Engine control unit using speed density conversion
The present invention utilizes a speed density method for determining the cylinder air mass using volumetric efficiency (VE) based on engine speed and manifold pressure. The VE data contain the cylinder filling efficiency for various engine speed and manifold pressure values. The manifold pressure is then measured by a manifold absolution pressure (MAP) sensor. Using the speed density has the advantage that it is much less affected by pulsation in the intake system of the vehicle, and does not require a linear air flow past a sensor in the engine intake system.
1. A method for injecting fuel into an engine comprising:
providing an engine control unit;
modifying the engine control unit to evaluate fuel injection duration using two methods in situ;
providing an air flow meter;
measuring air flow using the air flow meter;
calculating cylinder air mass using the engine speed;
providing a manifold air pressure (MAP) sensor;
measuring a manifold pressure using the MAP sensor;
storing in the memory of the engine control unit volumetric efficiency values for each load and speed value;
determining a fuel injection duration by the engine control unit using the measured mass flow and determining a new fuel injection duration determined by the engine control unit using the volumetric efficiency at the given load and speed value;
selecting a fuel injector duration using the given load and speed value using volumetric efficiency if determines it the engine control unit determines that it is preferable to the fuel injection duration using the air flow measurement;
applying an air temperature compensation;
injecting fuel into a combustion chamber for the selected fuel injection duration; and
returning the injector duration control using the mass flow meter measurement.
2. The method of claim 1 further comprising an air mass versus injection duration table for determining injection duration using the mass flow sensor.
3. The method of claim 1 further comprising means for adjusting the instructions based on one of the group comprising closed loop, cold enrichment, and acceleration enrichment.