Valuable information about narrowband oxygen sensors...

[gmtech16450yz]

I'm having a discussion elsewhere about narrowband readings and I thought I'd copy/paste what I was saying here. I know common internet knowledge is to NOT use narrowband data for tuning, but I strongly disagree. They can absolutely give you valuable data if you know what you're looking at.

Anyway, here's my posts on the subject...


Hey this is a big HEADS UP for you guys that don't have widebands, or have widebands but aren't logging with them...

Look at your narrowbands!!! I know everyone will say "You can't use narrowbands for tuning". Well in case you haven't noticed yet, I'm not everyone. lol. Well guess what, you CAN use narrowbands as a very good indication of WOT mixtures, especially when they're way off. Somebody just sent me a log of some WOT runs, but they didn't have their wideband logging in v3.0 yet. They did have their narrowbands being logged though. At WOT the narrowbands were reading in the very low .800's. That's hella lean! Narrowbands should be reading in the high .900's when WOT fueling is closer to optimum.

What would you say high 900s equates to lambda wise being optimal?

Do you know you can trust the accuracy of a narrowband , especially one that may have considerable use as it gets further away from 450mv?

Did you mean CAN or CAN'T? I believe you can. I look at narrowband traces in logs all the time.

Good question on the Lambda relationship. Here's a couple screen shots of a MAJOR fuel pump issue. It should be blatently obvious to see what's happening even for the guys who have never looked at HPT logs. I took a shot at the beginning of the pull and the end so you can see the voltages compared to the Lambda readings. They do end up being a viable indication of mixture, and for a LOT of guys using slow widebands, they react WAY faster so you can see transient issues that you wouldn't be able to see in their widebands.

BTW, look at the fuel pressures. So if ALL you had to go by in this log was the narrowband readings, would you be able to tell there was a major issue? Absolutely. Lemme know if anyone needs anything in these screenshots explained.



[/QUOTE]

I agree they can be an indication that fueling may need to be looked at whether physical or in the tune. What it really does though is just point out the need to get a wideband on it to see what is really going on. I see a lot of degredation in the narrow bands over time which can skew their readings quite a bit.

If a narrowband is "degraded", it's faulty. If it can't produce up to 1 volt, it's faulty. Obviously a reading from a faulty sensor would be useless. Modern oxygen sensors are extremely reliable and rarely degrade to a point of "working" but not reading correctly. It would either be setting a code or causing closed loop fueling issues if it was that far degraded.

If it's a properly working narrowband sensor, it's readings ARE usable, repeatable, transferable and valuable. You gotta remember my training and job experience ever since my first class at the GM Training Center in 1983 has depended on my understanding how oxygen sensors operate. (I still remember what the class was about, it was a week long class about the Cadillac Digital Fuel Injection. Pretty cutting edge stuff for '83!) I've been looking at oxygen sensor voltages damn near everyday for 33 years now, it's my job. lol.

My big point here is that MANY guys don't have widebands, or aren't logging them for various reasons. Sure, it would be ideal if you had an ACCURATE wideband in every car, but that's not gonna happen. And I put accurate in caps because I also believe, damn, I KNOW that a large percentage of those guys with widebands are getting inaccurate information anyway. The sensors are either too slow or the offsets aren't set up correctly. The latter is the most common problem and can result in wideband readings that aren't even close to actual exhaust content. If you understand how to read narrowbands, it can, and often does tell you if your wideband is even in the right ballpark in IT'S readings.[/QUOTE]

[jtrosky]

Stupid question - why don't cars come with wideband sensors from the factory (instead of narrowband sensors)? It just seems that something like a sensor that controls proper air/fuel mixtures would be an extremely important sensor to have!? I realize that there is a cost difference, but I would think that it would be such a minor difference if installed at the factory. Or does this actually emphesize your point - that narrowband sensors are sufficent for this task! :-)

I have a LOT to learn about fueling, but it just seems that having accurate O2 sensors (under all circumstances) would be such a critical part of the equation....

