The Wide Band....how do we really know...

[Redline Motorsports]

I am at my ends wit with the WB! How do we really know if its accurate? I have two LM-1's and a Autronics Model B, and they never read the same. the Autronics is a high speed 5 wire UEGO style that is integrated into my dyno and is said to be fairly accurate. One of my LM-1's is brand new.

I am not that all convinced that the "free air" calibration synch's these devices. There has got to be a way to calibrate a WB that is more reliable. Something that can produce a controled AFR to match to. I was think that if you take a fairly new car ,let it warm up and go into closed loop, theoretically it should be emitting an AFR of 14.7:1. If we know that an OEM narrow band is accurate at that value, then the WB should read the same.

All these variations are really starting to screw with my head as I am loosing all confidence in all of them. :nixweiss:

I am almost at the point of searching out a high end unit, spending the money and get my piece of mind back! Yesterday, as a test, I stuck both WB's in the tail pipe of a car. One read 13.65 (Autronics) the other read 15.2 (LM-1). Keep in mind that the EFI Live has nothing to do with this.

Anyone else feel the same at times??

Howard

[Tordne]

When I got my PLX WB I went to the place that originally tuned the car and validated it's accuracy with a MoTeC unit, which I assume would have been pretty expensive. Can't comment on accuracy of course, but at least they were spot on one another :)

Good thing with PLX is that they do self calibrate and you don't have to piss around with the voltage configuration etc!

[TAQuickness]

have you tried swapping them from bank to bank to see if the problem follows :D:D:D

There is quite a bit of slop in automotive tolorances.

[Redline Motorsports]

have you tried swapping them from bank to bank to see if the problem follows :D:D:D

There is quite a bit of slop in automotive tolorances.

The problem with that theory with respect to this is that I had both WB in the same tail tip!

At one point I had the Autronics in the bung after the header collector and the LM-1 in the tail pipe. The Autronics at idle was reporting an idle AFR of 21:1. The motor is bone stock in which we just installed a ProCharger. There was no way it was that lean and idling rock solid at 650!

My point is one; how can you confirm and AFR to calibrate your WB?

Do you disagree that a stone stocker should produced a AFR of 14.7 +/- .1 at idle and that can at least verify that when your WB reports the same that we are at least in the ballpark?

You ever heard of a Hariba (I think its spelled wrong) AFR meter?

[5.7ute]

From what I understand the only way to check the calibration properly is with a known gas from a calibration cylinder. I have been having the same thoughts as the LM-1 free air calibrates to an oxygen content of 20.9 where as our Sniffers etc (Hazardous entry tooling) only read 19.8.

[Redline Motorsports]

From what I understand the only way to check the calibration properly is with a known gas from a calibration cylinder. I have been having the same thoughts as the LM-1 free air calibrates to an oxygen content of 20.9 where as our Sniffers etc (Hazardous entry tooling) only read 19.8.

Exactly. My Autronics unit reads 76:1 when the o2 is hanging on the side of the dyno cabinet. Why they make the resolution go that deep into lean is beyond me. The LM-1 must assume that if the sensor is in "free air" it must read 20.9. That 20.9 if I am not mistaken is not AFR but a percentage reading isn't it?

Howard

[Alvin]

I have to say that every LM1 I have tried on our dyno has been rediculously off.. Around .5 of a point.

Then you hear people say the cars go .5 points lean on the street.. Is it the wideband or the extra load? :)

[Redline Motorsports]

I can't see it being the extra load. The PCM is fueling based upon the the load it measures and looks up the appropriate fuel. I'd lean towards the LM-1!:bash:

[purrvert]

Exactly. My Autronics unit reads 76:1 when the o2 is hanging on the side of the dyno cabinet. Why they make the resolution go that deep into lean is beyond me. The LM-1 must assume that if the sensor is in "free air" it must read 20.9. That 20.9 if I am not mistaken is not AFR but a percentage reading isn't it?

Howard

Here's a quote below. 20.9 is the percentage of oxygen in air. The 76:1 reading is baffeling but close to an inverted reading.

"The atmosphere begins at sea level, and its first layer, the troposphere, extends from 8 to 16 km (5 and 10 mi) from Earth’s surface. The air in the troposphere consists of the following proportions of gases: 78 percent nitrogen (http://encarta.msn.com/encyclopedia_761568106/Nitrogen.html), 21 percent oxygen (http://encarta.msn.com/encyclopedia_761577400/Oxygen.html), 0.9 percent argon (http://encarta.msn.com/encyclopedia_761577486/Argon.html), 0.03 percent carbon dioxide (http://encarta.msn.com/encyclopedia_761574216/Carbon_Dioxide.html), and the remaining 0.07 percent is a mixture of hydrogen, water, ozone, neon, helium, krypton, xenon, and other trace components. Companies that isolate gases from air use air from the troposphere, so they produce gases in these same proportions"

[5.7ute]

I just finished auto ve in mine & set the car back into semi open loop commanding 14.63 in the around town areas. I kept the wide band hooked up & went for a drive & the o2 sensors were switching between 14.9 &15.1 to 1. Makes me wonder which one is reading out.
At the end of the day I dont suppose it matters as long as you tune with the one tool. I just wouldnt want to be pushing towards the lean end of the scale.

