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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Air Fuel Ratio

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Author Topic: Air Fuel Ratio
steeleshark2
Member
Posts: 22
Post Re: Air Fuel Ratio
on: October 6, 2011 (GMT)

I will definetley send a debug. I wonder if the other person has a tune which disabled them? I just remember looking at the pids and see voltages on the o2 sensors. The AFR however is not greeen. I will try to get it to you today. Thanks again!!

piemmm
Administrator
Posts: 6069
Post Re: Air Fuel Ratio
on: October 6, 2011 (GMT)

Hi

Actually you have a good point, though I would expect the tune to disable access to the commanded AFR (as you could use it as a (very) crude way to read the vehicle mapping :-)

I’ll look forward to the debug, make sure the ‘description’ is something I’ll recognise, only has to be short

steeleshark2
Member
Posts: 22
Post Re: Air Fuel Ratio
on: October 6, 2011 (GMT)

Debug sent!!

piemmm
Administrator
Posts: 6069
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

Hm,

Same thing – the O2 equiv sensors aren’t visible on the standard OBD2 block for your vehicle (though the voltages are, but normally, they’re not much use).

The O2 voltages – when you vehicle is warmed up, after a couple of minutes, do they oscillate (up/down) all the time, or (at idle) are they a flat(ish) line? – I’m particularly interested in O2S1 voltage.

steeleshark2
Member
Posts: 22
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

That was warmed up. I do have a cam in the car so I do not know if others o2 sensors would be the same way. So, now I need to see if I can find new Equiv Pids for the o2 sensors.

nextnme
Member
Posts: 9
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

This link was helpful: http://forums.rennlist.com/rennforums/944-turbo-and-turbo-s-forum/603073-o2-sensor-voltage-range-to-afrs.html

Pretty much says “2.5 x Volt + 10 = AFR” based on a 0v – 4v O2 sensor.

If ours is a 0v – 1v system (narrowband) then the equation would be “10 x Volt + 10 = AFR”

piemmm
Administrator
Posts: 6069
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

Yes, but unfortunately the voltage coming out of the O2 sensor is a sine wave, it’s not constant. (You’ll see this if you add the O2 voltage display in Torque) which you would need continuous monitoring (and *fast* monitoring) of that PID to determine the current AFR.

To do this accurately would mean that you would need to get at least 15+PIDs/sec just for monitoring a single O2 sensor, which rules out using it.

This page explains this in a better way:

http://www.picoauto.com/applications/lambda-sensor.html

At the moment, I need someone with a camaro to confirm to me that O2S1 voltage is fluctuating like this, or is relatively ‘flat’

nextnme
Member
Posts: 9
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

“O2 Volts Bank 1 sensor 1” fluctuates from .1 to .8, with a gage range of 0 – 1.

“O2 Volts Bank 1 sensor 2” remains relatively stable at .79 – .81, with a gage range of 0 – 1.

“O2 Volts Bank 1 sensor 3, and 4” have no data

“O2 Volts Bank 2 sensor 1” fluctuates from .1 to .8, with a gage range of 0 – 1.

“O2 Volts Bank 2 sensor 2” remains relatively stable at .79 – .81, with a gage range of 0 – 1.

“O2 Volts Bank 2 sensor 3, and 4” have no data

piemmm
Administrator
Posts: 6069
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

Thats good. – you have ‘normal’ O2 sensors before and after the catalytic converter.

The sensors that aren’t changing much are located after the catalytic converter, compared to the one before the cat, and the big difference between both sensors is good, as it means your cat is working properly. Systems with broken (or missing) catalytic converters with have both those sensors oscillating in the same range.

Unfortunately it doesn’t help us much with AFR though – it’s almost impossible to get the average of that sine without dedicating the adapter to only reading one of those sensors (it’s far more efficient to let the ECU do that work and present it as a PID).

It may be possible to write a plugin dedicated to only retrieving that reading, but it wouldn’t be able to retrieve any other sensor information whilst doing it (as it would need all the available bandwidth to sample the O2 as often as possible. This might be what the other scantools are doing (if they aren’t doing it the easy way and using some (currently unknown) manufacturer specific extended PID to get that information)

nextnme
Member
Posts: 9
Post Re: Air Fuel Ratio
on: October 7, 2011 (GMT)

Well I’ll be hornswoggled!

I guess seeing the common 14.7 AFR reading isn’t gonna happen, oh well. Thanks for all the help with this so far, I really appreciate it.

One last question, would monitoring the volts even be accurate/worth it? Or you would still have to take an average? I‘m not going to be tuning with this, but it‘d be nice to keep an eye on it. (I thought an output voltage of 0.2 represents a lean mixture, a reading of 0.8 represents a rich mixture and stoich is about 0.45 correct?)

darrylwaddy
Member
Posts: 4
Post Re: Air Fuel Ratio
on: November 7, 2019 (GMT)

Check the protocol. It may be the protocol is set wrong.

Find out how to get the protocol, because that is what I’m doing now for my Kia Soul. If you find it, go to:

Settings
Vehicle profile
Scroll to bottom, tap advance settings
Scroll to bottom and tap preferred obd II protocol
Then go from there.

This is what I learned from a YouTube video

https://youtu.be/sS_CPrwMj5U

I hope this helps

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