Originally Posted by Robb235

How to Monitor Air/Fuel Ratios (California Emissions Vehicles Only)

Ok, so yesterday I was fooling around with how to read AFR on Engine Link. I've got a '99 4Runner that has California style emissions, which means that there is a an "Air Fuel Ratio Sensor" instead of the normal narrowband oxygen sensor. To see if you have an Air Fuel Ratio Sensor equipped on your rig, take a look at your exhaust pipes, and if you have 2 catalytic converters, you've got the wideband AFR sensor. If you only have 1 catalytic converter, then you've got the narrowband sensor, meaning this part of the write up will not work for you (sorry).

Some 4Runners have the ability to monitor the air fuel ratio directly from the ECU. All that's needed is a custom PID and formula. This only works on some rigs, while it doesn't work on others. Unfortunately this did not work on my '99. I suspect it only works on 2001 and newer, but I'm not positive. At any rate, try the following custom PID and see if it works for you:

ECU address or Header: 0
ModeandPID: 0124
Formula: A*(1465/80)
Min Value: 10
Max Value: 20
Description: Air Fuel (or water you want to call it)
Unit: Ratio

If the above works for you, then you're finished. However, if you're like me and the above does not work for you, there's another, more roundabout way to view your AFRs.

Using this method, we're going to create two new custom PIDs. One will be for lean AFRs, the other will be for rich AFRs. Create the following:

ECU address or Header: 0
ModeandPID: 0114
Formula: A*(15/200)+4.8
Min Value: 10 (or however low you want it to go)
Max Value: 14.7 (this MUST be 14.7)
Description: AFR (Rich)
Unit: Ratio


ECU address or Header: 0
ModeandPID: 0114
Formula: A*(30/200)-5.1
Min Value: 14.7 (this MUST be 14.7)
Max Value: 20 (or however high you want it to go)
Description: AFR (Lean)
Unit: Ratio

Now that you've created your two custom PIDs (one for "rich" and one for "lean") go back to your gauge screen. Hold down on the gauge screen until the menu pops up, and select "Big Bar" (selecting "Small Bar" will work too). Place the AFR Rich gauge on the left side of the screen. Do the same thing again, and place the AFR Lean on the right side of the screen, as pictured below:



Now you can monitor what your actual AFRs are. When you're rich, only pay attention to the value on the "Rich" gauge. And when you're lean, only pay attention to the value on the "Lean" gauge.


Here I'm running right at 14.7


Here I'm running at 13.12 (ignore the 11.55 value)


Here I'm running at 15.6 (ignore the 15.15 value)


Hope that helps! Let me know if you have any questions.

Originally Posted by omegatek

So is there a consensus on the formula?



Is it: Formula: A*(9/5)-38 or is it Formula: A*(9/5)-40

Originally Posted by PoRunner

This is awesome info guys. Thanks for figuring this out with the trans temp. It's working like a charm on my 00' Limited.

I browsed through the thread again and didn't stumble upon a way to monitor fuel level. Am I correct at understanding the 00' Limited does not provide this through ECU feedback?

Originally Posted by Robb235

I went back and added to the original post. Now there's a write up included for how to monitor your Air Fuel Ratio. This only applies to vehicles with an AFR sensor instead of the traditional narrowband O2 sensor.

Here's the new section of the write up:

Originally Posted by TheOGConCon

So to clarify, my 4Runner is what I think would be designated as a 98.5 Limited... do I have the necessary trans temp sensor to monitor the running temp or do I just have the sensor for the idiot light??

Originally Posted by Robb235

Do you have the '99+ upgrades? "Fat lip" bumper, cup holders in the center console, etc.?

Originally Posted by TheOGConCon

Yes, those, the multi-mouse 4WD, along with everything else listed in the upgrades for the 99 model year.

On a side note, I tried out the PID for transmission temp listed at the beginning of this thread (-40, not -38), and it was telling me there was no data, but there were two other Trans temp sensors that came with Torque Pro, and the second one was reading a temp. Would that be it? I didn't run my truck for long to see what kind of operating temps I would get, but I'll be doing some driving around here in a couple hours so I can see what it'll read.

Originally Posted by Robb235

Sounds like your 4Runner is similar to mine; '99 Limited model with multi-mode. You should have the transmission temp info available to you.

I'm not familiar with Torque Pro, as I think that app is for Android phones (I'm using Engine Link for the iPhone). What PID is registering as transmission temp for you?

Originally Posted by TheOGConCon

Disregard what I said in my first post, it was my mistake why the added PID want working, I had one of the numbers in wrong. I'm now seeing transmission temps!! Yay!

Originally Posted by Slowgoat

Cool thread. I may switch back to Iphone, so it is nice to see there is an option for this.

Is there a sensor for oil temp or oil pressure?

Never could get one for Torque/Android.

I was led to believe it was not available, but didn't know if one day it might be possible.

Thanks for everyone's hard work on this!