[10_SS]

Stupid question - why don't cars come with wideband sensors from the factory (instead of narrowband sensors)? It just seems that something like a sensor that controls proper air/fuel mixtures would be an extremely important sensor to have!? I realize that there is a cost difference, but I would think that it would be such a minor difference if installed at the factory. Or does this actually emphesize your point - that narrowband sensors are sufficent for this task! :-)

I have a LOT to learn about fueling, but it just seems that having accurate O2 sensors (under all circumstances) would be such a critical part of the equation....

Some cars do, I think VW uses them on some gas engines. But they cost too much and often need replacement/calibration and you can save tons money doing what people do with narrow bands. I would bet some supercars have widebands (Bugatti Veyron).

The Narrowband does control the proper air/fuel ratio buy switching back and forth, rich of stoich, and lean of stoich. They are very accurate at 14.67 for gas. Narrowbands are much more robust than widebands... less chance for failure, etc. Nowadays cars monitor fuel pressure and they know the flow rate of fuel based on the injector pulse and they get the Fuel Trims from the 02 sensors so they know how the system is running... example if the system is adding 5% fuel in closed loop using Narrow bands, then this carries over into WOT/PE mode.

YOu can actually feel narrowbands switching rich and lean if you have a manual trans or an auto that has a locked torque converter... as your accellerating mildly you can feel little swings in power... that is the air fuel ratio switching rich/lean. YEs wideband would be MUCH better overall... but much more $$. When an automaker can save $1 per car... that is a huge savings over a year... if they have to spend $5 or $10 more PER CAR for a Wideband system compared to a narrowband system and in the end get the same MPG, reliability, and power... well you do the math.

[gmtech16450yz]

Thanks 10_SS! You saved me a bunch of typing! And no, that absolutely wasn't a stupid question jtrosky, it was actually an excellent question.

As 10_SS stated, narrowbands do a very good job of keeping the mixture at stoich by switching back and forth between too rich and too lean. There is another big reason that most manufacturers have stayed with narrowbands, and that's the catalyst operation. A 3-way cat NEEDS the mixture to be both too rich AND too lean, that's how it operates. The very short explanation is that if what's going into the converter was perfect combustion, it wouldn't have the elements needed to control NOx. So since the cat needs the mixtures to swing back and forth between too rich and too lean, a switching oxygen sensor works great for that.

And yes, some cars already have widebands from the factory. The Bosch E69 used in the GM Ecotecs like the LNF have factory widebands. Not only that, they run in closed loop at all times, even during WOT. If LS engines had closed loop WOT fuel control there would probably be half of the blown engines that there are now. When you do a mod that makes a constant closed loop engine too lean, it doesn't blow up because even at WOT it knows it's lean and richens the mixture automatically. (In general terms obviously.) The fuel control in a Direct Injected Bosch E69 LNF is amazingly accurate. It makes tuning an LS engine seem caveman crude in comparison. LTFT's are normally within -5 to +5%, even from the factory. I usually shut off LTFT's because STFT's are plenty enough control in those engines, and even those can be tuned to stay within a -10 to +10% span. Watching commanded and actual Lambda in the logs, they're almost always exactly the same. Oh and they use Lambda in those ECM's too, none of this AFR or EQ Ratio stuff. lol.

[jtrosky]

Thank you both - great explanations and information!

After reading what I've read on here and other forums, I always thought that is was strange how my 2012 Impala (3.6L LFX direct-injected engine) *and* the V6 Camaros come tuned stock with their PE thresholds set to 95% torque and 90% pedal - so the vast majority of the time, they are in closed-loop - even during almost-WOT. I also swear that I've noticed less KR when tuned this way.

Do you guys think that it's tuned this way just to be "safer"? Most people seem to like to bring PE in MUCH earlier that these stock thresholds - I never really understand why if the car can ensure proper fueling in closed loop.... This seems kinda, sorta related to what you are saying some other cars do.

So, any reason to change this to bring PE in ealier or are you better off leaving the PE thresholds at stock values?

Don't want to derail this thread, but just thought I'd bring that up to get some input...

Thanks - like I said, geeat info, especially for novices like myself! Most people act like widebands are absolutley essential - but maybe that is starting to change with newer-technology engines and comuter systems?

