Speed Density
Speed density is the most popular fuel control system employed but rusEFI users are present. This is due to its simplicity of tuning and it's suitability for turbocharged cars.
It is due to this widespread use that it is the most well developed fuel control method and is the primary recommendation for fuel control at present (27/4/2020).
Speed Density is probably the most popular algorithm since with knowing MAP calibration, CLT, IAT and TPS and injector flow rate we get a good enough tune without much difficulty.
fuel_squirt_duration = injector_lag_curve_lookup(V_BATT) + warm_up_curve_lookup(COOLANT_TEMPERATURE) * (cylinder_displacement * VE_table_lookup(RPM, MAP) * MAP / GAS_R * charge_temp(COOLANT_TEMPERATURE, INTAKE_AIR_TEMP, TPS)) / target_afr_table_lookup(RPM, MAP) / injector_flow
where:
MAP is the average of multiple 10KHz ADC readings within specified camshaft angle range, value in kPa
VE is intake volumetric efficiency coefficient
GAS_R is gas constant
charge_temp is charge temperature heuristic formula: Tcharge = CLT * (1 - Tcharge_coff) + IAT * Tcharge_coff Where Tcharge_coff is interpolated between 0.25 if RPMs are low or throttle is closed to 0.9 if RPMs are high and wide open throttle. See http://rusefi.com/math/t_charge.html
The Speed density strategy in rusEFI shares its basic tuning method with all other speed density systems in other aftermarket ECUs.
If you are familiar with the tuning of another aftermarket ECU then it is likely the tuning of speed density on rusEFI will be very easy to get into.
