Warm-Up Enrichment Control
System Diagram
System Diagram
After the starting mixture enrichment control and the post-start enrichment control, air-fuel mixture continues being adjusted to the rich side by the warm-up enrichment control. Further increase in temperature evaporates fuel still-condensed on the piston sliding surface.
ECM calculates the injection time of the warm-up enrichment control according to the following sensors and signals.
- Intake camshaft position sensor (Intake camshaft position)
- Exhaust camshaft position sensor (Exhaust camshaft position)
- Engine coolant temperature sensor
- Charge air temperature sensor upstream of throttle valve
- Charge air temperature sensor downstream of throttle valve
- Pressure sensor downstream of throttle valve (Engine load)
- Crankshaft position sensor (Engine speeds, crankshaft position)
ECM extends fuel injection time for injecting more fuel according to the characteristics map. At this time, ignition timing is controlled according to the dedicated characteristics map. ECM allows exhaust gas to flow from the exhaust valve to the combustion chamber by controlling the intake camshaft actuator and the exhaust camshaft actuator for performing valve overlap. Accordingly, hot exhaust gas heats up the combustion chamber, and fuel evaporation is accelerated. This reduces increasing amount of fuel.
In the range of idle speed, fuel injection time is influenced mainly by coolant temperature at a startup. During low/medium load, fuel injection time is influenced by engine load.
At the completion of the cold starting mixture enrichment control, the control is switched to the air-fuel ratio control to adjust fuel injection time.