NGK AFX wideband and E85

[shitstang]

Trying to get an e85 tune setup and ran into a problem. The car starts but runs horrible and all my ve error numbers are very positive (tried adjusting in realtime with no change). The stoich is changed to 9.8 but I never changed the settings for the wideband in my input. My question is if I change the numbers to volts/1.067+6.054 will that allow me to use the gas VE error histogram, right now I have it as volts/0.714+9? If not what will allow me to use the VE error histogram? I know tuning in lambda is easier but the wife drives it too and its easier if its in AFR, for her anyway.

[SMOKINV8]

Unless the NGK is different, it'll read 14.7 at the stoich ratio even on E85.

[98Camarod]

I know if you have the correct transfer function in the pid it will log it in the e85 afr. I'm trying make sure that mine is correct, but no one is responding to my thread either.

[racerx203]

I know if you have the correct transfer function in the pid it will log it in the e85 afr. I'm trying make sure that mine is correct, but no one is responding to my thread either.

All i can tell is e-85 takes alot more fuel to use so ve error sounds right addd more fuel.

[shitstang]

I left the transfer function for e85 the same as gas and just changed stoich to 9.8, well after starting the wideband would read 9.8 but at cruising would be mid to high 11s. The car actually runs better in the 11s (probably because I'm trying for 11.6 on a gas scale). My fuel trims are around 25 so I would copy and paste into realtime and the car would run like complete shit so I would undo and it would run (not great but run). It seems like the wideband is reading opposite of what it should and I'm wondering if I need to change the transfer function for the correct trims and I have no idea why the wideband is reading 9.8 because all I changed was stoich.

[jim2092]

Talked to NGK yesterday (877 473-6767) and one of their techs told me that their AFX will not read E85 accurately without a correction factor.

[DSteck]

It has worked fine on E85 for me. I don't bother with AFR though... Just work off of lambda, and your life will be easier.

[jim2092]

It has worked fine on E85 for me. I don't bother with AFR though... Just work off of lambda, and your life will be easier.

So when you set up your AFX to work in Lambda, what are the Lambda values for 0 v and 5 v? And how are they calculated?

[DSteck]

0.62 and 1.1 for 0 and 5 volts, respectively.

[jim2092]

So what you are saying in brief is that the AFX is always going to show the same voltage when the fuel you are burning is burning at IT'S stoichimetric level as long as that level is between the limits of the AFX (0 and 5 volts which is .62 - 1.1 lambda and 9.0 and 16.0 AFR for reference). And that any variance from that voltage (rich or lean) will be accurately reported as a lambda value above or below 1.0 and can be used as a mutiplier in the VE/MAF tables to correct the fuel imbalance as needed. Values above 1.0 calling for more fuel and below 1.0 calling for less fuel from the ECM. And that programming the HP software with these voltages instead of AFR will eliminate the confusion caused by use of different fuels having different stoichimetric values.

And lastly that in the case of the AFX, that stoichimetric voltage is set for regular gas which makes the controller AFR reading only accurate for pure gas.

[DSteck]

Yes.

That's how any wideband works.

[sarg]

Love the screen name. That is what I call my little 89 hatch that I bought for $500. It has been the best $500 I ever spent on a car. It is not pretty, but it hauls crap around well and keeps on going.

[jim2092]

I have been told that my summary above is NOT correct and has two mistakes.
1. different fuels burning at their stoichimetric level are doing so at different voltage readings NOT the same voltage.
2. The AFX is NOT limited to just reporting the correct AFR for the fuel that it is set for (regular gas). It will report the correct AFR for every fuel that falls within its reporting parameters (9.0-16.0 AFR).

Comments?

[sarg]

I was under the impression that if it was at stoich it would display the same voltage no matter the fuel, hence the preference of many to just use lambda.

[DSteck]

I have been told that my summary above is NOT correct and has two mistakes.
1. different fuels burning at their stoichimetric level are doing so at different voltage readings NOT the same voltage.
2. The AFX is NOT limited to just reporting the correct AFR for the fuel that it is set for (regular gas). It will report the correct AFR for every fuel that falls within its reporting parameters (9.0-16.0 AFR).

Comments?

Wrong and wrong. Stoich is stoich is stoich. Lambda is lambda is lambda.

Stop thinking about AFR. EVERY wideband reads lambda and converts it to AFR.

[seevi]

Wideband O2 sensors actually measure the amount of residual oxygen (for lean mixes) or unburnt hydrocarbons (for rich mixtures) in the exhaust gas and report that value as a voltage to the sensors controller. Lambda is the ratio of actual AFR to stoichiometry for a given fuel mixture. Because the composition of common fuels (gasoline, E-blended gasoline, methanol, diesel fuel, propane) varies, and because many modern vehicles can handle different fuels, when tuning, it makes more sense to talk about lambda values rather than AFR.

A wideband sensor by itself doesn't know what kind of fuel it is measuring and therefore doesn't know what it's lambda value is.

[DSteck]

Wideband O2 sensors actually measure the amount of residual oxygen (for lean mixes) or unburnt hydrocarbons (for rich mixtures) in the exhaust gas and report that value as a voltage to the sensors controller. Lambda is the ratio of actual AFR to stoichiometry for a given fuel mixture. Because the composition of common fuels (gasoline, E-blended gasoline, methanol, diesel fuel, propane) varies, and because many modern vehicles can handle different fuels, when tuning, it makes more sense to talk about lambda values rather than AFR.

A wideband sensor by itself doesn't know what kind of fuel it is measuring and therefore doesn't know what it's lambda value is.

I think I love you.

[LSxpwrdZ]

Whoever started the afr trend needs to be shot!

Do yourself a favor and forget AFR. Learn Lambda!

[Iam Broke]

Whoever started the afr trend needs to be shot!

Do yourself a favor and forget AFR. Learn Lambda!

^^^ X 1000!

[jim2092]

I understand using lambda error to tune the VE/MAF cells but isn't your commanded lambda created by dividing by the stoich AFR value of the fuel you are using?