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-   -   Target Air Fuel Ratio for ScanGauge in my 97. (https://www.toyota-4runner.org/3rd-gen-t4rs/279126-target-air-fuel-ratio-scangauge-my-97-a.html)

19963.4lsr5 10-29-2019 03:05 PM

Target Air Fuel Ratio for ScanGauge in my 97.
 
Target AF Ratio for B1S1 for my 97 with the 3.4. It works.

TXD 686AF10106
RXF 044145060000
RXD 2808
MTH 05B900800000
Name A/F


Edit: I just corrected the TXD and RXF to show the 06 memory location instead of the 05.

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19963.4lsr5 11-02-2019 10:26 PM

Just so you all know. Running an engine temp colder than 191f will not achieve the 14.7:1 air fuel ratio. It has to be 191 or higher.

I blocked 6” of my rad and I am still running 186-191 this time of year in PA. I’d like to get it to 195. I wonder if flipping the thermostat the wrong way will do it.


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Toy2play 11-02-2019 10:38 PM

Quote:

Originally Posted by 19963.4lsr5 (Post 3382394)
Just so you all know. Running an engine temp colder than 191f will not achieve the 14.7:1 air fuel ratio. It has to be 191 or higher.

I blocked 6” of my rad and I am still running 186-191 this time of year in PA. I’d like to get it to 195. I wonder if flipping the thermostat the wrong way will do it.


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Everything I've read has said that it's not very accurate to try and get afr readings off the stock O2 sensor. Not sure what you are meaning that you cant get 14.7 unless you are higher that 191 temp, I have an aftermarket afr gauge and welded bung in the exhaust and bounces around 14.7 ratio well under 191 temp. Am I missing something here? I run a super charger and with a cooler thermostat. Normal operating temps for me is 181. Are you basing your findings on your scan gauge readings?

brillo_76 11-02-2019 10:45 PM

Quote:

Originally Posted by 19963.4lsr5 (Post 3382394)
Just so you all know. Running an engine temp colder than 191f will not achieve the 14.7:1 air fuel ratio. It has to be 191 or higher.

I blocked 6” of my rad and I am still running 186-191 this time of year in PA. I’d like to get it to 195. I wonder if flipping the thermostat the wrong way will do it.


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I would say you would gain a few degrees by putting the jiggler at 12 o'clock instead of 6. Good to know that 191 up required for 14.7: 1 ratio.


Your thermostat isn't stick open is it?

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19963.4lsr5 11-02-2019 11:27 PM

Quote:

Originally Posted by Toy2play (Post 3382404)
Everything I've read has said that it's not very accurate to try and get afr readings off the stock O2 sensor. Not sure what you are meaning that you cant get 14.7 unless you are higher that 191 temp, I have an aftermarket afr gauge and welded bung in the exhaust and bounces around 14.7 ratio well under 191 temp. Am I missing something here? I run a super charger and with a cooler thermostat. Normal operating temps for me is 181. Are you basing your findings on your scan gauge readings?



It’s the target AF ratio not the actual.


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19963.4lsr5 11-02-2019 11:28 PM

Quote:

Originally Posted by brillo_76 (Post 3382412)
I would say you would gain a few degrees by putting the jiggler at 12 o'clock instead of 6. Good to know that 191 up required for 14.7: 1 ratio.


Your thermostat isn't stick open is it?

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I get up to temp in around 2-3 miles when it’s in the low 30’s outside.


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Toy2play 11-02-2019 11:42 PM

Quote:

Originally Posted by 19963.4lsr5 (Post 3382433)
It’s the target AF ratio not the actual.


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I still a bit confused by your post. I'm not sure the purpose of saying that you cant achieve 14.7:1 unless you are over 191 degrees. I know very little about afr, but have been forced to get a better understanding because of the supercharger. I'm just trying to grasp your statement since my afr gauge does not show that at all. Are you saying that your afr is not 14.7:1 ratio under 191 engine temp? If so, where are you getting this reading?

19963.4lsr5 11-03-2019 12:35 AM

Target Air Fuel Ratio for ScanGauge in my 97.
 
Quote:

Originally Posted by Toy2play (Post 3382436)
I still a bit confused by your post. I'm not sure the purpose of saying that you cant achieve 14.7:1 unless you are over 191 degrees. I know very little about afr, but have been forced to get a better understanding because of the supercharger. I'm just trying to grasp your statement since my afr gauge does not show that at all. Are you saying that your afr is not 14.7:1 ratio under 191 engine temp? If so, where are you getting this reading?



I’m getting the reading from the above PID settings VIA my ScanGauge.

When the engine cold starts it’s target air fuel ratio is really rich. In the weather I’m having it starts out around 7 to 8. It slowly ramps up the target AFR as the engine warms up around 1 min into this the engine goes closed loop and starts using the front O2 sensor to achieve the target AFR. The warmer the engine the higher the target. It uses the O2 sensor and the LTFT and STFT to achieve the target AFR. When the engine hits 191f the target AFR is at 14.7. 188f engine temp is around 14.4 AFR as an example.

I don’t know your year buy my 97 would have the target AFR around 14.0 at 181. I can verify that in the morning by watching the engine temp and AFR target at the same time.


