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Misc: Everything Else Air Fuel Gauge 02 Sensor Lambda Sensor


Cyborg

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20 LEDs or 30?
Good catch. I obviously never twigged on that. If you go back to post 2, item H on the list explains it, but its about as clear as mud. Guess I'l find out when I put power to the thing.
There is a 3rd page of the instructions that refers to a button on the back of the gauge used to calibrate and also to return the unit back to the original manufacture settings. With no button visible and not wanting to start blindly stabbing pointy objects into the 4 holes (another under the wide band sticker just in case you're checking my math) I contacted the manufacturer and they told me where it's hiding. Now I need to know... if I'm returning to the manufactures settings, what am I returning from?
A:F Gauge button hole.jpg
 
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Cyborg

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Crap... I'm getting more confused by the minute. So if the wideband sensor produces a voltage based on whatever O2 is left over I would assume it wouldn't matter what fuel was being used if the meter is just taking that voltage signal say 2.34VDC and translating that to 14.7 on the dial. Regardless of fuel, on that dial you would still use 14.7. If you had E85 in the tank, the 14.7 would actually represent 9.7:1 Y/N , but what he is saying is that you just forget about that part and don't subtract anything because of the E85's lower 9.7
 

Cyborg

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In that kickstart/timing thread, Oldhaven asked about this gauge reading in Lamda. After looking at another gauge, I now understand the question (I think).
With the other gauge, you could toggle between AFR and Lambda. I don't know if this one will do that, but I don't think so. I wrote to the manufacturer... again and asked about that along with questions about the infernal button.
 
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Cyborg

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And furthermore...do I need to care about Lambda? Is it just that its easier on the head? As in why would I need to convert the 0-5v signal into lambda. I'm thinking a 0-5V analogue meter. Just mark the dial at 2.34V or whatever it works out to for 1 in lambda or 14.7 in AFR, so like the man said, it's easier to mentally average.
 
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Magnetoman

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If your meter won't display λ you'll still be OK. The number displayed won't be the actual AFR of whatever fuel you use. Instead, it will be the actual λ measured by the sensor multiplied by an arbitrary number (i.e. 14.7). If you mentally divide each reading by 14.7 you'll get λ. But, since the multiplicative factor is a constant, the "AFR" values displayed won't depend on the fuel. So, if you burn pure ethanol, which is stoichiometric with an AFR = 9:1, the meter will display "AFR = 14.7" if the combustion is complete. The displayed numbers are bogus, but you are saved because they are consistently bogus.
 

Cyborg

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If your meter won't display λ you'll still be OK. The number displayed won't be the actual AFR of whatever fuel you use. Instead, it will be the actual λ measured by the sensor multiplied by an arbitrary number (i.e. 14.7). If you mentally divide each reading by 14.7 you'll get λ. But, since the multiplicative factor is a constant, the "AFR" values displayed won't depend on the fuel. So, if you burn pure ethanol, which is stoichiometric with an AFR = 9:1, the meter will display "AFR = 14.7" if the combustion is complete. The displayed numbers are bogus, but you are saved because they are consistently bogus.
Got it...


If I were an experimental physicist who had access to a data logger, I would be tempted to rig up a system to ground out my second spark plug....and switch the spark curve map (which can be done on the fly by switching sensor grounds on the PowerArc ignition) back to a single plug friendly program and see what that does to the voltage coming out of the wideband sensor.
 

Magnetoman

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If I were an experimental physicist who had access to a data logger, I would be tempted to rig up a system to ground out my second spark plug....
If you were an experimental physicist you wouldn't be tempted, you'd be compelled. Going off topic for a moment, when I was in graduate school in Southern California I left the lab late one foggy night and as I left the parking lot on my Triumph it started missing on one cylinder (because of the moisture). I reached down to wiggle the spark plug wire and my memory is still painfully fresh of the feeling caused by three or four pulses of 5000 V going through my elbow grounding out the spark plug.

A mini heat wave has us already at 96 oF at 1pm and headed for a high of 98 oF so I only was able to make one ride today. OK, I could make more, but did I mention it's going to be 98 oF?

