Lambda

As you stated in your video, tuning with lambda 1.00 mixture is always stoichiometric. The way you explained lambda is very simple and seems user friendly to understand. My question is if the 1.00 is stoich when working with lambda, how does the gauge sensor on a typical wide band o2 sensor know when the vehicle was to switch fuels for example from gasoline/petrol to e85? Will that setting be made at the ecu or the gauge controller?

I'm not quite sure what you're asking?

a/ as far as the "lambda" value is, that's a fixed datum - ie, it makes no difference what the fuel is, because it's the oxygen in the gas that's being measured.

b/ as far as "AFR" gauges are concerned, a very few may have an option to set for a different fuel, but if it's a petrol/gasoline calibrated gauge it doesn't, and cannot, change the DISPLAYED AFR value to what is correct for a different fuel. An Exx blend may have a true AFR of, say, 10.5:1 at lambda 1.0, but will still be displayed as 14.7:1.

c/ for those reasons, especially when an Exx fuel is used that may have a range of actual alcohol content, it's much easier to use lambda, which is consistent, rather than AFR which will be variable.

If you have a different query, please add a comment explaining it?

Jonathan is asking about lambda gauge readings with different types of fuel. The thing is that O2 wide band sensor doesn't care what fuel you are using since it's measuring residual oxygen in exhaust gases and then translates it to lambda value. What figure it will show on the gauge depends on the dash used- if that's for gasoline it will show 14.7 (or lambda 1), if that's for ethanol it will show 9.6 ( still lambda 1), if it's for methanol it will show 6.5 (still lambda 1) etc...

Georg1970 is on the right track. So what I’m asking is are AFR gauges that we typically see like for example a aem wide band o2, designed to read gasoline/petrol ? Or is the AFR reading just a scale and it’s up to the tuner to understand what values are stoichiometric on each fuel that they use?

Gord based on what you said above, if I switched fuels on a gauge calibrated for gasoline and petrol, it will still display 14.7 as stoich even if the actual stoich reading would be 9.0:1 for example using ethanol. Am I correct on this thought?

What you see on the gauge is interpretation of lambda value related to particular fuel. That is why advanced tuners alwsys use lambda on the gauge instead of afr...

Yes, if the gauge is set in petrol scale AFR it will just interpret lambda based on that scale, you will often see people discussing flex fuel tuning in equivalent petrol AFR scale but as Shota said describing lambda removes any confusion.

Yes, the gauge reads the lambda value and displays what the gasoline AFR is that corresponds to that lambda number.

Some gauges have a switch to change between "gas" AFR and lambda value displays.

Even if you're currently stuck with the 'gas" AFRs, you can use a conversion chart* for different fuels - lower than 14.7 will be 'richer, higher leaner, regardless, compared to lambda.

* For example