A method and system 10 for reducing cold-start emissions of an automotive
vehicle 12 having an internal combustion engine 26. System 10 includes a
main controller or control system 14, a variable valve timing system 16,
an ignition system 18, a fuel metering system 20, and vehicle operating
condition sensors 22. Controller 14 detects cold-start conditions based on
signals received from sensors 22, and in response to such a detection,
controller 14 generates command signals to said variable valve timing
system 16, to said ignition system 18, and to said fuel metering system
20, effective to respectively alter valve timing, spark timing, and said
air/fuel delivery of engine 26 in a manner which synergistically increases
air/fuel enleanment limits, improves combustion characteristics, and
increases exhaust gas temperature, thereby reducing cold-start emissions.