Wideband on E85. AFR differance?
Thread Starter
Joined: Jun 2009
Posts: 363
Likes: 1
From: San Antonio, TX
Wideband on E85. AFR differance? Im swapping to a carb setup and on E85/nitrous. my question is will my AEM UEGO wideband work for this? i was looking up widebands ( i want to run another one, one on each header) and i found on summit a wideband for E85. Anyone have any info on this? i wondering if the wideband i already have will be accurate for E85 or not. thanx
It will, you just have to recalculate the air/fuel ratio.
14.7 on gasoline is lambda, & 9.76 on E85 is also lambda.
You just have to calculate the reading to figure out what the E85 value is.
14.7 on gasoline is lambda, & 9.76 on E85 is also lambda.
You just have to calculate the reading to figure out what the E85 value is.
^ Lambda of 1.0 to be exact.
An O2 sensor is just that. It measures oxygen. The fuel does not matter. This is why they measure in lambda and not AFR. The AFR is calculated from Lambda based on fuel type.
The ideal lambda does not change based on fuel. The AFR however does, quite a bit.
If you can wrap your head around the numbers. It's easier to just log everything in lambda.
Lambda E85 AFR Gas AFR
0.500 4.880 7.350
0.510 4.978 7.497
0.520 5.075 7.644
0.530 5.173 7.791
0.540 5.270 7.938
0.550 5.368 8.085
0.560 5.466 8.232
0.570 5.563 8.379
0.580 5.661 8.526
0.590 5.758 8.673
0.600 5.856 8.820
0.610 5.954 8.967
0.620 6.051 9.114
0.630 6.149 9.261
0.640 6.246 9.408
0.650 6.344 9.555
0.660 6.442 9.702
0.670 6.539 9.849
0.680 6.637 9.996
0.690 6.734 10.143
0.700 6.832 10.290
0.710 6.930 10.437
0.720 7.027 10.584
0.730 7.125 10.731
0.740 7.222 10.878
0.750 7.320 11.025
0.760 7.418 11.172
0.770 7.515 11.319
0.780 7.613 11.466
0.790 7.710 11.613
0.800 7.808 11.760
0.810 7.906 11.907
0.820 8.003 12.054
0.830 8.101 12.201
0.840 8.198 12.348
0.850 8.296 12.495
0.860 8.394 12.642
0.870 8.491 12.789
0.880 8.589 12.936
0.890 8.686 13.083
0.900 8.784 13.230
0.910 8.882 13.377
0.920 8.979 13.524
0.930 9.077 13.671
0.940 9.174 13.818
0.950 9.272 13.965
0.960 9.370 14.112
0.970 9.467 14.259
0.980 9.565 14.406
0.990 9.662 14.553
1.000 9.760 14.700
1.010 9.858 14.847
1.020 9.955 14.994
1.030 10.053 15.141
1.040 10.150 15.288
1.050 10.248 15.435
1.060 10.346 15.582
1.070 10.443 15.729
1.080 10.541 15.876
1.090 10.638 16.023
1.100 10.736 16.170
1.110 10.834 16.317
1.120 10.931 16.464
1.130 11.029 16.611
1.140 11.126 16.758
1.150 11.224 16.905
1.160 11.322 17.052
1.170 11.419 17.199
1.180 11.517 17.346
1.190 11.614 17.493
1.200 11.712 17.640
An O2 sensor is just that. It measures oxygen. The fuel does not matter. This is why they measure in lambda and not AFR. The AFR is calculated from Lambda based on fuel type.
The ideal lambda does not change based on fuel. The AFR however does, quite a bit.
If you can wrap your head around the numbers. It's easier to just log everything in lambda.
