What is Lambda?

Can anyone explain to me in simple terms what Lambda is?

A lambda of 1.00 is stoich for the fuel combination you're running. It is independant of air/fuel ratio. Lambda is what a O2 sensor measures natively. Air/fuel ratio is derived from lambda using a formula based on the type or composition of the fuel, such as the percentage of alcohol.

Lambda is a nickname for a particular thing, which Mark already described.

Sort of like Pi is a nickname for the relationship between radius and circumference of a circle. Makes it easier to discuss than if you always had to say "3.14159265358979". (And yes, I have it memorized to that many decimal places.)

lambda = (actual A/F divided by theoretical A/F) where theoretical A/F is different depending on which fuel you use.

Example, lets say your A/F on the dyno read 12.5 and stoich. A/F for gasoline is 14.7, your lambda will be (12.5/14.7) = .85

Thanks! That pretty much explains simply what Lambda is. Generally speaking, where should your Lambda be at during regular driving/WOT?

Can anyone explain to me in simple terms what Lambda is?A nickname? Some will say lambda is stoich, or refer to lambda as stoich. That is not correct.
Simply put, Lambda is the percentage of a given fuel's stoichiometric #.

... where should your Lambda be at during regular driving/WOT?With the formula provided by RQ, experiment with the math. Regular driving? You know what CL stoich is. For max output you may have also seen the 12.5-13.0 #s. From GM the #s are closer to 11.0-11.5.

A nickname? Some will say lambda is stoich, or refer to lambda as stoich. That is not correct.
Simply put, Lambda is the percentage of a given fuel's stoichiometric #.


Sorry, but a lambda of 1.00 is stoich for the fuel that you're using. AFR is derived from lambda using your fuel combinations formula.

A nickname? Some will say lambda is stoich, or refer to lambda as stoich. That is not correct.
Simply put, Lambda is the percentage of a given fuel's stoichiometric #.

With the formula provided by RQ, experiment with the math. Regular driving? You know what CL stoich is. For max output you may have also seen the 12.5-13.0 #s. From GM the #s are closer to 11.0-11.5.

Gary,

Could you post your car in you signature or a little bit about your experience. I can't understand your "nebulus" answers to peoples simple questions.:)

Sorry, but a lambda of 1.00 is stoich for the fuel that you're using.Did I say it wasn't. What did I post? Lambda is a %. Lambda of 1.0 is 100% of stoich, BTW. A lambda of .75 is 75% of stoich. How could this be misunderstand? Again, lambda is a percentage of stoich. Test time; what AFR would be 1.09 lambda, when stoich is 14.7? In this case, 1.09 is 109% of 1.0. 1 divided by 1 is 1. 1 is a 'whole' number. The 'whole' pie is 100% of it. 109% of the pie is a little more. This is your basic 3rd grade math. :)

Test time; what AFR would be 1.09 lambda, when stoich is 14.7? In this case, 1.09 is 109% of 1.0. 1 divided by 1 is 1. 1 is a 'whole' number. The 'whole' pie is 100% of it. 109% of the pie is a little more. This is your basic 3rd grade math. :)

I dont really understand your answer based upon how I thought you were asking the question...

If my lambda is 1.09 and stoich A/F is 14.7, then my actual measured A/F is 16.02 right? Not sure what your 1 divided by 1 is all about...maybe you were asking something else.

16.02/14.7 = 1.09

Some will say lambda is stoich, or refer to lambda as stoich. That is not correct.


That is what you posted. Lambda is stoich. Lambda = 1.

If you refer to a percentage of Lambda, such as .90 or 90% or 1.05 or 105% then you're talking about about how far you are away from stoich.

My 3rd grade class never discussed lambda, stoich or percentages of Lambda or AFR, so I'm just catching up. Please bear with me. (I don't mean take your clothes off so settle down)

Mark, my reference to 3rd grad math was in regards to figuring percentages, not to figuring the AFR. Now you're being silly (or sarcastic). :) I 'spose we are sorta saying the same thing. Lambda 1.0 IS stoich, as you pointed out. I acknowledge that, as Lambda is using stoich as it's reference point. When you say lambda is stoich, you are implying the (1.0) as a given in that statement. Is that the correct way of stating it? I believe that is what our disagreement centers around. My use of the word did not imply the 1.0, as a lambda value in regards to AFR, will not always be 1.0. The lambda # (value) you see on the screen, will be a % of stoich. If you happen to see 1.0 on the screen, you have 100% of stoich.

According to a web source, the definition of lambda;
The value of lambda is the ratio of the optimal use of each input to its actual usage.
I used the word [percentage], which IS a ratio.

Edit: There are more important things in life to disagree on.