A method for detecting an injector solenoid fully open time comprising: detecting a slope inflection in a derivative of a current draw of the injector solenoid using a filter, thereby detecting a fully open time of a direct injector solenoid; wherein a data collection window begins after a delay period has elapsed, which is a minimum solenoid opening time; measuring a current draw by the injector solenoid during said data collection window; determining an opening time detection window within said data collection window; and calculating a derivative of the measured current within the opening time detection window, thereby determining a derivative data set; filtering the derivative data set within the opening time detection window, and thereby magnifying each of said possible slope inflections; and comparing each of said magnified possible slope inflections to a threshold and identifying an actual slope inflection occurrence where a magnified possible slope inflection crosses said threshold; the method being characterized in that a median window and a mean window are further defined within the derivative data set, wherein the median window and the mean window are synchronized sliding windows and wherein the mean window is encompassed by the median window; and wherein the derivative data set is processed successively through two filters: a slope inflection filter and a slope discrimination filter; wherein an output of the slope inflection filter for a given data point in the derivative data set is defined by the relationship: Outinflection = mid ∗ dfact − mean ∗ gfact where Outinflection is the output value of the slope inflection filter, mid is the center value of data points in a derivative data set median window centered on the data point sorted in ascending order, mean is a mean value of data points in a derivative data set mean window centered on the data point, and dfact and gfact are determined by the following relationships: gfact = 1 + ABS mid − mean dfact = 1 − ABS mid − mean where ABS is the absolute value function. determining an opening time detection window within said data collection window; and calculating a derivative of the measured current within the opening time detection window, thereby determining a derivative data set; filtering the derivative data set within the opening time detection window, and thereby magnifying each of said possible slope inflections; and comparing each of said magnified possible slope inflections to a threshold and identifying an actual slope inflection occurrence where a magnified possible slope inflection crosses said threshold; the method being characterized in that a median window and a mean window are further defined within the derivative data set, wherein the median window and the mean window are synchronized sliding windows and wherein the mean window is encompassed by the median window; and wherein the derivative data set is processed successively through two filters: a slope inflection filter and a slope discrimination filter; wherein an output of the slope inflection filter for a given data point in the derivative data set is defined by the relationship: Outinflection = mid ∗ dfact − mean ∗ gfact where Outinflection is the output value of the slope inflection filter, mid is the center value of data points in a derivative data set median window centered on the data point sorted in ascending order, mean is a mean value of data points in a derivative data set mean window centered on the data point, and dfact and gfact are determined by the following relationships: gfact = 1 + ABS mid − mean dfact = 1 − ABS mid − mean where ABS is the absolute value function.