In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Markistuff,

When you developed your equation for mass flow and the engine RPM cancelled out, then something went wrong.  Without engine speed your Speed-Density system degrades to just a Density system. 

MFR air = Density * (Volume flow Rate) * VE

Density= MAP/(R*T)   where: MAP = manifold absolute pressure

                                            R=gas constant

                                            T = inet air temperature

Volume Flow Rate =Displacement * RPM

Therefore:

MFR air = (Disp * RPM * MAP)/(K *T) * VE    where: K=const to make the units work 

MFR fuel = MFR air/(A/F)

for most fuels and MAP levels 75% of max MAP you can run stoichiometric ie. 14.6 lbm air/1 lbm fuel and stay closed loop with the O2 sensor.  Beyond that you shoud be in open loop and run richer 12.5:1 is fine.  I do not know what kind of engine you are using be generally a lean A/F at high speed and load will result in a piston with a large hole in it.

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