[mbray01]

I will add this, there are a lot of really good tuners out there that tune with narrowbands, but claim they only tune with widebands, just for the sake of not having to argue with the internet police about how inaccurate narrow bands are. I for one use narrowbands most of the time. A properly set up scanner and "tuning" file will yield very impressive results vs using a wideband. Granted a wideband is the most accurate at wot, but if pe is turned off and you have everything mapped correctly using narrowbands and fuel trims, then pe is nothing more than a math equation, and should be dead nuts on. if its off, there is probably another concern elsewhere.
Now this is on na motors, power adders get a little fuzzy with narrowbands, and I do always use a wideband for safety sake, and besides, I really don't want to buy a customers motor just to prove it can be done.
a second note, when I log a wideband it is always installed in a close to the factory narrowbands as possible, or if I cannot install another bung, than I remove the narrowbands and install the wideband there.
I never use a tailpipe wideband for tuning, but that is my personal preference, as I "Feel" like the transfer time is too slow on an already slow wideband when in the end of the pipe, not to mention the increased risk off fresh air contamination
but that is my .02, and of no way am I implying that my way is the way it has to be done,

[schpenxel]

TO the previous question--BMW has been using wideband O2 sensors since at least 2004, so it isn't that they can't be used..

Ford also puts them on Mustangs. Possibly others, but the point is they CAN be used, some OEM's (cough cough **GM**) have just been slow to swap over to them.

I do agree with at least looking at NB readings... I've noticed my front NB readings @ WOT are damn near identical.. literally within a few mV of one another, which makes me feel pretty comfortable in saying AFR's between bank 1 and 2 are very close to the same. If I saw them far off from one another I'd probably add a wideband to the other bank just to see what is going on.

I certainly wouldn't personally depend on them, but I do think they can give you some level of information.

Thank you both - great explanations and information!

After reading what I've read on here and other forums, I always thought that is was strange how my 2012 Impala (3.6L LFX direct-injected engine) *and* the V6 Camaros come tuned stock with their PE thresholds set to 95% torque and 90% pedal - so the vast majority of the time, they are in closed-loop - even during almost-WOT. I also swear that I've noticed less KR when tuned this way.

Do you guys think that it's tuned this way just to be "safer"? Most people seem to like to bring PE in MUCH earlier that these stock thresholds - I never really understand why if the car can ensure proper fueling in closed loop.... This seems kinda, sorta related to what you are saying some other cars do.

So, any reason to change this to bring PE in ealier or are you better off leaving the PE thresholds at stock values?

Don't want to derail this thread, but just thought I'd bring that up to get some input...

Thanks - like I said, geeat info, especially for novices like myself! Most people act like widebands are absolutley essential - but maybe that is starting to change with newer-technology engines and comuter systems?

Some of the GM trucks do the same thing or worse.. they'll run at 14.7:1 @ WOT for long periods of time without any issues.

I think GM probably does it more to save fuel than anything else. I could be totally wrong though. Running around 0.85 lambda typically makes the most power, at the expensive of an extra 15% fuel.

[gmtech16450yz]

I will add this, there are a lot of really good tuners out there that tune with narrowbands, but claim they only tune with widebands, just for the sake of not having to argue with the internet police about how inaccurate narrow bands are. I for one use narrowbands most of the time. A properly set up scanner and "tuning" file will yield very impressive results vs using a wideband. Granted a wideband is the most accurate at wot, but if pe is turned off and you have everything mapped correctly using narrowbands and fuel trims, then pe is nothing more than a math equation, and should be dead nuts on. if its off, there is probably another concern elsewhere.
Now this is on na motors, power adders get a little fuzzy with narrowbands, and I do always use a wideband for safety sake, and besides, I really don't want to buy a customers motor just to prove it can be done.
a second note, when I log a wideband it is always installed in a close to the factory narrowbands as possible, or if I cannot install another bung, than I remove the narrowbands and install the wideband there.
I never use a tailpipe wideband for tuning, but that is my personal preference, as I "Feel" like the transfer time is too slow on an already slow wideband when in the end of the pipe, not to mention the increased risk off fresh air contamination
but that is my .02, and of no way am I implying that my way is the way it has to be done,