[purrvert]

I just finished auto ve in mine & set the car back into semi open loop commanding 14.63 in the around town areas. I kept the wide band hooked up & went for a drive & the o2 sensors were switching between 14.9 &15.1 to 1. Makes me wonder which one is reading out.
At the end of the day I dont suppose it matters as long as you tune with the one tool. I just wouldnt want to be pushing towards the lean end of the scale.

Always run my PLX. Narrow band simulation on a 40 minute fully warm run: low is .105V, avg .645V and high .980V, the stock narrow band is .080V, .648V and .965V respectivly. Seems like a .003V difference on average.

[Alvin]

I can't see it being the extra load. The PCM is fueling based upon the the load it measures and looks up the appropriate fuel. I'd lean towards the LM-1!:bash:


It was kinda meant to be a joke. We don't have different fuel tables for 1st gear, 2nd gear, etc.

There is something to cycle speed and ignition advance

[Bruce Melton]

Another vote for PLX- not sure how they do it but it no cal, just right on.

[TAQuickness]

The problem with that theory with respect to this is that I had both WB in the same tail tip!

At one point I had the Autronics in the bung after the header collector and the LM-1 in the tail pipe. The Autronics at idle was reporting an idle AFR of 21:1. The motor is bone stock in which we just installed a ProCharger. There was no way it was that lean and idling rock solid at 650!

My point is one; how can you confirm and AFR to calibrate your WB?

Do you disagree that a stone stocker should produced a AFR of 14.7 +/- .1 at idle and that can at least verify that when your WB reports the same that we are at least in the ballpark?

You ever heard of a Hariba (I think its spelled wrong) AFR meter?

It's hard to here sarcasm in text... But you're right - something is bad wrong in the WB calibrations. The only way to confirm your calibration is to test against a known mixture.

[Ira]

If you carefully look at the connector of a 5 wire O2 sensor you'll commonly see 6 or more pins. the extra pin or pins contain a component that the manfacturer selected during test so that fixed calibration electronics have a chance of being close. Calibrating to 20.9 in free air should make for a more accurate system. It is possible to obtain known sample gas to test and calibrate measurement systems but it's neither inexpensive nor easily used. Measuring at the end of the exhaust system gives misleading results whenever the flow is low enough and the time between pulses is long enough that air is drawn back into the pipe.

I believe that a Hariba is a odd 4 wire narrow band sensor that is held to tight enough specifications that it can be used for wider band measurements. A modern 5 wire sensor system should be more accurate over a wider AFR range.

Ira

[VHR]

My car runs best when my Dynojet WB indicates around 11.8. Is that the true a/f ratio? Probably not. The truth to me is the time slip, so I guess I really view it as a tool to compare changes. A rough analogy would be flowing a head on my flow bench and then flowing on another bench. No two benches read the same, so which one gives you the real #?

[Redline Motorsports]

My car runs best when my Dynojet WB indicates around 11.8. Is that the true a/f ratio? Probably not. The truth to me is the time slip, so I guess I really view it as a tool to compare changes. A rough analogy would be flowing a head on my flow bench and then flowing on another bench. No two benches read the same, so which one gives you the real #?

11.8..............I hope its boosted! In my experience there is never really any "big" power in the AFR but its key to providing a mixture that gives the cleanest burn and allows for cylinder cooling.

I disagree about the varience. AFR is AFR. Its a ratio of something and shouldn't vary at specific ratios. Same thing with the flow bench. Dyno's are another story since they conditions are much harder to control.

Bottom line is it would be great to have some kind of test tube device that can produce an engineered AFR to calibrate these units!

Howard

[VHR]

I really dont know what to say, however you should find this discussion illuminating. http://www.tractorsport.com/cgi-bin/forum/cgi-bin/ikonboard.cgi?

[VHR]

I just realized I messed up the link, go to flowbench general and rear the top thread about the plates.

[PladdPezzPunk]

i am curious to see the outcome of this. I know right now I have an LM-1 and it says my truck runs at idle at 14.63:1. I am going to try re-calibrating using the oxygen generator at work. I know that was tested to put out 96%pure oxygen and 4% mixed atmospheric gases. if i fill up a bag straight from the generator, i should have that known mixture. I am going to see if this changes what the sensor say's my truck runs at idle. hopefully i can get some understanding from this. I was always suspect of what was said above. Is my thinking right or way off??