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.
26817
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roy the mechanic

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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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