A few notes in reading the attached two graphs from my data logger. The values for AFR (magenta), rpm (black), and voltage from the throttle position sensor (red) at the upper right are from the time into the run (11 min. 29.33 sec. for the first graph) where I had the cursor set when I took the screen shot. The rpm values shown in black are 2x what they should be, apparently because the inductive clamp I have laying directly on the magneto is picking up a signal from there as well as the wire. The voltage values are 1.5/5.0 of what they should be because I incorrectly tricked the program when it imported the data -- I should have used a factor of 5.0/1.5.

During the interval between 11:22 and 11:48 on the first graph I had the throttle at a fairly constant ~0.1 so it was mostly running on the pilot circuit. The AFR can be seen to be a very rich 11 or so. The four sharp spikes in this time interval are because the engine missed, allowing raw fuel and oxygen to pass through to the exhaust. Engine rpm was ~7800/2 = 3900 so each combustion cycle was (3900/2)-1 = 0.5 msec. The fact these spikes are seen tells us the response time of the sensor is at least this fast.

The three regions near 11:12, 11:20 and 11:52 show that when I completely rolled off the throttle the exhaust mixture got very lean because only air was passing through under that circumstance.

Turning to the second graph, I had the cursor placed at 8 min. 19.3 sec. for the screen shot, at which point the throttle was wide open. Note that the AFR is a very rich 9.35.

Starting at the far left of this graph it can be seen that in a time of ~1¾ sec. I increased it to ~½ throttle. Up to ~¼ throttle the AFR stayed around 13, but then started dropping as the throttle opened wider, dropping to ~10. I briefly let off the throttle, then rolled it back on to full throttle. Again up to partial throttle the AFR went back to ~13, but again it dropped to below 10 by full throttle. Note that these are "transient" behaviors, not steady state, so there's a lag between changing the throttle position and the engine catching up with the change.

It's not worthwhile analyzing this data any further. The bike was very rich and, as a result, it would load up at low throttle settings and I'd have to rev the engine to clean it out enough that it would again run smoothly. So, there's a lot of bad behavior reflected in various time intervals. Despite this, I thought some of you might like to see examples of what's possible with a data-logging AF sensor. Everything I discussed above went by way too fast to assimilate while on the road dodging cars and with the sun glinting off the display, but afterwards in the air-conditioned light of the living room much was revealed.

This morning I replaced the #30 pilot with a #25 but did not adjust it before today's run for reasons not worth going into. Had I adjusted it I assume the AFR at low throttle settings would have been more reasonable than the super-rich <10 that caused the bike to load up today. I'll drop the main jet by a couple of sizes and adjust the idle mixture before setting off on a similar run tomorrow.
2681726818
 

roy the mechanic

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VOC Member
Despite your best efforts, you must only make ONE change at a time. I ran a rolling road tuning system for 30+ years. If a race winner was not produced within 3 hours I figured I needed a kick in the tender parts. You are in danger of confusing yourselves with too much "data" . It is much harder to sort the wheat from the chaff than stick another jet in and blast down the street. you only have three options-better, worse , or just the same. If its better you are on the case, if its worse, you went the wrong way, if its just the same, check-out the ignition.
 

Magnetoman

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you must only make ONE change at a time. ... in danger of confusing yourselves with too much "data"
"Too much data"? Impossible. That's an alien concept to me...

Actually, I only changed the pilot jet between yesterday and today, and only just now changed the main jet. That's just one change at a time (it's true that before I start out tomorrow I'll tweak the pilot screw, but that only counts as half of a change...).
 

Cyborg

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Your graphs are interesting. Good that you explained the misfire spikes, they would have had me wondering. I wouldn't have thought the response time would be that fast... it really surprises me.

One question.. and maybe its a dumb one, but if the sensor maxes out at 5V, then why does the AFR go over 20?

Speaking of data, although a CX500 Turbo is not likely your cup of tea, I'm guessing a peak inside the ECU would create an endorphin dump.....
 
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Magnetoman

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if the sensor maxes out at 5V, then why does the AFR go over 20?
You're mixing units. The voltage signal from the sensor isn't itself relevant because it's translated by the LM-1 into the AFR number it displays. In principle a sensor that provided an output that went from 0 to 357 Volts, or -27.2 to +45.3 Volts, could be mapped into numbers that ranged from, say, 9 to 20.

