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This is a separate thread from RAX Fast Logging, as it doesn't concern every RAX user... and can be a tricky business to set up.


Some of you have pulled out your factory rear O2 sensor, and used that ECU ADC input for reading analogue voltage from a wideband. When it comes to logging "Rear O2" voltage, there's a niggle...

According to tephra, the traditional "Rear O2" logging variable includes a sensor supply voltage offset. The ECU reads the "sensor input" AND a "supply voltage"... and subtracts one from the other to give you the end result. That supply voltage is apparently 0.5V on the factory sensor wiring. If your wideband is wired up separately with 0V ground, the traditional "Rear O2" reading isn't fit for AFR conversion.

Because of this, you'll likely be logging a different address to get AFR... the "RAW sensor input" variable, instead of the regular "Rear O2" voltage. We have to pull a similar stunt here.


Here is how you go about integrating your rear-O2 wiring patch with RAX Fast Logging, in order to get that tasty AFR in your logs...



Revise your MUT 3C Address in the MUT Table

In EcuFlast, edit your MUT table.



Slot the following address into cell 3C:

For ROMID... enter Value in MUT 3C...
52360018.........0x80933D
52680015-22......0x809345
52680024.........0x809349
52690019-22......0x809345
53040010.........0x80933D
53050006-7.......0x80933D
53050009.........0x80933D
53600010.........0x80935D
53610010.........0x809355
53610013.........0x80942D
54060007-8.......0x80935D
54070007.........0x80935D
55570005-6.......0x809439
55580005-6.......0x809439
55590006.........0x809439
56180001-2.......0x80942D
56890007.........0x809451
56890009-10......0x80945D
56890013.........0x80945D
56900007.........0x809451
56900009-10......0x80945D
56910007.........0x809451
56920006.........0x809451
56940007.........0x809451
56950006.........0x809451
57140001.........0x809455
580x0005.........0x809471
59580004.........0x80946F


With this edit, MUT 3C will then be "wideband-ified rear O2 Volts", instead of "useless rear O2 Volts". RAX Fast Logging will do the rest.

Reflash your ROM.



Add a New Logging Item to EvoScan RAX Fast Logging

Don't edit any of the existing items... just add a new one.

If you're handy with XML editing, start with this...

Code:
        <DataListItem DataLog="Y" Priority="1" Color="#000000" Display="O2AFR" LogReference="O2AFR" RequestID="CALC" Eval="[O2Sensor2]*[B]0.12345[/B]+[B]12345[/B]" Unit="a/f ratio" MetricEval="" MetricUnit="" ResponseBytes="4" GaugeMin="8" GaugeMax="18" ChartMin="8" ChartMax="18" ScalingFactor="1" Notes="" Visible="False" LogHide="false" />
Alternatively, use "Edit Data Items" in EvoScan, then hit "Add New Item"...




Adjust the "O2AFR" Item Formula

You'll then need to revise the formula to convert O2Sensor2's 0-5V value to AFR.

Instead of my place-holder "[O2Sensor2]*0.12345+12345" formula, set up the right one for your wideband analogue output.

I can't tell you what that should be. Looks like it's MATHS TIME! :)



That should do the trick. Let me know how it goes.

Rich
 

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I really like this rich guy. Unfortunately I still just log AFR from a serial cable but I suppose it would be a good idea to finally just tackle this project.

Thanks again for your amazing contributions.
 

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You're alright in my book, Rich...I don't care what they say about you..haha

Everything works perfectly. The log shows exactly what my wideband gauge is showing. Thank you sir!
 

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Discussion Starter · #5 ·
Folks, as you get this working, can you please post up:

  • Wideband brand/model
  • Analogue output configuration
  • Your EvoScan "Eval" formula to convert O2Sensor2 Volts to AFR

That'll help the "mathematically challenged" (as RS200Z succinctly put it, lol).

Rich
 

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I use the AEM Analog Wideband. White analog + output wire to yellow rear O2 sensor wire. Brown analog - output wire to chassis ground.


This is how I have it setup in Evoscan and it works perfectly
 

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Hmmm I'm going to attempt this. Wish my newb-self luck!
 

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I have an AEM UEGO, "old" digital type with the 0-5 V analog output tapped into my rear O2 line. The formula that is working the best so far is [O2Sensor2]*2+9.5 or something like that.

I'll report back if it needs any adjusting, but it seems to match the gauge as it sweeps with the engine off.
 

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This is a separate thread from RAX Fast Logging, as it doesn't concern every RAX user... and can be a tricky business to set up.


Some of you have pulled out your factory rear O2 sensor, and used that ECU ADC input for reading analogue voltage from a wideband. When it comes to logging "Rear O2" voltage, there's a niggle...

