how-to: Log AFR from the LC-1 w/o a serial cable
Apr 1, 2018, 11:38 AM
#496
Evolved Member
Well if you know the V into the ecu is changing, but in your log it is not, then i would guess its probably the evoscan formula that needs tweaking. Try and insert a formula that just gives you the raw voltage on that input and once that is working try building out the formula to convert that to your afr number. Request ID "3C" function "0.01952*x"
What would be gauge min and gauge max values or it will log any how if i dont fill in those fields ?
Apr 1, 2018, 12:20 PM
#497
EvoM Community Team Leader
The X will be the numeric value that the ECU is sending for request "3C". 3C should be the mut address for the stored value of the rear oxygen sensor input. That formula will convert that number into a voltage. If you look in evoscan there is actually already an entry for this by default labeled "Oxygen Sensor #2". What it gives you is a raw voltage, you can interpret that yourself in your logs, right a formula in excel to convert it, or get the formula right in evoscan to convert it there.
Apr 1, 2018, 12:34 PM
#498
EvoM Community Team Leader
Getting super specific Your logger sends 3C to the ecu. This tells the ecu that we want the value stored at the 3C address in the mut table, it then responds with the stored value, which will in this case be one byte. A byte can represent the number 0-255. The input associated with 3C (rear 02 sensor) has a 0-5v(ish) input range. That means the ecu can only respond with 255 different voltages (8-bit precision). If you devide 5 by 255 you get 0.019607 which is really close to that formula in evoscan. The evoscan one probably being more accurate because the ADC probably isn't exactly 0-5v.
So that gives you the raw voltage, you then have to take that raw voltage and run it through the equation that AEM is giving you to convert it to AFR. You can take their equation and translate it into the function evoscan uses. I believe its basically the same as writing formula's in excel / spread sheet apps. In evoscan x just represents the value the ecu is sending. You putting x tells evoscan to fill in the blank.
EDIT: Im dumb its 0-255 but that represents 256 positions, 0 is a number. So 5 divided by 256 is exactly 0.01953125 much closer to evoscan.
So that gives you the raw voltage, you then have to take that raw voltage and run it through the equation that AEM is giving you to convert it to AFR. You can take their equation and translate it into the function evoscan uses. I believe its basically the same as writing formula's in excel / spread sheet apps. In evoscan x just represents the value the ecu is sending. You putting x tells evoscan to fill in the blank.
EDIT: Im dumb its 0-255 but that represents 256 positions, 0 is a number. So 5 divided by 256 is exactly 0.01953125 much closer to evoscan.
Last edited by Biggiesacks; Apr 1, 2018 at 12:39 PM.
Apr 1, 2018, 12:35 PM
#499
Evolved Member
The X will be the numeric value that the ECU is sending for request "3C". 3C should be the mut address for the stored value of the rear oxygen sensor input. That formula will convert that number into a voltage. If you look in evoscan there is actually already an entry for this by default labeled "Oxygen Sensor #2". What it gives you is a raw voltage, you can interpret that yourself in your logs, right a formula in excel to convert it, or get the formula right in evoscan to convert it there.
Apr 2, 2018, 09:11 AM
#500
Interesting read
http://aemelectronics.com/?q=forum/b...ignalmaxed-out
May need to have a replacement sent.
http://aemelectronics.com/?q=forum/b...ignalmaxed-out
May need to have a replacement sent.
Aug 10, 2018, 01:02 PM
#501
Figured id update this since I still couldnt find the info posted anywhere and my experience. AEM X-Series btw.
The formula AEM shows works, SORTA. Just like the UEGO the diplayed afr by the gauge doesnt match the logged voltage and this is where you need to tweak things. If you just insert the AEM formula and also log voltage and compare they are dead on with each other, but not what the gauge is displaying.
0.01952*x*2.3750+7.315 is the AEM Formula
0.01952*x*2.4750+7.315 is what i ended up with and im within 0.1AFR You need to log and compare and make adjustments to the formula for me, i wasnt really concerned with anything more than making sure it was logging accurately in the 10-13afr range.
Also make sure the BROWN wire is ran to Sensor Ground!
The formula AEM shows works, SORTA. Just like the UEGO the diplayed afr by the gauge doesnt match the logged voltage and this is where you need to tweak things. If you just insert the AEM formula and also log voltage and compare they are dead on with each other, but not what the gauge is displaying.
0.01952*x*2.3750+7.315 is the AEM Formula
0.01952*x*2.4750+7.315 is what i ended up with and im within 0.1AFR You need to log and compare and make adjustments to the formula for me, i wasnt really concerned with anything more than making sure it was logging accurately in the 10-13afr range.
Also make sure the BROWN wire is ran to Sensor Ground!
Aug 10, 2018, 08:50 PM
#502
Evolved Member
Figured id update this since I still couldnt find the info posted anywhere and my experience. AEM X-Series btw.
The formula AEM shows works, SORTA. Just like the UEGO the diplayed afr by the gauge doesnt match the logged voltage and this is where you need to tweak things. If you just insert the AEM formula and also log voltage and compare they are dead on with each other, but not what the gauge is displaying.
0.01952*x*2.3750+7.315 is the AEM Formula
0.01952*x*2.4750+7.315 is what i ended up with and im within 0.1AFR You need to log and compare and make adjustments to the formula for me, i wasnt really concerned with anything more than making sure it was logging accurately in the 10-13afr range.
Also make sure the BROWN wire is ran to Sensor Ground!
The formula AEM shows works, SORTA. Just like the UEGO the diplayed afr by the gauge doesnt match the logged voltage and this is where you need to tweak things. If you just insert the AEM formula and also log voltage and compare they are dead on with each other, but not what the gauge is displaying.
0.01952*x*2.3750+7.315 is the AEM Formula
0.01952*x*2.4750+7.315 is what i ended up with and im within 0.1AFR You need to log and compare and make adjustments to the formula for me, i wasnt really concerned with anything more than making sure it was logging accurately in the 10-13afr range.
Also make sure the BROWN wire is ran to Sensor Ground!
Thanks.
Aug 25, 2018, 04:50 AM
#505
Evolved Member
Any other reliable wide band in the market which can be logged using the same technique ?
Aug 25, 2018, 08:12 AM
#507
EvoM Community Team Leader
I tried using the formula given in this photo. The Voltage output doesnt go below 3v and is mostly stuck at 4.9v which clearly seems to be sensor error. I tried ECU sensor ground, chassis ground but it does the same thing. The gauge some times show 25- 30 AFR like WTF ?
Any other reliable wide band in the market which can be logged using the same technique ?
Any other reliable wide band in the market which can be logged using the same technique ?
Aug 25, 2018, 08:25 AM
#508
Evolved Member
Aug 26, 2018, 10:05 AM
#509
EvoM Community Team Leader
Aug 26, 2018, 04:43 PM
#510
Two things, first make sure you have your MUT table setup correctly. Second, see if you have Voltage out from the gauge. Disconnect the analog out and see if you are reporting voltage on that wire and that its changing and some what matches the table AEM gives. Again my displayed voltage didnt match the volts output before even hooking to the ecu. Once i knew the gauge was sending the volts out signal, i just logged that raw and compared to my logged afr using the formula AEM provided and in my link above. Obviously the logged volts and logged afr matched, but not the displayed afr of the gauge. Thats why i had to tweak the formula.