Lambda E85 AFR Gas AFR
0.500 4.880 7.350
0.510 4.978 7.497
0.520 5.075 7.644
0.530 5.173 7.791
0.540 5.270 7.938
0.550 5.368 8.085
0.560 5.466 8.232
0.570 5.563 8.379
0.580 5.661 8.526
0.590 5.758 8.673
0.600 5.856 8.820
0.610 5.954 8.967
0.620 6.051 9.114
0.630 6.149 9.261
0.640 6.246 9.408
0.650 6.344 9.555
0.660 6.442 9.702
0.670 6.539 9.849
0.680 6.637 9.996
0.690 6.734 10.143
0.700 6.832 10.290
0.710 6.930 10.437
0.720 7.027 10.584
0.730 7.125 10.731
0.740 7.222 10.878
0.750 7.320 11.025
0.760 7.418 11.172
0.770 7.515 11.319
0.780 7.613 11.466
0.790 7.710 11.613
0.800 7.808 11.760
0.810 7.906 11.907
0.820 8.003 12.054
0.830 8.101 12.201
0.840 8.198 12.348
0.850 8.296 12.495
0.860 8.394 12.642
0.870 8.491 12.789
0.880 8.589 12.936
0.890 8.686 13.083
0.900 8.784 13.230
0.910 8.882 13.377
0.920 8.979 13.524
0.930 9.077 13.671
0.940 9.174 13.818
0.950 9.272 13.965
0.960 9.370 14.112
0.970 9.467 14.259
0.980 9.565 14.406
0.990 9.662 14.553
1.000 9.760 14.700
1.010 9.858 14.847
1.020 9.955 14.994
1.030 10.053 15.141
1.040 10.150 15.288
1.050 10.248 15.435
1.060 10.346 15.582
1.070 10.443 15.729
1.080 10.541 15.876
1.090 10.638 16.023
1.100 10.736 16.170
1.110 10.834 16.317
1.120 10.931 16.464
1.130 11.029 16.611
1.140 11.126 16.758
1.150 11.224 16.905
1.160 11.322 17.052
1.170 11.419 17.199
1.180 11.517 17.346
1.190 11.614 17.493
1.200 11.712 17.640
On The Tree
Joined: Nov 2013
Posts: 193
Likes: 0
From: Waterford, MI
so, you view the AFR on the E85 scale, would the difference be that most gas gauges on AFR like my AEM I belive stops at about 10.0 or 9.5 or so, so it really wouldnt be able to accuratly use the gauge and would just have to view the data and gauge would pretty much be useless?
On The Tree
Joined: Nov 2013
Posts: 193
Likes: 0
From: Waterford, MI
i guess I have a hard time wrapping my head around this I know its been discussed multiple times, I have yet to actually get hands on experience with it. the wideband I know reports lambada so in theroy your gauge would report gas AFRs? and you just tune as if its gas? 14.7 is really 9.760 but it just reports 14.7 because the lambada is the same at different AFR? probably overthinking this LOL
Thread Starter
Joined: Jun 2009
Posts: 363
Likes: 1
From: San Antonio, TX
so, you view the AFR on the E85 scale, would the difference be that most gas gauges on AFR like my AEM I belive stops at about 10.0 or 9.5 or so, so it really wouldnt be able to accuratly use the gauge and would just have to view the data and gauge would pretty much be useless?
It is just a different unit of measurement. Think of it like this, you have a tape measure that is imperial on one side, and metric on the other. You measure out a foot, it reads 12" on one side of the tape, and 30.5cm on the other side. Same distance, just a different form of measurement. Want to make it really simple? Keep it and tune it on the gas scale.
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Let's say you are doing for peak power N/A. This is roughly 12.7-13.0 with Gas. With E85 this is 8.5 to 8.7. On a WB that is setup for gas you are still aiming for 12.7-13.0 even though your true AFR is 8.7.
In lambda is 8.7 to 8.9. Your O2 setup measures 8.7-8.9. It is converted to gas afr. It doesn't matter what fuel you run. It's still roughly the same lambda.
The point is that if you keep a gas WB....your peak N/A targer will stay ~12.8 no matter what fuel you use. The E85 will simply take ~30% more IDC to get you to that AFR.
In lambda is 8.7 to 8.9. Your O2 setup measures 8.7-8.9. It is converted to gas afr. It doesn't matter what fuel you run. It's still roughly the same lambda.
The point is that if you keep a gas WB....your peak N/A targer will stay ~12.8 no matter what fuel you use. The E85 will simply take ~30% more IDC to get you to that AFR.
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Verdad Gallardo Thread Starter
Joined: Jun 2009
Posts: 363
Likes: 1
From: San Antonio, TX
ah it makes since to me now. thanx guys. so basically im looking for the same afr number as if it was gas. i just use the chart listed above to know my acual e85 ratio, right? i think i got it. I appreciate all the help guys!
Pretty much. You'll just be using a lot mroe fuel to attain the same AFR. One thing you can try is:
If your tune is spot on with normal gas and the stoich setting in the OS is at 14.6 try to change it to 9.76 when you add the E85. See how close your tune is still. Your WB will still be reading 14.6 for shoich(1.0lambda). If the gas you put in is really E85 then you should be pretty dang close to stoich.
The Flex cars have a sensor that changes this field for you(assuming supporting OS). Granted there are other things like timing.
If your tune is spot on with normal gas and the stoich setting in the OS is at 14.6 try to change it to 9.76 when you add the E85. See how close your tune is still. Your WB will still be reading 14.6 for shoich(1.0lambda). If the gas you put in is really E85 then you should be pretty dang close to stoich.
The Flex cars have a sensor that changes this field for you(assuming supporting OS). Granted there are other things like timing.