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brillo_76 11-03-2019 06:36 AM

Quote:

Originally Posted by 19963.4lsr5 (Post 3382434)
I get up to temp in around 2-3 miles when it’s in the low 30’s outside.


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Ok. Just wanted to check. :]

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Black798 11-03-2019 10:08 AM

1 Attachment(s)
Prior to I beleive 1999 Toyota used narrowband o2 sensors in all the 4runners. These sensors don't understand afr they only read on a 0 to 1v scale that is either rich or lean. I have an AEM afr gauge installed in my truck and I hit 14.7 afr almost immediately after startup and it hovers there untill my tune takes over in boost. Not really understanding the purpose of having a "target afr" reading on the scangauge. Also attached a graph showing how narrowband o2s read

Toy2play 11-03-2019 11:03 AM

Quote:

Originally Posted by 19963.4lsr5 (Post 3382459)
I’m getting the reading from the above PID settings VIA my ScanGauge.

When the engine cold starts it’s target air fuel ratio is really rich. In the weather I’m having it starts out around 7 to 8. It slowly ramps up the target AFR as the engine warms up around 1 min into this the engine goes closed loop and starts using the front O2 sensor to achieve the target AFR. The warmer the engine the higher the target. It uses the O2 sensor and the LTFT and STFT to achieve the target AFR. When the engine hits 191f the target AFR is at 14.7. 188f engine temp is around 14.4 AFR as an example.

I don’t know your year buy my 97 would have the target AFR around 14.0 at 181. I can verify that in the morning by watching the engine temp and AFR target at the same time.


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I appreciate the explanation. As per my afr gauge, mine also runs rich at first, but bounces around 14.7 fairly quick which is normal. I dont think you are getting an accurate reading with the scan gauge. Mine is also a 97. To make the engine run hotter so that you can achieve stoich seems a little extreme in this case. I dont believe you are getting an accurate reading. Even my afr bounces around quite a bit at idle/cruising within a seconds time it can change 2 or 3 times from 14.5 to 14.9 range with some 14.7, 14.8 in the mix. I have my doubts that what you are seeing is really 14.0 on the scan gauge at 181 degrees.

I think it's a bit of a stretch to say that you cant achieve stoich unless your temps are over 191. I mean no disrespect, imo I just think you are making assumptions on data that isnt true. I mean it wouldnt be hard for the ECU to regulate the afr for a 10 degree variance in engine temp. It does it at quite a bit lower temperatures just fine based off my wideband O2 sensor that I installed.

Toy2play 11-03-2019 11:17 AM

Quote:

Originally Posted by Black798 (Post 3382542)
Prior to I beleive 1999 Toyota used narrowband o2 sensors in all the 4runners. These sensors don't understand afr they only read on a 0 to 1v scale that is either rich or lean. I have an AEM afr gauge installed in my truck and I hit 14.7 afr almost immediately after startup and it hovers there untill my tune takes over in boost. Not really understanding the purpose of having a "target afr" reading on the scangauge. Also attached a graph showing how narrowband o2s read

I've even heard the 99+ runners that have a wideband O2 sensor are not reliable either. Everything I read came to the same conclusion, you need to install an aftermarket wideband sensor to get any accurate reading.

19963.4lsr5 11-03-2019 04:27 PM

Quote:

Originally Posted by Toy2play (Post 3382580)
I've even heard the 99+ runners that have a wideband O2 sensor are not reliable either. Everything I read came to the same conclusion, you need to install an aftermarket wideband sensor to get any accurate reading.



Yes, it is not ever to be used as an actual sensor. I was just curious if the parameter was available like on my Saturn, And if it behaved like it. That’s why I kept calling it target.


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19963.4lsr5 11-03-2019 06:19 PM

Here is the target AF slowly increasing during warmup. https://uploads.tapatalk-cdn.com/201...b0217ace69.jpghttps://uploads.tapatalk-cdn.com/201...dc4d5777ba.jpghttps://uploads.tapatalk-cdn.com/201...af0f997492.jpghttps://uploads.tapatalk-cdn.com/201...94b84fecd8.jpghttps://uploads.tapatalk-cdn.com/201...ae8a800a1c.jpg


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19963.4lsr5 11-03-2019 06:55 PM

Target Air Fuel Ratio for ScanGauge in my 97.
 
Quote:

Originally Posted by Black798 (Post 3382542)
Prior to I beleive 1999 Toyota used narrowband o2 sensors in all the 4runners. These sensors don't understand afr they only read on a 0 to 1v scale that is either rich or lean. I have an AEM afr gauge installed in my truck and I hit 14.7 afr almost immediately after startup and it hovers there untill my tune takes over in boost. Not really understanding the purpose of having a "target afr" reading on the scangauge. Also attached a graph showing how narrowband o2s read



I found it and put it on the ScanGauge to see if it behaved like my saturns. Stoch on a 0-1v Sensor is .50v. But it’s not near as accurate as a wide band and you need a a way to average the high and low swing to see what the AF Ratio is.

Tuning with a narrow band in the 90’s before wide band sensors and displays became available I shot for .4v to .5v in cruise mode and .92v at wide open throttle.


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