I have a simulation of a fuel injection system and the result is a set of pulses that operate the injectors. I know how long the pulses are in milliseconds and I know how much fuel is emitted from a single injector per millisecond. Therefore I know the fuel consumption. I also know the manifold vacuum.

Is it possible to calculate from this information and perhaps published engine specifications how rich or lean the fuel mixture is, e.g. the air-fuel ratio (AFR)?

This is an old, simple engine that doesn't have variable timing or anything fancy at all and only very minimal emissions control. No computer control.

Can anyone give a general overview that can help with my research?

  • $\begingroup$ its possible, but not easy. the flow through an engine cylinder is complex. That's why modern fuel injected cars use mass air flow sensors to do the work for them. $\endgroup$
    – Tiger Guy
    Oct 18, 2022 at 22:44
  • $\begingroup$ @TigerGuy Ah - that is what I feared - many thanks. $\endgroup$
    – user150402
    Oct 19, 2022 at 5:20
  • $\begingroup$ So volumetric efficiency of a normally aspirated engine is below 100% even around 70% while a turbocharged engine most often can exceed 100%. $\endgroup$
    – Solar Mike
    Oct 19, 2022 at 7:03


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