most ecms work like this
1. you have an airflow measurement, either with a MAF or speed density (a volumetric efficiency map, in other words a chart that says 'in this condition the engine flows this much air')
2. you have the fuel flow metrics, that end up calculating something like 'if you open the injector for this long, this much fuel comes out'
3. you then try to hit your AFR target vs airflow vs injector metrics to figure out how much fuel to inject
this is both in open loop and closed loop.
there are auxiliary calculations like closed loop trims, transitional fuel needs like accel enrichment, and some other small calculations and constants, but those modify things in the above three steps. without step three, you aren't going anywhere.
in other words, without step three, how would you know that you don't inject one part air for one part fuel?
Bookmarks