Hahahaha! I loved that comment! So true though. I get in more trouble with the internet police than I do with the real police. I just have a thing about false information being passed around so much that it appears to be true. Doesn't mean it is. And thanks a ton for your reply, it was dead on. Imagine that, a 15 year master tech and GM World Class Technician having the right idea? Amazing! lol. Not really. I know how much training it takes to be a GM WCT. I know you've had to sit through and watch a ton of courses dealing with issues like oxygen sensor operation. It's hard to not pick up a few things in all that training and experience.

FWIW, here's a screen shot from the same car that I was logging above. This is after fixing the fueling issue. Gee, does that narrowband reading look a little different now? Again, if that was all you had to go by, which is the case a lot of the time, it would absolutely be useful information. Narrowband oxygen sensors are extremely fast and still PLENTY accurate even at the ends of their ranges. It's the speed difference between narrowbands and your average wideband that is where you pick up on problems. I'm sure most "tuners" have no idea how much information they may be missing by ONLY looking at wideband readings.


(Oh yeah, that was a 2.8 second 60-100 run! Any of you guys that have 1/4 mile passes logged, pull your 60-100 times out of them. It's a really good indicator of power without having to go to the track or dyno room.)

[gmtech16450yz]

I'm adding another screen shot here in a new post because I don't want it getting missed. This is a zoomed in version of the exact scan above. Look at the red trace, that's the stock narrowband sensor. Now look at the white and yellow traces, those are two of the fastest (reasonably priced) widebands on the market today. They are two AEM 30-0300's being read into HPT through the CAN network. They are WAAAAAAYYYYYYY faster than the one I replaced in this car, which was also one of the fastest widebands, the PLX LSU4.9.

Anyway, look at the difference in switching times between the narrowband and the widebands. After the throttle was cut, it took those hella fast AEM widebands an ADDITIONAL 30ms to react to the change in mixtures. It also took that same amount of difference for it to fully switch from rich to lean, which is actually impressive for a wideband. So basically the mixture went from very rich to very lean and the narrowband saw and reported it .030 seconds faster than one of the fastest widebands you can buy and setup. BTW that's 3 frames in the new HPT software, which is also HELLA cool!!! Thanks again Keith!!! In the old software you probably would have missed that whole difference in switching times.

Very interesting, at least to me! Enjoy...

[schpenxel]

I gotta get me one of those new AEM's!

[dr.mike]

Nice data

Is the NB being polled at the same 100Hz? The steps look longer, zoomed in.
Also, are the NB and wideband sensors at the same location?
Of course, the NB will ( or should ) always be a bit faster, as the WB sensor uses an internal NB for a reference.

This maybe gilding the lily. But, 30ms is slower than I have ever seen an AEM 30-0300/310 react. Which is still faster than anything else. But, still

[gmtech16450yz]

Nice data

Is the NB being polled at the same 100Hz? The steps look longer, zoomed in.
Also, are the NB and wideband sensors at the same location?
Of course, the NB will ( or should ) always be a bit faster, as the WB sensor uses an internal NB for a reference.

This maybe gilding the lily. But, 30ms is slower than I have ever seen an AEM 30-0300/310 react. Which is still faster than anything else. But, still

Thanks Mike! I was hoping you saw this thread, your input is extremely valuable obviously. You clearly have the Engineer/math side (which I suck at) and I have the hands-on experience, seat-of-my-pants side of all of this!

Excellent questions of course, I already thought about the actual physical location of the sensors. The B1 wideband is in an added bung very close to the B1 narrowband. The B2 wideband is in the stock narrowband location since this car isn't actually using the narrowbands anyway. So that's not an issue since the B1 sensors are close to each other and we also have a narrowband and a wideband in stock manifolds and in the stock positions. Can't get any better than that at ruling out those variables! Oh and both the widebands are dead on even 90% of the time.

And yes, all 3 sensors are being polled at the fastest rate. Both widebands were set at 100Hz and the narrowband was at the default which is 0ms or "fastest". I set it to 10ms just now but it shouldn't make any difference. If anything it might be slower?