I made a bit of progress on my jetting this morning. I found that turning the pilot mixture screw all the way in had no effect on the rpm. The last time I had that problem, coincidentally on a different Gold Star but with a Monobloc, I found the float level was very low. So, although I checked it long ago, it's time to check the float level again. Well, not quite time. We're having a birthday brunch for my older daughter in 45 min. so it will have to wait until later.

With the pilot screw all the way in I made another 8-mile run. Halfway through the run, when the engine was fully up to temperature, I stopped and watched the AFR as I adjusted the pilot screw. It got richer as I backed it out a half turn, and got leaner as I turned it back in, so all the way in was leaner than yesterday (but still not correct). Anyway, with the somewhat leaner pilot mixture the bike behaved better than yesterday. The mixture was still too rich but it never dropped below 10 where igniting it seems to be problematic.

The DocZ rollers are earning their keep. Bikes like rich mixtures to start and my Amal 1036 doesn't have a choke. But, that's no problem with rollers. One problem I am having, though, is I'm way too used to the up-for-down shift pattern of my other Gold Stars. This one has rear sets, but not a reverse cam plate, so it has a Triumph-like up-for-up shift pattern.
 

Cyborg

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Been hiding out in the Channel Islands , so preoccupied with other things for a couple of days... Saw my first giant sea cucumber today.... interesting method of eating those critters have. Helps put dinner at the in-laws into perspective.

Anyway....It was the info that came with the A/F gauge that had me wondering. The voltage maxes out at 5v and the gauge maxes out at 20, so assumed the graph would max out at 20 as well.

How is your jetting session coming along? Btw, I looked up DocZ... I’m envious.

Back to Oldhaven’s question about the gauge displaying lambda. The fellow at the factory got back to me. It turns out that the answer is yes. Apparently underneath the sticker (photo post 41) there are two switches, and you just have to flip switch 2. He did say that the switches are very tiny and easily broken, so he recommended just leaving it as is. They do sell them preset to lambda. Not sure if the switches are any different than normal, or it was just a polite way of telling me that he thinks we’re all lumberjacks here in B.C. and too hamfisted to flip a switch without mangling it...... or he would prefer I bought another gauge. I do have to say, he has been quick to reply and seems genuinely happy to answer questions, so that’s refreshing.
 

Magnetoman

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Been hiding out in the Channel Islands ,
Guernsey and Jersey? Santa Catalina and San Clemente? Newfoundland and Prince Edward?

How is your jetting session coming along? Btw, I looked up DocZ... I’m envious.
The DocZ is a leg saver, if not life saver. There's nothing like it, especially when sorting out jetting.

On the subject of jetting, a few test runs had it behaving like the Monobloc on my Catalina (nb. not Santa Catalina) had, where I found the level in the float bowl very low. So I measured the level and found it very low. Unfortunately, my Concentric box only contains three floats, all of the original 50-year old plastic kind. All are slightly distorted. Although I know how to move the seat to adjust the level that way, instead I decided to order an adjustable 'stay-up' float that's due on Wednesday. Meanwhile, I used the break to get back to the flow bench to characterize the pilot circuit.
 

Cyborg

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VOC Member
At the moment..... 48 degrees 47’59” N 123 degrees 18’37” W in the Salish Sea
about to top off some leftover turkey with a wee dram of scotch.

May sound glamorous, but if you saw what I’m floating on, you’d know why I’m consuming alcohol.

“Channel Islands” would be misleading I suppose. They are actually referred to as the gulf islands, but are in the Straight of Georgia that is called the Salish Sea by BC’s indigenous folk. What do I know.. I’m a former flatlander and it looks more like a channel to me.
 
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JustPlainBill0

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Non-VOC Member
I'm not sure this will be of any value to this discussion, but I replaced my Rapide's Amal carbs with Taiwan versions of Keihin PWK 30mm carbs and have been using an AEM AFR meter to adjust the carbs - at least idle and up to quarter throttle. (My Rapide is not roadworthy now and further tuning will have to wait until it is.)

What might be helpful in a general (practical?) sense, is a video I made of the tools, set up, equipment and procedure I'm using in this endeavor:


I'm using two cameras in the video, one to record my activities and one to record the AFR meter and tachometer. The second camera serves as my data logger; and should be especially helpful when I do get the Rapide on the road.

There is very little technical information in the video, but the last two minutes consists of a demonstration of synchronizing the carbs and adjusting the pilot circuit - with the AFR meter video inset into the main picture to allow viewers to watch the AFR reading changing as the adjustments are made.

