Method and system for engine control

摘要

Methods and systems are provided for controlling exhaust emissions by adjusting an injection profile for fuel injected into an engine cylinder from a plurality of fuel injectors during engine start and crank. By splitting injection of fuel during start so that a portion of fuel is port injected and a remaining portion is direct injected as one or multiple injections, the soot load of the engine can be reduced and fuel economy can be improved. The injections are adjusted based on the alcohol content of the injected fuel to take advantage of the charge cooling properties of the fuel.

主权项

1. A method of operating an engine, comprising,
during a first cylinder combustion event since engine start, port injecting a first amount of fuel during a closed intake valve of the first cylinder combustion event; direct injecting a second amount of fuel over multiple injections of the first cylinder combustion event, the first and second amounts based on an alcohol content of the injected fuel; and continuing the port injecting and direct injecting of the fuel for a threshold number of cylinder combustion events since the first cylinder combustion event, the threshold number based on the alcohol content of the injected fuel, the threshold number increased as the alcohol content of the injected fuel increases.