The stock o2 sensor is a wideband

[The Spectacle]

I figure this is the best place to put this info. I won an aftermarket wideband in a contest and said screw it and installed it on the Yaris for s & g's. Few observations of note:

- 14.5-14.7 AFR is the cruising and idle target
- The o2 readings DO NOT oscillate during cruise. They reach the target and move .1-.2 points one way or the other to maintain the target. Narrowband sensors do not do this
- From what I can tell, the computer adjusts very fast and very accurately. Was very surprised to see this behavior
- Open loop WOT with the stock intake drops the AFR to 12.5 (rich). After installing my Injen CAI, the target raised to 13.1. Stock airbox is a major restriction on this car. Very noticeable difference between the two
- AFR richens up to a mind boggling 10.9 with the stock airbox right before and up to redline. With the intake its like 11.3 or so (I can't exactly remember, only did it once or twice)

From what I can tell, with just a proper standalone/piggyback computer this motor could easily pull 115-120whp with tuning and regular I/H/E upgrades.

[auxmike]

Did you use Scangage II?

[YarisSedan]

That could be because the yaris utilizes air fuel ratio sensors which is wide range. More expensive and more acurate. Where as oxygen sensor is more narrow range. The one after the cat is probally regular o2 sensor.

[fnkngrv]

We noticed this when I was attempting my first few tries at calibrating my FIC

[The Spectacle]

Did you use Scangage II?

For monitoring all the stock sensors and gas mileage, yes. To monitor the wideband, I have a gauge

http://a6.sphotos.ak.fbcdn.net/hphotos-ak-ash4/253778_171993546195658_100001550411012_413206_4310 699_n.jpg?dl=1, http://www.facebook.com/photo.php?fbid=171993546195658&set=a.124601237601556.18375.100001550411012&type=1&theater

That could be because the yaris utilizes air fuel ratio sensors which is wide range. More expensive and more acurate. Where as oxygen sensor is more narrow range. The one after the cat is probally regular o2 sensor.

Agreed. Primary o2 is wideband, secondary is narrow

[Bluevitz-rs]

Primary is not an O2 sensor, it's a A/F ratio sensor. But the secondary is an O2.

[The Spectacle]

Primary is not an O2 sensor, it's a A/F ratio sensor. But the secondary is an O2.

Edit: My Echo has 2 O2 sensors. That's what makes the Echo/Xb/Xa easier to tune. The computer is dumber than the Yaris.

What are you talking about? That makes absolutely no sense whatsoever.

[thepartsmancometh]

almost all newer toyota's use A/F sensors in the front position(2) and O2 after cat. The A/F's aren't exactly cheap, but they have their benefits.

[Bluevitz-rs]

I re-edited my post to be less confusing for you.

[mazilla]

Just to clear something up for myself...if the primary is A/F, why am I looking for a gauge with it's own sensor? Can I just run a gauge only and be done with that?

This is in regards to my turbo install coming up, gauges are all I need at this point.

[Bluevitz-rs]

from the original post that looks to be all that's needed.

[The Spectacle]

I re-edited my post to be less confusing for you.

Still confusing as all hell but I think I understand what you're trying to say. Both sensors are o2 sensors but only one has a range wide enough to read A/F, while the other can only read rich or lean. Most aftermarket wideband o2's are 0-5 volts and stock narrowbands 02's are 0-1 volts.

Just to clear something up for myself...if the primary is A/F, why am I looking for a gauge with it's own sensor? Can I just run a gauge only and be done with that?

This is in regards to my turbo install coming up, gauges are all I need at this point.

I wouldn't mess with the stock o2. Who knows what the voltage ranges for that sensor are and how the ECU reads them. Your best bet is going the route I did, unless you can find a OBD2 reader than can pull A/F from the OB2 port.

I got my gauge from Prosport http://prosportgauges.com/

[The Spectacle]

To be 100% clear...I am not pulling my readings from the stock o2 sensor itself. My gauge is reading from an independent sensor that's installed near the stock o2 port on the header.

[Bluevitz-rs]

ok, I'll dumb it down as much as I can.

The first sensor in the exhaust located in the manifold is called an AIR/FUEL RATIO SENSOR. NOT AND OXYGEN SENSOR. The second sensor in the exhaust located after the catalytic converter IS call an Oxygen Sensor.

The job of the A/F Ratio Sensor is to adjust fuel delivery to maintain set parameters from the ECU. This a very fast and sensitive sensor.

The job of the Oxygen Sensor is to make sure the Catalytic Converter is doing it's job. This is a slow acting narrow range sensor.

The Yaris has a more sophisticated ECU compared to the Echo and can more accurately control fuel delivery based on more accurate readings from the AFR sensor.

[ilikerice]

Bluevitz is absolutely correct.

pre-cat is an Air/Fuel sensor. post-cat is the Oxygen sensor.

