When doing an E10 tune should the stoich afr be set to 14.137 in hp tuners?

[desertg8]

In AZ all we have is E10 unless you run race gas or E85. So with hp tuners should not the stoich afr be set to 14.137? When I had a dyno tune it was set to the standard 14.67822 and a pe enrichment ratio of 1.18. But at wot I think the computer knows it is E10. Maybe that is why when the tuner commanded a 12.5 afr we were getting a 12.8 to 12.9 afr. You would need to command a 11.9 to 12.0 afr with e10 to get he 12.5 ratio. In my case a 1.22 pe enrichment ratio.

I know you need to tune your maf first. The question is not on the maf tuning.

[G8-4-Speed]

Looks like you need to add a little gain to your MAF to get it to match your PE. Then richen up your PE to get 12.0.

[G8-4-Speed]

Check your running AFR before trying to change it. Mine likes to run around 14.5 since it was new and it took adjusting the close loop proportial fueling to get anything else. For whatever reason, the tune wont remove any fuel after 14.67, even if you command 15.3. If your is running a little rich already, I would say leave it unless your having running issues with it that way.

[0352Goat]

If you weren't seeing what was being commanded your MAF/VE tables were not correct, keep working.

As for the AFR question.. You only have to change your stoich AFR to reflect what you're runing, be it E10, E15 or whatever. Everything else is just a calculation based off your stoich, and falls in line. If you're running E10 fuel the PE AFR of 12.8ish ( what you should be around any ways with a stoich of 14.7 ) is too lean. I left mine at 1.145 when I switched to constant E10 fuel, which gave me a 12.83 with a stoich of 14.7. With E10 I am at (WB verified) 12.40 and have made the most power using the older proper PE Ratio. If I had incorrectly chose to keep the general 12.8 AFR for WOT it would have been a 1.109, but as I said before a 12.8 is too lean for E10 fuel. Leave it around 1.145

..Eh, make sense?

[0352Goat]

Also, my stoich is 14.2.

[desertg8]

14.2/1.145 = 12.4. got it.

[bluegoat06]

PE should not be changed from the tune in an effort to seek the magic 12.8afr number. PE doesn't change just because you're pumping E10, E70 or E85. Granted, E10 has a different max best power rich/lean lambda coefficient than E85 or straight gas.

Generally speaking,
max best power lean for E0 is .90 lambda,
max best power rich is .85 lambda

for E85 .90 lambda is too lean,
max best power lambda for E85 is around .86 lambda
max best power rich for E85 is around .78 lambda

How you translate all of this ? first, forget thinking about afr, it adds a lot of confusion when you start tuning for oxigenated fuels. the reason is simple, most WB's come pre-set to display Lambda X 14.7 or the equivalent of lambda x stoich.

Life was good when stoich was 14.7, add E10 with a 14.11 stoich, or E85 with a 9.85 stoich, and you'll go crazy thinking you need to modify PE to lean or richen things up. in close loop, the WB would always display 14.7 regardless of the fuel of choice, why, cause it's displaying lambda x 14.7
Stoich lambda for any gas is 1.0, afr stoich is different though, so if you pump E85, and the engine is running in CL, don't expect WB to display 9.85 as it should, it'll display 14.7afr.
At WOT, the WB is displaying Lambda X 14.7, so if you're shooting for a PE of 1.145, your lambda is actually 1/1.145 or 0.87 lambda, the WB would display 0.87x14.7=12.8 AFR.

Now, pump E10, the actual stoich point for pure E10 is 14.11, your PE is still 1.145, your lambda is still 0.87, but the WB would display 0.87 X 14.7 (12.8afr) when it should display 0.87x14.11 (12.2afr), the inmediate thought, PE should now be 1.156 to command a 12.2afr. and this is where the confusion starts, not couting the fact that if you fuel was spot on, she also lean out 4%, you don't correct for that 4% with PE, you correct for that 4% in the stoich afr cell in the calibration.

Easiest formula : Lambda=1/PE, PE=1/lambda
Set PE to shoot for .85 lambda on E10 or E0 or E85, it won't matter what kind of fuel you have, PE would be equal to 1.174 or 1/0.85
Only thing you need to do is tell the pcm the correct stoich point (in AFR) for the gas she's burning, and forget about AFR displays on the WB. set the WB to display lambda and make your life easier. leave PE the way it is for E0 and E10, adjust PE on E85 to find the best lambda where the car makes the most power, some N/A cars like to run at .80lambda, some others seem to like .85, probably because the content of alchol on E85 differs a lot from gas station to gas station. your fuel trims would always let you know how far are you from the actual stoich at part throttle since they read what?? Lambda

Embrace the lambda concept, and only think AFR when you're modifying the afr stoich cell in the calibration. it can't be easier....really.

[bluegoat06]

Btw, 14.11 would be correct afr stoich point for pure E10.
the problem is, might have 10% ethanol is different from being pure 10% ethanol. the difference is only 4%, so some people will just split the differece between 14.11 and 14.68, and use 14.4 instead in the afr calibration. let the fuel trims take care of the rest, shoot for .85 lambda at WOT (PE=1/lambda or 1/0.85 in this case), and call it a day.

[desertg8]

i was doing some googles and i think the 14.4 for e10 is as close as you can get the stoich set. most e10 gasoline were anywhere from 5-8 percent alcohol. i guess that is why the pumps state they they may contain up to 10 percent ethanal.

setting the pe to 1.1765 would get you the .85 lambda.

i noticed though running the pe at say 1.16 for up to 4400 rpm provided a little crisper acceleration. that might be because of volumetric efficiency being lower and the need for more gasoline is not needed at the lower rpms.

my car has peak torque at 4800 rpm. So I set my stoich to 14.4 and my pe from 0-4400 rpm at 1.16 and from there on up it is at 1.1765.

I am calling it a day on that calibration.

Now we go to the maf calibration. I need to learn how to log. I am used to the editor. But not the scanner.

My maf frequency was set kind of high from my tuner. But I am running without a screen on the stock maf and he correctly knew that for the given air flow hitting the sensor I was getting more air in than a screened maf.

Bluegoat I looked at your maf settings and actually di a hybrid tune with your maf settings. Do not worry. I will not blame you if my car blows up. I then did a test drive and it felt good.

So the next time at the track I am going to try two different tunes.

And I know I have to install my wideband and learn how to use the scanner.

[desertg8]

questions on street tuning a maf without a wideband with hp tuners.

assuming I know how to use the scanner to pull up ltft and stft how would i go about it?

i think you want to shoot for a -2 to a plus 2 with ltfts and in open loop with stfts the same number.

positve number means you are running lean and on wot it will add fuel.

negative number means you are running rich and on wot it will delete fuel. that is on the ltfts.

so would you tune with the ltfts? or stfts?

also do you start with the stock maf settings and in increments blanket all the cells? if you did each one individually it would take for ever.