Thanks for commenting! And yeah, I thought the data in those screen shots was pretty cool. We are going to learn SO much more with this newer software being so much faster. Damn, I'll be able to get my 60-100 times accurate down to 10ms now!

[gmtech16450yz]

HOLY CR@P!
Ok so I was curious at how much difference there really is in the new v3 software vs. 2.24. I opened the same file in 2.24 and also in 3.0.59 and compared the data points in one transition between full throttle and when the wideband reacted. (Just a random reference point but one I could duplicate easily in both programs.) Ok so in 2.24 there were 8 "steps" or data points in that transition that lasted only about 650ms. Remember that number, it was 8.


















The same section of data in v3 had 64 "steps" or data points!!! Dayamm! In case you're reading this, does that make sense Keith? V3 has data every 10ms, and it looks like 2.24 had it every 78ms? Whatever the numbers are, v3 is hella fast!

edit- those numbers were from an E69 log. I just compared a couple of E67 logs and it looks like the old 2.24 had a data point about every 48ms and v3 was still at 10ms. Clearly it depends on what's being logged and from what kind of ECM. But it still looks like v3 logs way more data points from the same ECM's that 2.24 did.

[rao]

I'm not so sure on this.

I made up a graph of the wideband on bank 1 vs the narrow band on bank 1. I applied it to a 45 minute cruise.

Attached is a sreadsheet showing the actual NB results and the hit counts.

[gmtech16450yz]

I don't know, Mike's gonna have to field the spreadsheet questions! lol.

Looking at your data though, it seems to agree with the point I made that started this whole discussion...

Yes of course ____, having a wideband also is ideal. But for the huge percentage of guys driving modified cars without LOGGING their widebands, the narrowbands are valuable information. I might have just saved a member from blowing his engine because of them. His was at .800 at WOT. Looking at my screenshots, he could have been at damn near Lambda 1.0!!!!!! I would say the narrowband is definitely telling us something there.

So yeah, if this guy had narrowband readings in the high .700's, low .800's, he WAS damn near lambda. From your data, he would have been around 14.4 or 14.5 afr. This is my point for the specific issue that brought this all up...

8 out of 10 "tuners" would have looked at his log and said either "You need a wideband" or "Looks ok except for some KR". I looked at it an IMMEDIATELY emailed him and told him to be VERY careful because he's in danger of blowing a $13k LSA. Yes, I also told him to get that wideband hooked up and reading in v3, but even without it, the narrowbands showed something was WAY off. This is my whole point. Yes having a wideband is great, but you don't always have that data. And even if you do, you really need the data that the narrowbands give as a "checks and balances" to the whole picture. How many guys have blown their engines because they didn't know they were going lean? Every single engine comes with narrowband oxygen sensors that can be logged. Not every modified engine has a working, accurate, fast wideband that's actually being logged. Very few do actually.

[RandomEnthusiast]

Here's a fun fact. Ever heard of a planar o2 sensor? Stock o2 sensor on most subarus and quite a few toyotas. They aren't really wide band but will accuratley read from about 12:1 afr to 16:1 afr in my experience. A lot of people in the subaru world demand widebands but I tuned according to planar voltage on them. They are 5 volt sensors to. I've never had an issue using them with stock ecm.

[schpenxel]

Yeah from like 250 to slightly under 800mV you might as well be at lambda. My NB's swing that far all the time and the WB only changes 2% at most each way.. it's very very little until you get in the mid to upper 800mV's

[10_SS]

the data in those screen shots is not actual data in most cases... you may be getting interpolated data between data points, so some channels with fast data may be actual on the charts, and some channels with slow data can be very misleading, you need to watch the "channel" data for updates. This is where I prefered 2.24.

Regarding the GM Truck PE mode... I have a 31' motorhome with the 8.1L, and to save gas and reduce emissions, PE is delayed at WOT for something like 20-40 seconds initially, it has no knock at WOT when out of PE, but the more I WOT it, the faster it enters PE. I think they calculate cyl temp or watch IVT and as it rises, then they bring in richer fueling to lower temps, and reduce spark knock. It's not really a performance motor, lower compression, torque cam, etc.

