calculating afr

[AccordFan_18]

does anyone know if there is an equation for calculating afr using certain variables like;

rpm
TPS
injector duty
temperature
stoichiometric(14.7)
air density

or any others

any info would be cool

[evil_demon_01]

You can't really a calculate it (in closed loop)
If you could there would be no need to have the o2 sensor.

[GhostAccord]

It would be much easier just to get yourself a wideband O2 sensor and guage.

[HondaBob]

Technically you could calculate what your engine should do if you knew ALL the variables like the exact BSFC and volumetric efficency of your setup. There is more to it however that is way too in depth for me... It's much easier to just put the car on the dyno with a wideband, and tune your car. It gets the job done, right, without having to do a stupid amount of math.

In turn, i'm sure you could find more info on line if your trying to do a school project or something. Try looking on megasquirt forums or something. they usually use that kind of stuff to home build a basemap from scratch.

[wed3k]

http://www.jaysautoservice.com/Software.htm

you need a 5 gas anylyzer or pay a place a couple bucks to pull a run. i use my buddies dyno/gas anylyzer at his smog station all the time for diagnostics.