narrow-band A/F gauge is reading VERY lean after a series of mods/engine-bay cleaning
03-27-06, 12:09 AM
#27
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Eye on Electronics, by Mike Dale:
"...As you know, conventional O2 sensors are characterized by a rather sudden shift between a high and low output that occurs very near the ideal air/fuel mix known as stoichiometry (14.7 to 1). How much richer or leaner the mixure is doesn't really affect the output of the sensor once it has started switching. On the lean side, it's typical output is .1 volt, whether the air/fuel mix is 15 to 1 or 19 to 1. On the rich side, the output is about 1 volt from a 14-to-1 ratio on down to richer mixures. In the world of electronics, this in known as a step funchtion type of sensor..."
Here is a narrow band graph that I made in paint. The manufacturing tolerances of the graph do not reflect the actual numbers output from a narrowband O2 sensor, but merly an Idea of what it looks like:
For comparison, this is what the graph of a Wideband looks like, taken directly from "Eye on Electronics":
Note the differences between the areas right around Stoich. It is true, like RETed said: "There is a very narrow voltage range which the sensor is very linear.
Outside of that range, it's basically binary." --Speaking of the Narrowband.
I don't see why you would disagree with my initial statement.
It seems that there is an overwhelming cling to technicality on this forum. Please, let the referenced technical documents do the talking, and let's stop picking apart the grammar of each statement to make ourselves feel smarter.
It seems that I am the only person on this forum who CAN actually back up claims that they make. Not with more opinions, but with an article, picture, graph, etc.
"...As you know, conventional O2 sensors are characterized by a rather sudden shift between a high and low output that occurs very near the ideal air/fuel mix known as stoichiometry (14.7 to 1). How much richer or leaner the mixure is doesn't really affect the output of the sensor once it has started switching. On the lean side, it's typical output is .1 volt, whether the air/fuel mix is 15 to 1 or 19 to 1. On the rich side, the output is about 1 volt from a 14-to-1 ratio on down to richer mixures. In the world of electronics, this in known as a step funchtion type of sensor..."
Here is a narrow band graph that I made in paint. The manufacturing tolerances of the graph do not reflect the actual numbers output from a narrowband O2 sensor, but merly an Idea of what it looks like:
For comparison, this is what the graph of a Wideband looks like, taken directly from "Eye on Electronics":
Note the differences between the areas right around Stoich. It is true, like RETed said: "There is a very narrow voltage range which the sensor is very linear.
Outside of that range, it's basically binary." --Speaking of the Narrowband.
I don't see why you would disagree with my initial statement.
It seems that there is an overwhelming cling to technicality on this forum. Please, let the referenced technical documents do the talking, and let's stop picking apart the grammar of each statement to make ourselves feel smarter.
It seems that I am the only person on this forum who CAN actually back up claims that they make. Not with more opinions, but with an article, picture, graph, etc.
Last edited by Needa13b; 03-27-06 at 12:13 AM.
03-27-06, 12:11 AM
#28
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Originally Posted by eriksseven
Hmm... From my experience, it's decent for telling me what's going on. You can debate all you want, but honestly? When the engine hiccups, the gauge goes red (lean), when I roll into the throttle, the gauge goes from the stoich position and makes it's way into the rich. At WOT it goes rich. At idle it's a (wavering) stoich. It's not just "red and green", you can actually watch and *feel* the changes that the gauge reads.
To defend myself, I did not make the statement to tell you that you could not notice trends of engine behavior vs. Rich/Lean/Stoich observations. But your guage will not tell you that you are 15:1 or 19:1, you are just plain Lean.
And the wavering you speak of is going from rich to lean to rich to lean. (sounds very binary to me). When you stomp on the throttle, the needle may go farther rich, but as you can see from the graph, it's hard to get an accurate degree of your A/F ratio.
Last edited by Needa13b; 03-27-06 at 12:19 AM.
03-27-06, 12:22 AM
#29
Originally Posted by Needa13b
To defend myself, I did not make the statement to tell you that you could not notice trends of engine behavior vs. Rich/Lean/Stoich observations. But your guage will not tell you that you are 15:1 or 19:1, you are just plain Lean.
BTW, you're not the only one who can back up claims on this forum... Some people typically don't have to (because of their experience, they're trustworthy), others don't care to (because they're confident that it can be backed up), and some do via pics, graphs, written data etc... You just went the extra mile.
03-27-06, 12:31 AM
#30
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Originally Posted by eriksseven
Of course not... I would be stupid to claim that it could, therefore I didn't make those claims.
BTW, you're not the only one who can back up claims on this forum... Some people typically don't have to (because of their experience, they're trustworthy), others don't care to (because they're confident that it can be backed up), and some do via pics, graphs, written data etc... You just went the extra mile.
BTW, you're not the only one who can back up claims on this forum... Some people typically don't have to (because of their experience, they're trustworthy), others don't care to (because they're confident that it can be backed up), and some do via pics, graphs, written data etc... You just went the extra mile.
This forum is for information, and people on here do post links and pictures and graphs, but I said it SEEMS that most people don't. They just post a claim, or worse, they post that something posted was wrong, just because...
If there is to be any debate, it should be made by the articles that tell the facts, not the people who interpret them in their own way.
03-27-06, 12:39 AM
#31
this is a technical forum so technical data is used for reference, sure it was a harsh way to put it but it is still a fact that it is not an on/off switch type of sensor rather than a narrow voltage analog that the computer basically interperets as a on/off signal while switchng rapidly it is stoich but some sensors are more accurate than others as well mileage can affect the sensors reliability.
the narrowband is still a useless tool to use in tuning a boosted or even any engine, it is used for cruising under a light load. most any engine under hard loads wt a stoich point will be detonating or close to it, in a boosted rotary this means death to the motor so once the narrowband gauge starts reading lean you have a split second to lay off or kiss it goodbye, usually it's too late already.
the narrowband is still a useless tool to use in tuning a boosted or even any engine, it is used for cruising under a light load. most any engine under hard loads wt a stoich point will be detonating or close to it, in a boosted rotary this means death to the motor so once the narrowband gauge starts reading lean you have a split second to lay off or kiss it goodbye, usually it's too late already.
03-27-06, 01:38 AM
#33
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Originally Posted by Karack
the narrowband is still a useless tool to use in tuning a boosted or even any engine, it is used for cruising under a light load. most any engine under hard loads wt a stoich point will be detonating or close to it, in a boosted rotary this means death to the motor so once the narrowband gauge starts reading lean you have a split second to lay off or kiss it goodbye, usually it's too late already.
This does not make it "useless".
Almost everyone has a narrow-band O2 sensor - stock - so why not use it?
The wide-band system is a totally new purchase that's going to cost you several hundred dollars - an AFR gauge + EGT gauge is typically cheaper.
The wide-band can't help you jack **** with tuning ignition timing; that makes it USELESS when trying to tune ignition timing.
I'll let you figure out why I use the combo to tune.
-Ted
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