Thanks for the peace of mind, Charlie - that's good to know. What temperature should I start to get worried, or at least pull over and let it cool down?

Probably something like 240-250*F. The factory dash light comes on at 140*C/284*F for reference.

Generally though, you should try to keep it under 200*F for most operating conditions (cruising down the freeway, etc.), which is why many install a secondary cooler.

-Charlie

Thanks charlie now know where to hook in my aftermarket transmission gauge to
get the highest temp reading...

Cooler line outlet.

Luckers is correct. Weird how your scanner did that. Your downstream is monitoring two cats, which is retarded. If one goes bad you don't know which one. According to that almost too perfect to be true signal both cats are good. I would double check those values at the PCM or backprobe at the sensors to be sure. My heart would sink and I would punch myself in the mouth if my transmission fluid was dark and burnt. I like bright pink and clean magnets. The fluid doesn't work in that condition. Hopefully you haven't done damage.. Personally I do a full flush every ten thousand miles. And the filter needs changed everytime too. 75% of my mileage is trail, never had hot fluid.

Please avoid quoting me in the future. Thank you.

Sorry, didn’t get notification of any replies in this thread.

This isn’t right. He has a front AFR sensor, which is not a narrowband O2 sensor that you’re describing. The AFR sensor is essentially a wideband O2 sensor. So as long as the AFR is constant, the output voltage reported by the ECU for bank 1 sensor 1 will also hold constant.

@prybar you need to rescale the graph so that minimum value is 0.40v and max is 0.80v. Stoich (14.7 for pure gas) will return a voltage value of 0.66v. If you know how to setup custom PIDs in that app, you can actually program it to interpolate voltage into actual AFR value, or lambda value if you prefer that instead.

Attached Images

 

It's not a wideband sensor. Voltage will fluctuate for the upstream sensor as it changes and adjusts fuel trims. Feel free to provide a source for where it says that it's a wideband sensor though.

Dual cats = front sensor is wideband (well, not quite - it is an AFR sensor with a reduced range compared to true wideband sensors). They are on '99-'00 California emissions and all '01-'02 4Runners. The output of that sensor is scaled to narroband-style readings for reporting via OBD-II, but can be converted back to wideband with the chart above.

All '96-'98 and Federal Emissions '99-'00 had a normal front O2 sensor that will have the widely varying output voltage.

Check the FSM, wiring diagrams, etc. It is all spelled out there.

-Charlie

Toyota's Air Fuel Ratio sensor is absolutely a wideband O2 sensor. This is common knowledge on this board, or at least it was 10 years ago. Perhaps with a lot of the knowledge base moving on to newer vehicles, this has been forgotten. This is easily Google-able. In the earlier 3rd gens ('96-'98), the front O2 sensor was the traditional narrowband type O2 sensor. The 3rd gens that use the narrowband front O2 sensor can be readily identified by the fact that they have one (1) OEM catalytic converter. The B1S1 O2 readings on those sensors will oscillate between "high" and "low" and the narrowband O2 sensor does not have the ability to tell exactly what the air-fuel ratio is; only that is either rich or lean.

I believe it was in '99 (going from memory here) that the 3rd gens came with either the Federal Emissions or the California Emissions. Again, Federal Emissions used the traditional narrowband O2 sensor that should oscillate. The California Emissions used Toyota's "Air Fuel Ratio Sensor" that is essentially a wideband O2 sensor. The AFR sensor, unlike the traditional O2 sensor, can detect exactly what the air fuel ratio is at any given moment. The California Emissions vehicles can be identified by the fact they have two (2) OEM catalytic converters. The B1S1 O2 readings will be much more steady, and not bounce around like the older style narrowband O2 sensors. Instead, the reported voltage will correspond to the air-fuel ratio that I posted in the chart above.

At some point, I think it was either 2000 or 2001, all 3rd gens came with Air Fuel Ratio sensors, regardless of being Federal or California Emissions. Again, the fact that these 4Runners had two OEM catalytic converters readily identified them as having the Air Fuel Ratio sensors. Basically any 3rd gen that came from the factory with two catalytic converters has the Air Fuel Ratio sensor up front.

If it came from the factory with one OEM catalytic converter, then it has the older style narrowband O2 sensor up front. If it came from the factory with two, then it has the Air Fuel Ratio sensor up front.

In short, his scan tool did not switch the voltages between B1S1 and B1S2 O2 sensors. His scan tool is reading about what would be expected.

Still waiting on any sort of evidence to prove that it's a wideband. As far as I've seen and experienced it's just a normal range air/fuel sensor (for California emissions) or a normal oxygen sensor for everything else.

There's a difference in sensing range between a wide band air/fuel sensor and the air/fuel sensor that Toyota uses. If you aren't going to provide any sources to back up your statements then I'll see my way out.

Wow, way to be pedantic. It is a 'wide-band' in the sense that it is not a traditional O2 sensor. You guys are saying the same thing. Ok, so it doesn't sense 9:1 up to 20:1, it only is accurate from around 12:1 up to 18:1. The point is that it can accurately sense more than about 14.6:1 to 14.8:1.

-Charlie

When presented with a conflicting point of view/idea from what I've established through my own experience, research, and knowledge to be true then I require substantiated evidence to change that. A lengthy explanation of what someone thinks is great, but not really a verified source. Maybe if more people adopted this outlook there would be fewer people believing the moon landing was fake, the earth is flat, and aliens walk among us. Am I being difficult? Absolutely! If the roles were reversed I would provide outside evidence as well if someone required it. Should be pretty easy for him to provide it since it's "easily Google-able".

EDIT: Yes, I know I'm a dick/*******/etc.

LOL are you serious? So now you're acknowledging that it's an AFR sensor (and can report the actual air fuel ratio, unlike an older style O2 sensor)...

...which contradicts your prior post where you describe the operation of a traditional narrowband O2 sensor (and not an air/fuel sensor)...

So let me ask you this. Do you still stand by your statement that you think OP's scan tool is switching readings between sensor 1 and 2?

@Bad Luck , here you go. Here is some reading material for you:

https://www.autoequipment.com.au/ima...20Part%203.pdf

Wideband O2 Sensors and Air/Fuel (A/F) Sensors