. "Alternatively, or in addition, a combination of feedback information and other information can be used to estimate WF. For example, one can use the airflow (e.g., from the MAF sensor) and air/fuel ratio (e.g. from an exhaust sensor) to determine a total amount of fuel provided by the injectors, and then use the injector slopes and offsets to determine an amount and ratio of water in the water/etha" . . .