust pressure. You would have to measure your system to see what you have at the location of your sensor but it is not uncommon to see +/- 0.5 bar pressure changes on a open exhaust and that will rise as engine speed and volume increase. So based on the total power output you will and do get different readings. So what you read at say 2000 RPM versus what you read at 8000 RPM can and will have completely different correction facts needed to get an accurate readings.
Changes in elevation and changes in exhaust pressure aren't the same thing as your chart shows. Unless you're racing up Pikes Peak, one can generally assume elevation changes are fairly minimal thus the impact on measure AFR variance is pretty small. Also, a change in exhaust pressure from 2000 rpm to 8000 rpm isn't really all that significant when you're racing at WOT for extended periods of time. The point being that exhaust pressure is largely the same (and I've personally never seen an EBP of 7psi on an open exhaust) when you care to look at it which is at high rpm, high power, high exhaust flow and not at idle. So your measured AFR changed by a tenth of a point at most between idle and WOT. Does that really matter? These aren't OEM cars trying to pass stringent emissions regulations - these are race vehicles running at comparatively rich AFRs. A tenth variance in AFR shouldn't be hurting anyone tuning/running a performance engine that's running rich anyways and I think the aftermarket UEGO controller manufacturers realize this and have thus decided that minor changes in pressure/elevation are... minor.
-
Edit . . . I run 6 Bosch O2 sensors pre-turbine on our roadster because that way I can see the individual cylinder AFR's and trim accordingly. The max continuous exhaust gas temp allowed is 930C (1700F) and I am below that. The measured back pressure is almost 370kPa and it is compensated for by my controller.
Because of cost I never installed individual AFR on each header. Although I agree I would love to have perfect AFR for each cylinder. I am converting to a lower cost alternative of running EGT at each cylinder and a single AFR on each side of the motor. It is not as good as your set-up but the EGT will point to any problematic cylinder and the AFR (even though it is averaging all 4 cylinders will tell me if the EGT-cylinder-of-interest is rich or lean). I also don’t have EFI with the ability to trim individual cylinders. Sounds like you have a wonderful Motec system!
I am surprised at the life and accuracy you are getting from your installation pre-turbine. I know there are tricks you can do to heat-sink the sensor body temps but your numbers are way beyond what my brand recommends. I am following these Innovate installation instructions for fear of destroying my sensor.
The Bosch LSU4.2 wide-band O2 sensor (shipped as part of the LM-1 kit) is rated to operate at an exhaust gas temperature of < 1300 degrees (F), and a sensor housing temperature of < 900 degrees (measured at the bung) for maximum accuracy and control. When either of these operating temperature ranges is exceeded, the sensor can no longer be accurately controlled. Further, operating at or over these temperatures for any length of time can significantly reduce the lifetime of the sensor.
http://www.innovatemotorsports.com/support/faq.php
What system are you running?
-
I'm running 2 of the AEM 4 channel UEGO systems Nathan linked to earlier. They have the option of pressure compensation which I am using since I am pre-turbine.
The numbers I quoted are the ones in the most recent Bosch LSU 4.2 spec I have on hand.
2.2 Operating temperatures
Exhaust gas at sensor element: ≤ 930°C (1,706°F)
Hexagon of the sensor housing: ≤ 570°C (1,058°F)
2.3 Maximum temperatures (max. 250 h accumulated over lifetime)
Exhaust gas at sensor element: ≤ 1030°C (1,886°F)
Hexagon of the sensor housing: ≤ 630°C (1,166°F)
Notes:
If the exhaust gas temperature of 930°C is exceeded, the heater power must be switched off. In this case the accuracy of the sensor signal is limited.
If the max. gas temperature exceeds 930°C or hexagon temperature exceeds 570°C, the use of a longer thread boss is recommended.
If the operating temperature is exceeded (within the max. temperature limits) for more then 10 minutes without break, the sensor function might be affected during this time.
The AEM multi-channel systems come with special extended and finned bungs specifically designed for primary runner installation.
-
Exhaust back pressure? What exhaust back pressure? Aren't these race vehicles with unrestricted, open exhausts? Unless the sensors are pre-turbo, you don't really need to worry about exhaust back pressure unless you've got some kind of restriction which I'm guessing most race vehicles won't have. Now, if going pre-turbo, you'd probably want something like THIS (http://www.aemelectronics.com/?q=products/wideband-uego-air-fuel-controllers/4-channel-wideband-uego-afr-controller).
