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 Post subject: Front O2 sensor limit
PostPosted: Wed Mar 07, 2007 11:19 am 
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We have all seen in logging that the front o2 reads as rich as a reported .75 lambda (11.025 afr) and no more. I've found that this limit can be changed in both the 16bit and 32bit ecus. The value is effectively capped even if the calculated value is richer. Question is, would this be useful at all for those without an aftermarket wideband o2 or a waste of time?


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PostPosted: Wed Mar 07, 2007 11:27 am 
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While logging my afr's on a 04wrx my front O2 is only ~.1 off from the wideband I was using. It would be helpful so that way you could effectively calibrate the stock front O2 using a wideband, then only have to use the front O2 to datalog and get an accurate picture of the afr's your running. Even if that would mean moving the front O2 to the downpipe to help reduce pressure differences found pre-turbo. I personally think it would be great!


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PostPosted: Wed Mar 07, 2007 12:16 pm 
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+1 on thinking this would be great. If nothing else it opens the door for people to do more testing of the sensor's accuracy so it can either be proved or disproved that it can be used for tuning.


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 Post subject:
PostPosted: Wed Mar 07, 2007 12:30 pm 
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I'm wondering how consistant the sensor could be.. testing would be a great but I'm pessimistic of how useful it would be.

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 Post subject:
PostPosted: Wed Mar 07, 2007 12:49 pm 
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Well, anyone with a wideband that wishes to test just PM me your rom.


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 Post subject:
PostPosted: Wed Mar 07, 2007 2:41 pm 
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I say let anyone change the cap to 0.68 if he wants. I can't see how this could hurt anything.


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 Post subject:
PostPosted: Wed Mar 07, 2007 2:57 pm 
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Well more of question if it worthwile or not. It's isn't going to negatively impact anything. But I don't want to waste my time adding it to 120 roms if it is useless.


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 Post subject:
PostPosted: Wed Mar 07, 2007 3:19 pm 
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merchgod wrote:
But I don't want to waste my time adding it to 120 roms if it is useless.
I see. In that case, just do the 32-bit ECUs, since the sensor used with the 16-bit ECUs doesn't read below 11:1 anyhow.


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 Post subject:
PostPosted: Wed Mar 07, 2007 3:23 pm 
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I am going to finish my wideband install this weekend. I already have most of the wiring done so I should finish it up on Saturday, hopefully. I can do some testing on this if it helps people. I have logged my stock sensor in the past and based on what I am dialing in the map, it reads way richer than what my map calls for. I'll be able to verify this once the sensor is installed. Merch, I can PM you once I am ready to do the test.

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 Post subject:
PostPosted: Wed Mar 07, 2007 3:25 pm 
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Jon [in CT] wrote:
merchgod wrote:
But I don't want to waste my time adding it to 120 roms if it is useless.
I see. In that case, just do the 32-bit ECUs, since the sensor used with the 16-bit ECUs doesn't read below 11:1 anyhow.


Nevermind. Beat me to it :D

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 Post subject:
PostPosted: Wed Mar 07, 2007 3:36 pm 
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Are you going to relocate it after the turbo? If not it will read leaner when you are running lean and richer when you are running rich because of the pressure.


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 Post subject:
PostPosted: Wed Mar 07, 2007 4:21 pm 
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Jon [in CT] wrote:
merchgod wrote:
But I don't want to waste my time adding it to 120 roms if it is useless.
I see. In that case, just do the 32-bit ECUs, since the sensor used with the 16-bit ECUs doesn't read below 11:1 anyhow.

Ahh, ok.

Well, if anyone wants to try it out, just PM me your rom. If it at least is somewhat useful then I'll add it to the next defs.


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 Post subject:
PostPosted: Wed Mar 07, 2007 4:36 pm 
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I'll send my ROM when I get home. I've been meaning to do some tuning.

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 Post subject:
PostPosted: Fri Mar 09, 2007 11:59 pm 
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Ok, I just realized that the front o2 scaling tables (both 16bit and 32bit) are only scaled to an AFR of 11:1. So, regardless of whether the limit is changed, it won't read any richer unless the table was rescaled. This would require logging the raw data from the front o2 and corresponding it to an AFR on an aftermarket wideband o2. Guess we'll have to wait until support is added for widebands to the logger.


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 Post subject:
PostPosted: Sat Mar 10, 2007 12:03 am 
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Can you not just rescale the sensor map? Change the column lower, and just assume it is linear further down?


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