Hi!
Objective: Dissecting Autotune to use universally.

* Convert an AFR difference (i.e. -1.5, if target=13.5 and O2=12) into a percentage.
* Apply the percentage to an existing fuel cell value.

Here's my current formula (I know, it's wrong)...

y - (-0.1x)(-1y) (Based on 10 increments from 10-20 AFR)
x = AFR difference
y = fuel value


i.e. 300-(-10%)(-300) = 330
x = -1
y = 300


Any suggestions?

 

Wait, what? Explain what you're trying to do again.

 

This.

Hmmmm, I know what you're looking for kinda. Explain your thought process with your original equation a little bit, and why you came up with that.

 

I am not sure why you would need a "slope" equation. It is just a percent difference.

For example.

target is 13.0 and actual is 15.0 and fuel cell value is 400.

15.0 / 13.0 = 1.15 (+ 15%)

400 * 1.15 = 460

Target is 13.0 and actual is 12.0 fuel cell value is 400.

12.0 / 13.0 = .92 (- 8%)

400 * .92 = 369

So the equation is

(Actual / Target) * current fuel value = New Fuel value

I am pretty sure that is right, but who knows it is too early for me.

 

this is correct...actual/target is your fuel value multiplier. works for afr and lambda...

 

And equivalence ratio which is just 1/Lambda

Seriously I hate engine research. Who came up with equivalence ratio?

 

Great responses, thanks! Okay I'll explain in case you have any additional input.

This is an excel worksheet, part of an educational project.
Table 1 = Target AFR's.
Table 2 = Imported AFR's.
Table 3 = Existing fuel values.
Table 4 = Export fuel values.

For the areas I have no AFR data for ("=0"), how can I condition those cells to avoid a "0" output?

 

IF( [Measured AFR] > 0, [Current Fuel Value] * [Measured AFR] / [Target AFR], [Current Fuel Value])

This will keep the existing fuel value if you don't have a measured AFR for that cell.

 

that is bad ***. thanks a million Mr. Norris.
PS, Texas Ranger sucked, but your martial arts competitions were magical.