Bill
 

Cyborg

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Welcome to the forum and welcome to this thread.

As mentioned previously in this thread, my instructions also say to mount the bung at least 18" from the port, but it goes on to say "if you expect EGT over 800 C". I'm still thinking that less than 18 is ok if Ducati can do it. Farther from the tail pipe would be good in my case because I'm using a relatively short reverse cone setup.

Can't say I'm in the mood to buy another (EGT) gauge after my recent fiasco with "Smiths" or should I say "the Smiths"..as in plural.
 

JustPlainBill0

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Non-VOC Member
Thanks for the welcome Cyborg. This has been a very informative and entertaining thread, but after having watched a video today titled "Do You Want A Lean OR Rich AFR? | Fueling VS Power! [FREE LESSON]" by a New Zealand outfit called High Performance Academy, I'm afraid the thread might fall into the category of over thinking the problem. The presenter (Andre) starts off making the point that while a 14.7 AFR (stochiometric) might be ideal for power and fuel economy, a richer fuel mixture provides more fuel to mix with the air, helps burn all the oxygen and therefore, obtain all the power possible from the engine. Furthermore, it aids cylinder cooling and ultimately prolongs engine life. His next point, and what the remaining 13 minutes of the video demonstrates using a dynomometer, is that fairly significant changes in AFR (or Lambda) do not make correspondingly significant changes in power from the engine. I do not use Lambda, but I do understand that when one varies the AFR by about 10% (from Lambda 0.87 to 0.97) and the torque curve is basically unchanged (with otherwise identical conditions), there might be more value in getting our AFR values to the "good enough for government work" stage, than obsessing over the process. Though Andre's conclusion that running a richer fuel mix to get the same power is better for the reasons listed above, is a good one too.

I have been using the AFR recommendations I found on this Harley site: http://www.nightrider.com/biketech/Pro_tuning.htm to tune my Rapide.

Operating Mode
Cold Start
Idle
Part Throttle Cruise
Wide Open Throttle
Performance Engine
12.5 -11.5
During engine warm up
13.5 - 12.8
14.0 - 13.0
12.8 - 12.5
Values as rich as 11.5 can be used to reduce detonation
Pollution Controlled Vehicles
12.5
14.6
14.6
13.8 - 12.5


Oh yeah, a link to the HP Academy video:


Bill
 

Cyborg

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I haven't viewed the video yet, just taking a break from putting the roof on the apprentices playhouse. I haven't used an AF gauge before, but don't think my expectations are unrealistic. Just expecting it to tell me whats going on and final settings will be based on drivability not the gauge... and maybe a peek at the plug because the fuel we get here is still relatively normal. To me its just another tool and don't see myself chasing a specific number. Actually for street riding, I look at a dyno the same way. It can tell the operator some extremely useful information, but how the bike behaves on a dyno may or may not tell you how it is going to operate in the real world and may still require some tweaking. Later this month I'm scheduled to do some farting around with A/F sensors and data acquisition/logging, so that may alter my expectations slightly. They have a dyno there, but unfortunately it's not really motorcycle friendly.


EDIT: watched the video and didn't see anything that would cause me to change my point of view or see any surprises unless I'm missing something. Slightly different ball game with programable ECUs, modern combustion chambers and fuel injection. As for over thinking the problem, I suppose that depends on your perspective and you certainly wouldn't be alone in that camp. There is no doubt one can jet a carburetor without any fancy gismos, but no regrets so far as I'm having fun learning.
 
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Magnetoman

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Slightly different ball game with programable ECUs, modern combustion chambers and fuel injection.
I'm afraid the thread might fall into the category of over thinking the problem.
It might count as overthinking the problem if our bikes had fuel injection and programmable ECUs where we could input our desired AFR and let the ECU take care of giving that to us to within 0.1 at all rpm. Unfortunately, we have Amal carburetors where we have to manually adjust the pilot mixture screw, slide cutaway, needle jet, needle notch, and main jet to give AFRs approximating what we want across all throttle settings. So, no, this thread isn't overthinking the problem.
 

Cyborg

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Correction..... you have an Amal.... I have a Mikuni Flat Slide

We need an emoji with a smug look on his face and an aura of superiority.

(I have a feeling that will come back to haunt me)
 

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