Anything performance related you want PE on every time... especially boosted. I think most people know NB 02's can work ok for general info. I wonder how the CAN bus data from the Wideband is synced with the Can Bus data from the ECU... there could possibly be a bit of an offset there also.

Regarding tuning, non-PE I always use Narrowbands.. . PE I use Widebands... but also make sure the 02's appear to be above 900mv since those are averages... 898mv vs 870mv... not a big difference,, but Wideband says 12.0 vs 13.5. And we know they bounce around quite a bit which makes it hard.
911=11.5
898=12.0
886=12.5
879=13.0
870=13.5
844=14.0
732=14.7
440=15.0

Furthermore, you will notice if you make 3 runs, compare the WB to the NB 02's, or different days, the NB 02s values seem to drift a bit, so it's best to use them as a sanity check for the WB.

[schpenxel]

I've read that the temperature of NB O2 sensors makes their output vary at lean/rich ends of the spectrum, so that could explain the drift you mentioned.

[gmtech16450yz]

the data in those screen shots is not actual data in most cases... you may be getting interpolated data between data points, so some channels with fast data may be actual on the charts, and some channels with slow data can be very misleading, you need to watch the "channel" data for updates. This is where I prefered 2.24.

Regarding the GM Truck PE mode... I have a 31' motorhome with the 8.1L, and to save gas and reduce emissions, PE is delayed at WOT for something like 20-40 seconds initially, it has no knock at WOT when out of PE, but the more I WOT it, the faster it enters PE. I think they calculate cyl temp or watch IVT and as it rises, then they bring in richer fueling to lower temps, and reduce spark knock. It's not really a performance motor, lower compression, torque cam, etc.

Anything performance related you want PE on every time... especially boosted. I think most people know NB 02's can work ok for general info. I wonder how the CAN bus data from the Wideband is synced with the Can Bus data from the ECU... there could possibly be a bit of an offset there also.

Regarding tuning, non-PE I always use Narrowbands.. . PE I use Widebands... but also make sure the 02's appear to be above 900mv since those are averages... 898mv vs 870mv... not a big difference,, but Wideband says 12.0 vs 13.5. And we know they bounce around quite a bit which makes it hard.
911=11.5
898=12.0
886=12.5
879=13.0
870=13.5
844=14.0
732=14.7
440=15.0

Furthermore, you will notice if you make 3 runs, compare the WB to the NB 02's, or different days, the NB 02s values seem to drift a bit, so it's best to use them as a sanity check for the WB.

Hate to say it but I don't agree with a couple of your points here.

First off, what you're talking about as far as data updates being faster in the Channels vs. Chart, that's actually a problem WITH 2.24. V3.0 updates chart data at a speed of 10ms. How much interpolating do you think is happening in less than 10ms? lol. Not much. I can guaranty you are missing WAY more data using 2.24 than you are using 3.0. Did you read my comments on the 8 data points vs. the 64 in the new software? You're seeing 8 points of data in 2.24 while we're seeing 64 in 3.0. And even that's in a 650ms clip.

As far as the CAN bus, I'm no computer Engineer but I'm pretty darn sure the CAN bus is digital. "Offsets" are only an issue when you're dealing with analog. Digital is digital, it's hard to mess up 1's and 0's.

And as far as which sensor is more repeatable or reliable, again I'm no Engineer but I'm gonna say you will get more repeatable results from a digital narrowband than an aftermarket wideband hooked up through an analog 0-5v conversion.


I think one of the problems we have when we're talking about narrowbands is guys think, or want them to be a linear sensor like a wideband. They're not. That's not how they work. You're never going to be able to match a full range of wideband readings with a full range of narrowband readings. I think that's what RAO was trying to convey or was the problem he saw with his spreadsheet??? Data points or "hits" will be all over the board with the narrowbands, that's exactly what the ECM needs to see to figure out what the mixtures are. Especially in normal driving, low voltages will have more hits simply because of things like DFCO.