[cali yaris]

^ The first one is actually a hybrid design, but that's getting pretty nitpicky.

[The Spectacle]

No he's not. A/F sensors ARE o2 sensors! What the hell do you think the sensor is reading? Magic fairy dust?

You're arguing semantics with me and its making my head hurt.

[ilikerice]

Ok, I will agree there. Most people do refer to those sensors as O2. I was trained by toyota that they are a/f sensors. Which you are correct, is just a wideband O2 sensor.

So to get this thread back on topic. YES, toyota has been using a wideband O2 sensor for the past 15 years.

[CTScott]

ilikerice sent me a PM with a question about connecting a gauge to the OEM primary sensor, so I figured I'd answer it in here instead of by PM.

The stock AFR sensor is a typical heated platinum coated zirconia A/F sensor. These sensors require a considerable amount of work by the device monitoring them. The heater within the sensor is used to increase its sensitivity when the exhaust gas is cold, but if it gets too hot it also has accuracy issues, so the monitoring device must constantly adjust the duty cycle of the heater. It also maintains a constant voltage across the A1A+ to A1A- terminals of the sensor. It measures the current draw, rather than voltage change of the sensor, so if your were to measure the voltage on the A1A+ or A1A- pins of the sensor, they would remain constant. So, since reading the sensor requires closed loop control, it would be almost impossible to run two gauges on one sensor.

Using the Toyota diagnostics messaging (a step above simple OBDII) that I reverse engineered from the TechStream tool, I read and display the realtime AFR on my YarGauge.

Some vehicles support an OBDII PID for AFR (which allows displaying it as a X-gauge on the scangauge), but due to the communication frequency limitations of OBDII this tends lag significantly, making it not very useful.

[mazilla]

ilikerice sent me a PM with a question about connecting a gauge to the OEM primary sensor, so I figured I'd answer it in here instead of by PM.

The stock AFR sensor is a typical heated platinum coated zirconia A/F sensor. These sensors require a considerable amount of work by the device monitoring them. The heater within the sensor is used to increase its sensitivity when the exhaust gas is cold, but if it gets too hot it also has accuracy issues, so the monitoring device must constantly adjust the duty cycle of the heater. It also maintains a constant voltage across the A1A+ to A1A- terminals of the sensor. It measures the current draw, rather than voltage change of the sensor, so if your were to measure the voltage on the A1A+ or A1A- pins of the sensor, they would remain constant. So, since reading the sensor requires closed loop control, it would be almost impossible to run two gauges on one sensor.

Using the Toyota diagnostics messaging (a step above simple OBDII) that I reverse engineered from the TechStream tool, I read and display the realtime AFR on my YarGauge.

Some vehicles support an OBDII PID for AFR (which allows displaying it as a X-gauge on the scangauge), but due to the communication frequency limitations of OBDII this tends lag significantly, making it not very useful.

Time to bump the YarGauge thread!! :tongue::tongue:



I don't wanna spend 250.00+ on my AFR gauge.:cry: :help:

[eTiMaGo]

ilikerice sent me a PM with a question about connecting a gauge to the OEM primary sensor, so I figured I'd answer it in here instead of by PM.

The stock AFR sensor is a typical heated platinum coated zirconia A/F sensor. These sensors require a considerable amount of work by the device monitoring them. The heater within the sensor is used to increase its sensitivity when the exhaust gas is cold, but if it gets too hot it also has accuracy issues, so the monitoring device must constantly adjust the duty cycle of the heater. It also maintains a constant voltage across the A1A+ to A1A- terminals of the sensor. It measures the current draw, rather than voltage change of the sensor, so if your were to measure the voltage on the A1A+ or A1A- pins of the sensor, they would remain constant. So, since reading the sensor requires closed loop control, it would be almost impossible to run two gauges on one sensor.

Using the Toyota diagnostics messaging (a step above simple OBDII) that I reverse engineered from the TechStream tool, I read and display the realtime AFR on my YarGauge.

Some vehicles support an OBDII PID for AFR (which allows displaying it as a X-gauge on the scangauge), but due to the communication frequency limitations of OBDII this tends lag significantly, making it not very useful.

Scott, do you remember which code it is for the X-gauge? I tried a few and the only one that worked seemed to give me more of a "target" AFR (IE it stayed at 14.6 driving normally and somewhat richer under heavier (but still closed-loop) acceleration

[CTScott]

Scott, do you remember which code it is for the X-gauge? I tried a few and the only one that worked seemed to give me more of a "target" AFR (IE it stayed at 14.6 driving normally and somewhat richer under heavier (but still closed-loop) acceleration

I don't recall, but I don't believe that Toyota vehicles support the ODBII AFR PID. I think you can only get at the "target" one from ODBII, which is absolutely worthless.

[eTiMaGo]

ok gotcha thanks