This is a very incorrect assumption. We are dealing in Absolute pressure, not gauge pressure here. For those of you that may not know or understand the difference, Absolute pressure is Baro + measure pressure, so that means as you change in altitude you move from one line to another as well as side to side on the chart I provided. So if you connect a gauge to the exhaust and watch the exhaust pulse come down a pipe you are going to see a pressure increase each time the pulse travels down the pipe and thats what you need to know, the absolute pressure when the sensor is read.
Each line on the chart I made for you all, is a different altitude and you follow the curve of the line based on absolute exhaust pressure. You would have to measure your system to see what you have at the location of your sensor but it is not uncommon to see +/- 0.5 bar pressure changes on a open exhaust and that will rise as engine speed and volume increase. So based on the total power output you will and do get different readings. So what you read at say 2000 RPM versus what you read at 8000 RPM can and will have completely different correction facts needed to get an accurate readings.
Changes in elevation and changes in exhaust pressure aren't the same thing as your chart shows. Unless you're racing up Pikes Peak, one can generally assume elevation changes are fairly minimal thus the impact on measure AFR variance is pretty small. Also, a change in exhaust pressure from 2000 rpm to 8000 rpm isn't really all that significant when you're racing at WOT for extended periods of time. The point being that exhaust pressure is largely the same (and I've personally never seen an EBP of 7psi on an open exhaust) when you care to look at it which is at high rpm, high power, high exhaust flow and not at idle. So your measured AFR changed by a tenth of a point at most between idle and WOT. Does that really matter? These aren't OEM cars trying to pass stringent emissions regulations - these are race vehicles running at comparatively rich AFRs. A tenth variance in AFR shouldn't be hurting anyone tuning/running a performance engine that's running rich anyways and I think the aftermarket UEGO controller manufacturers realize this and have thus decided that minor changes in pressure/elevation are... minor.
You may want to invest in a fast reading absolute pressure gauge, and I think you will see things differently. You will need something down in the less than 100 Ms response time range, better is < 50 Ms. If your gauge isn't showing pulsing of the pressure in an open type exhaust then you gauge is most likely reading to slowly. A standard pressure gauge will not do the trick here. Also remember to think in terms of absolute pressure as that is what were working with, not gauge pressure. As for you thinking it is only 0.1 AFR your looking at, I have to disagree with you as I have personally seen much more than that. You also have to deal with guys not running on gasoline, that will not be running around the 13.23 AFR level chart I posted, the alcohol engines are running typically down around 6:1 AFR and the errors get much larger there.
Look everyone can do what they can and I've only posted this so that you all know. What you do with it is up to you, but some of us had to learn it the hard way.
-
One interesting tidbit I'll add: I have 3 LM1 tuners from innovate, and if I take the same cables and the same O2 sensor and calibrate it on each LM1 unit, all 3 will have different readings, in a range of about .7 AFR from lowest to highest. I bought all 3 new, and all 3 have the same internal settings. 2 of them have been sent in for repairs, sent back with the exact same (different from each other) calibrations. be wary of your gauge readings, even if the sensors are new. What it comes down to is that they are great for comparison, but not great for perfect data. Use other sensors such as EGT, plus spark plug color, dyno results, and common sense to make the most of your tune. Data you gain from any one sensor will never be the inherent truth. If you heldd that state of mind, records will prove very, very difficult at best. :cheers:
-
What sensors work best with leaded gas having a small dose of top end lube?
-
What I have found to work best when using leaded gas is to NOT use a new sensor! Sounds screwie right, but a used sensor seems to last longer when using leaded gasoline. I take a good new one and run them for about 10 hours only on unleaded. Then after that make them for use with leaded fuel. While not the end all be all, it does seem to make them last with a fair reading for about twice as long for some reason. While I do not know why it, has proven itself time and time again, for the past 25 years of doing it.
So take it for what it's worth.
-
Thanks, Steve. That is good to know. I will "season" the sensors on my street bike using unleaded pump gas before I put them on the race bike.