Wideband O2 Sensor

[TomoHawk]

The best sensor to use would be the wide-band (4-wire) ones, but I think those have heating elements in them, which requires something more than just connecting the wire to the battery.  Is there any idea what could be used?

Edited December 4, 2016 by TomoHawk

[sweatybetty]

i am planning on using one of these http://www.jegs.com/i/FAST/244/170402/10002/-1  1 sensor for the front 3 and 1 for the rear 3 cylinders. it should make tuning easy. if you wanted really simple  http://www.jegs.com/i/Innovate-Motorsports/540/3844/10002/-1

[TomoHawk]

I like the old-fashioned way of tinkering with the Zed, just like my home-made PWM light dimmer, so I'll keep working with the DIY stuff, unless you'd like to buy one or me

[TomoHawk]

Actually, there is no such thing as an air-to-fuel sensor!  People are fooled into thinking that the OXYGEN sensor can measure air and fuel??

The oxygen sensor's purpose is to detect oxygen- a little or a lot, and gives a corresponding signal of some form- volts or current.

To know the air-to-fuel ratio, you need to know the amount of fuel, and the amount of air, obviously.  Electronic fuel injection can do that, using the intake sensors- MAF or AFM, air temperature, etc., then by measuring the pressure in the fuel lines  it can "calculate" how much fuel to inject.  The oxygen sensor's job is to give feedback to the computer/controller, and if it detects lots of oxygen, it means there probably wasn't enough fuel injected, and vice-versa. 

That only works assuming you have an engine that is working perfectly for the E.F.I to get things right for a 100% complete burn.  If not, the controller thinks it's running rich or lean and tries to adjust, or eventually  gives "errors" or the "check engine" light is illuminated.

Therefore...  the oxygen sensor is NOT an air-to-fuel ratio sensor.  There is no such thing.  It takes a number of sensors and some electronic calculating to get the the air-fuel mix to what it should be, and on the newer E.F.I. systems, you can fool with that too.

The best people (with L-Jet E.F.I.) can do is to make a lot of assumptions, like the spark is good, the spark timing of right for the revs, and then adjust the AFM (tighten or loosen the spring) to get the ECU to add more or less fuel to the cylinders.  People who incorrectly think the oxygen sensor can determine the air-fuel directly are making a LOT of assumptions and  are not achieving the goal of a correct fuel mixture.

So using ANY oxygen sensor in the exhaust stream to predict the air-to-fuel mixture going into the cylinders is like measuring the fuel level in the fuel tank by putting the oxygen sensor in the filler neck.

 

Edited December 28, 2016 by TomoHawk

[Zed Head]

You raise a good point.  I realized that I don't really understand how the sensors/gauges work either (can't say that I do now either).  Innovate has  a paper that does a good job of explaining it.  Excess fuel left over after all of the oxygen has burned apparently also cause a voltage in the sensor.  The voltage is then used in a calculation to give the ratio.  Pretty interesting and more complex than I had thought.  It's the "pump" that makes the difference I think.

http://www.innovatemotorsports.com/resources/news3.php

Here's another.

http://tayloredge.com/reference/Science/oxygensensor3.pdf

One more.

http://www.megamanual.com/PWC/LSU4.htm

[TomoHawk]

The only thing it does is detect oxygen- that's why it's called an oxygen sensor.  It doesn't detect fuel at all.  Neither is it an indication or guarantee that ALL the oxygen in that went into the cylinder was used up. If you disconnected the spark plug(s) it would detect a LOT of oxygen that passed through the cylinder, unburned, as well as a lot of fuel, and would probably give you a lean "reading."  That's if it didn't get fouled by the fuel.

[Zed Head]

Problems like these are why we have hobbies like Z cars in the first place.  Worlds colliding here...

[TomoHawk]

I'm focusing on the narrow-band sensors. 

It still doesn't tell you the air-to-to fuel mixture of what is going into the cylinders.  It tells you how much stuff  there is in the exhaust that can be oxidized.  Don't forget that only certain sensors have the Nuernst pump or the heater.

Most people in those Youtube videos are using the narrow-band sensors and claiming they have an air-fuel-ratio meter.

Edited December 28, 2016 by TomoHawk

[Zed Head]

4 minutes ago, TomoHawk said:

I'm focusing on the narrow-band sensors. 

It still doesn't tell you the air-to-to fuel mixture of what is going into the cylinders.  It tells you how much stuff  there is in the exhaust that can be oxidized.

The title of your thread is Wideband O2 Sensor.  I missed the changeover point.

I think that you're oversimpifying.  It's a complex device.

 

[Zed Head]

No offense intended on the "simpify" misspelling.  I left it because it seemed funny.  Oversimpify should be an actual word, I think.

[TomoHawk]

I changed my interest to the narrow-band sensors because you can just put one into the exhaust stream and get some kind of signal.  For the wide-band sensors, which supposedly give you an actual air-fuel ratio, you need complex control  circuits for the heater and to interpret the signal from the sensor.  Even though the result is somewhat misleading, the display circuit for the narrow band sensor is simple and I should be able to make a PC board in a day or two- if I get motivated! It might be fun to play with.

I have a bluetooth OBD adapter and I viewed the signals from the two oxygen sensors on the exhaust, and with the combined signals, you can get a bit of an understanding of what  the ECU is doing with the fuel mixture.  I also had a go with a "dyno" application, and the results were kinda funny.

Edited December 28, 2016 by TomoHawk

[conedodger]

Here is my setup. I hid the gauge in the ashtray which I don't use. I welded a bung in the header after the six pipes collect. Originality or the appearance of originality is a guiding principle to me. This allowed me to tune the carbs as best as carbs can ever be tuned I guess. Then, when I'm done gathering my information, I close the ashtray cover and it's gone!