My wideband lowest AFR value is 10. I believe I need to change the wideband to read Lambda.
I have hptuners and wondering how to set a custom pid to read lambda?

 

What wideband do you have. My Innovate has a setup screen, you can chose gasoline, diesel, propane, natural gas, ect. I havent setup one for reading e85 though.

 

i have a PLX wideband.

 

I may get hounded for this but just tune it using the regular afr numbers. I went through this time and time again with users on here and hptuners about an eq ratio for E85. My brother is a professional car tuner for import cars toyota, honda, mitsubishi etc ans uses E85 very often He told me just to tune the car on E85 with my wideband as you would with gas. I wasn't sure so I had my tuner set up a custom pid to convert the numbers for E85. Well when we put my car on my brothers dyno he hooked his wideband up along with mine as well! He was absolutely right when I was seeing a lambda reading at WOT of about .78 on my wideband he was seeing 11.4 on his with the regular gas settings! The only reason you need to have a cutom pid is so you can log your afr error % correctly because as I'm sure you know the stoichiometric value is changed on E85!

 

i thought WOT on e85 would be in 6.9 to 8.5 range for AFR

 

Widebands don't read AFR they read LAMBDA. While 1.0LA = 14.63AFR for Gas. 1.0LA = 9.75 for E85. What that means is that the AFR displayed on a Wideband spitting out Gas AFR figures are actually richer when on E85. ie 14.63 = 9.75. Just rescale your PIDS to fix it for error logging.. Or just work in LA full time.

 

Thanks, I understand that.
I guess I wasn't clear enough on my question.
My wideband only goes as low at 10, so if my AFR for E85 is supposed to be 9.75 my gauge won't go that low.
What are you E85 users doing to read you AFR that low?
My wideband is a PLX.

 

Just leave it set as gas, it will read just fine.

You will see 14.7 on your wideband when actual is 9.75.

You will see 12.0 when your actual is 8.0, get it. Just tune like you are using gas still.

 

Even more complicating is the fact that E85 may not be E85, E85 means it has a MINIMUM of 15% gas in it. Most E85 around here in CO is actually E80. Ive also found most cars I tune for E85 end up being around 11:1 in reality. I dont bother adjusting/calculating AFR, I just use 14.7:1 as lambda, whether its corn juice or dino juice.

 

I also use a PLX wideband. it does not matter what number your PLX meter shows. The signal it gives when interfaced with HP Tuners is just a 0 - 5 volt ouput based on Lamda. So, at Lamda, regardless of what fuel you are using, it tells HP Tuners it is getting a reading of 2.35 volts. Examples: on gasoline at ~14.7 afr, PLX sends a 2.35 volt output to HP Tuners; on E85 at ~9.7 afr, PLX sends exactly the same 2.35 volt output to HP Tuners. Your only concern is how far above or below Lamda you are or want to be, and that is being interpreted properly. The fact that the reading on your PLX gauge is based on a gasoline calibration, while you are burning E85 (or any other fuel), is irrelevent.

 

Now I get it. Thanks very much for your inputs.

 

I found this on another forum. It's helped me get full understanding to finish my e85 tune.
"Understanding Air/Fuel ratios
This article assumes you already understand the concept of the air/fuel ratio (AFR), but if not, familiarize yourself by visiting this Wikipedia link. You may have already read that E85 has a different stoichometric air fuel ratio than gasoline's 14.7. The stoich AFR for E85 (at 85% Ethanol) is 9.76. The stoich value represents an ideal perfect burn of the fuel usually used at part throttle conditions. Full throttle conditions require a richer mixture than stoich to prevent the dreaded detonation, or pinging.

However most AFR gauges you can purchase to display a numerical value of the AFR, are showing you values for gasoline. This is where it can get tricky, and it's important to understand how this ratio works on both gasoline and ethanol-based fuel.

All AFR's regardless of fuel type work off of a common number called Lambda. A value of 1.0 in Lambda represents the stoich for any fuel. Gasoline is Lambda 1.0 at stoich. E85 is Lambda 1.0 at stoich.

If you already have a standard gasoline AFR meter hooked to a wideband O2 sensor, you can still use the displayed gasoline AFRs in determining your engine's true AFR. For example, if your gasoline meter is showing 14.7, then we know this is Lamda of 1.0. The equivelent on the E85 side is around 9.7. Therefore you can conclude that the 14.7 you see on the gauge is a true AFR of 9.7. This allows you to effectively use existing gasoline AFR components or software to tune an E85 Mustang without buying special equipment. Simply use the same target AFRs on your gasoline gauge that you normally targeted for gasolline. "

 

For the people who want the short answer-

when using E85 - ( and if its actually E85 not less ) then divide the number you see on your wideband by ruffly 1.5

Wideband gauge-/ 1.5 = estimated AFR E85
14.7------------ / 1.5 = 9.7
12.0 ----------- / 1.5 = 8.0

My motor car likes more than 8.0 WOT so I see 11.5 or 7.6 -

There are other ways to set the gauge to read Lambda and ways to make HPtuners read the E85 AFR while logging and all that- But there isn't a real reason to that I see.