According to tephra, the traditional "Rear O2" logging variable includes a sensor supply voltage offset. The ECU reads the "sensor input" AND a "supply voltage"... and subtracts one from the other to give you the end result. That supply voltage is apparently 0.5V on the factory sensor wiring. If your wideband is wired up separately with 0V ground, the traditional "Rear O2" reading isn't fit for AFR conversion.

Because of this, you'll likely be logging a different address to get AFR... the "RAW sensor input" variable, instead of the regular "Rear O2" voltage. We have to pull a similar stunt here.


Here is how you go about integrating your rear-O2 wiring patch with RAX Fast Logging, in order to get that tasty AFR in your logs...



Revise your MUT 3C Address in the MUT Table

In EcuFlast, edit your MUT table.



Slot the following address into cell 3C:

For ROMID... enter Value in MUT 3C...
52360018.........0x80933D
52680015-22......0x809345
52680024.........0x809349
52690019-22......0x809345
53040010.........0x80933D
53050006-7.......0x80933D
53050009.........0x80933D
53600010.........0x80935D
53610010.........0x809355
53610013.........0x80942D
54060007-8.......0x80935D
54070007.........0x80935D
55570005-6.......0x809439
55580005-6.......0x809439
55590006.........0x809439
56180001-2.......0x80942D
56890007.........0x809451
56890009-10......0x80945D
56890013.........0x80945D
56900007.........0x809451
56900009-10......0x80945D
56910007.........0x809451
56920006.........0x809451
56940007.........0x809451
56950006.........0x809451
57140001.........0x809455
580x0005.........0x809471

With this edit, MUT 3C will then be "wideband-ified rear O2 Volts", instead of "useless rear O2 Volts". RAX Fast Logging will do the rest.

Reflash your ROM.



Add a New Logging Item to EvoScan RAX Fast Logging

Don't edit any of the existing items... just add a new one.

If you're handy with XML editing, start with this...

Code:
        <DataListItem DataLog="Y" Priority="1" Color="#000000" Display="O2AFR" LogReference="O2AFR" RequestID="CALC" Eval="[O2Sensor2]*[B]0.12345[/B]+[B]12345[/B]" Unit="a/f ratio" MetricEval="" MetricUnit="" ResponseBytes="4" GaugeMin="8" GaugeMax="18" ChartMin="8" ChartMax="18" ScalingFactor="1" Notes="" Visible="False" LogHide="false" />
Alternatively, use "Edit Data Items" in EvoScan, then hit "Add New Item"...




Adjust the "O2AFR" Item Formula

You'll then need to revise the formula to convert O2Sensor2's 0-5V value to AFR.

Instead of my place-holder "[O2Sensor2]*0.12345+12345" formula, set up the right one for your wideband analogue output.

I can't tell you what that should be. Looks like it's MATHS TIME! :)



That should do the trick. Let me know how it goes.

Rich
Unfortunately, I do not see my Rom ID: 59590004 (2013 MR). What should I do?
 

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Discussion Starter · #11 ·
I haven't written RAX Patch for any 2013 ROMs yet.

Rich
 

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I have an AEM UEGO, "old" digital type with the 0-5 V analog output tapped into my rear O2 line. The formula that is working the best so far is [O2Sensor2]*2+9.5 or something like that.

I'll report back if it needs any adjusting, but it seems to match the gauge as it sweeps with the engine off.
+1

I use [O2Sensor2]*2+9.8 and its very close
 

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I really like this rich guy. Unfortunately I still just log AFR from a serial cable but I suppose it would be a good idea to finally just tackle this project.
To me, this is the preferred method. That means the wideband data stays digital the entire time. It's better than trying to convert analog back into digital and losing some precision in the mix.
 

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To me, this is the preferred method. That means the wideband data stays digital the entire time. It's better than trying to convert analog back into digital and losing some precision in the mix.
x2

Reported AFR values tend to drift from dead-on to lean for me when I rely on rear O2 analog logging. It's just too inconsistent to use for fuel tuning, but is OK to know if your tune is still sane if you're doing constant logging with the OP2.
 

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Discussion Starter · #16 ·
Yeah, and I'm making progress. I've done the 2013 USDM Ralliart patches already, but as yet I haven't found a suitable test subject for them. :)

Evo X SST and 5MT will be done before too long.

Rich
 

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Finally got around to doing this and have noticed sometimes I get no signal other times I do. When it works its dead on but when it doesn't it sees 0 to 0.1xxx voltage. Power cycling the car on and off doesn't seem to fix it but if car is off for a while and I go back out to it it magically starts working again.

Has anyone else see this issue? I really don't think its my wideband but of course you never know. Just wondering what other have seen.

ROM 56890010.
 

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Unfortunately, I do not see my Rom ID: 59590004 (2013 MR). What should I do?
Same here, nothing for 13 MR yet?

Great work btw!
 

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Discussion Starter · #19 ·
Okay, I'll get on it. :)

Rich
 

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Donations to rich always seem to help out in these situations ;)
 
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