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Series I Engine Tuning Forum EMS (Flash Tuning, Interceptor, Piggy Back, Stand Alone)

HELP: AFR too lean

Old Sep 9, 2009 | 10:06 PM
  #1  
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HELP: AFR too lean

Tried logging the data from O2S1 using OBDKey Bluetooth and here is what I got:
~mA~~~ EQ Ratio~~RPM
-0.121~~0.970~~~~1042
-0.027~~0.993~~~~1099
-0.238~~0.945~~~~1140
-0.215~~0.949~~~~1200
-0.051~~0.986~~~~1214
0.227~~1.097~~~~1241
0.113~~1.041~~~~1267
-0.188~~0.955~~~~1390
-0.102~~0.974~~~~1764
-0.098~~0.976~~~~2232
-0.152~~0.962~~~~2750
-0.414~~0.908~~~~3320
-0.727~~0.852~~~~3886
-0.316~~0.928~~~~4500
-0.504~~0.890~~~~5085
-0.363~~0.918~~~~5727
-0.512~~0.889~~~~6359
-0.535~~0.885~~~~6967
-0.820~~0.836~~~~7549
-0.543~~0.884~~~~8031
-0.418~~0.907~~~~8594
0.555~~~1.256~~~~8822

According to:
To convert EQ Ratio to AFR, use: AFR = {stoich}/EQ

To convert Lambda to AFR, use: AFR = Labmda/{stoich}

To convert AFR to EQ Ratio, use: EQ Ratio = {stoich}/AFR

To convert Lambda to EQ Ratio, use: EQ Ratio = 1/Lambda

To convert EQ Ratio to Lambda, use: Lambda = 1/EQ Ratio

I assume that the Stoich for RON97 petrol is 14.1 and apply "14.1/EQ Ratio". Is this equal to {14.1}/EQ Ratio? not sure what is the curly bracket means.

And my AFR looks way too lean.
Attached Thumbnails HELP: AFR too lean-afr_14.1stoich.jpg  
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Old Sep 9, 2009 | 10:42 PM
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From: Smallville
#'s below Lamba 1.00 are rich.....

Stoich is closer to 14.7 AFR
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Old Sep 10, 2009 | 12:54 AM
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Originally Posted by dannobre
#'s below Lamba 1.00 are rich.....

Stoich is closer to 14.7 AFR
If I used divide the EQ Ratio by 14.7 stoich, it's even leaner...

Maybe the reading of OBDKey from stock O2S1 is Lambda instead of EQ Ratio. Then it makes sense.

The 1st graph in my previous post was calculated with {Stoich}/EQ Ratio, which is 14.1/EQ Ratio.

The 2nd graph here is assuming that the reading from OBDKey of O2S1 is Lambda and calculated with Lambda*14.7. This is assuming that the data is in Lambda, and the AFR looks correct.
Attached Thumbnails HELP: AFR too lean-afr.jpg  
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Old Sep 10, 2009 | 11:37 AM
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From: The Dark Side
OEM programming or are you running a custom map?
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Old Sep 10, 2009 | 12:16 PM
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From: CA, Rowland Hts.
it is in lambda. you're afr's look more or less normal depending on load.
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Old Sep 10, 2009 | 07:50 PM
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Originally Posted by Jedi54
OEM programming or are you running a custom map?
Knight Sports reflash
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Old Sep 11, 2009 | 06:11 AM
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Originally Posted by NgoRX8
it is in lambda. you're afr's look more or less normal depending on load.
So, the stock O2S1 read in Lambda? Thought it only read in mA and the OBDKey software did the conversion...
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