ECU Master TUNER3 Service Manual download pdf (Page 34)

Speed Density algorithm

In Speed Density algorithm the injector opening time is calculated based on a physical model using absolute

pressure in the manifold, volumetric efficiency of the engine under given load, engine speed and the temperature

of the intake air that affects its density.

Volumetric efficiency table is a parameter that is subject to modifications during the engines tuning and is

defined on the VE Table map. The basic formula used to calculate the time of opening the injectors (in ms) looks

the following way:

PW = INJ_CONST * VE(map,rpm) * MAP * AirDensity,

where:

PW (Pulse width) – is the time of opening the injectors in ms

INJ_CONST – It is a constant dependent on the engine’s capacity, size of the injectors and the Injection Divider

parameter, it represents the time of opening the injectors in order to receive stechiometric mixture by 100%

engines volumetric efficiency, 100Kpa pressure and 21C temperature.

VE(map, rpm) – Is the value from volumetric engine’s efficiency table in percent.

MAP (Manifold absolute pressure) – absolute pressure in the manifold,

Air Density – Percentage difference of air density against air density in temperature 21C.

Additionally the time of opening the injectors is based on corrections and enrichments. Due to that fact the total

formula for calculating the injector’s opening time looks the following way:

PW = INJ_CONST * VE(map,rpm) * MAP * AirDensity * Baro * Warmup * ASE * EGOCorr * AccEnrich +

InjOpeningTime,

where:

Baro(Barometric correction) – correction of absolute pressure against barometric pressure

Warmup(Warmup enrichment) – value of enrichment of the mixture in the function of cooling liquid temperature

ASE(Afterstart enrichment) – current value of Afterstart enrichment in %

EGOCorr(Exhaust gas oxgen sensor correction) - correction value of the fuel dose based on the narrowband

lambda sensor in percent.

AccErich(Acceleration enrichment) - current value of in acceleration enrichment described in %.

InjOpeningTime (Injectors opening time) – injectors dead time in ms, corrected by the voltage value of the car’s

electric installation.

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ECU Master TUNER3 Service Manual Page 34