Cold starting control

Cold starting control

Under cold starting conditions the following occur:

• natural impoverishment of the mixture (due to poor swirl of the fuel particles at low temperature)
• low fuel evaporation
• condensation of the fuel on the inner walls of the intake manifold
• higher viscosity of the lubricating oil.

The control unit detects this condition and corrects the injection time on the basis of the:

• coolant fluid temperature
• intake air temperature
• battery voltage
• engine rpm.

The spark advance depends only on the rpm and on the engine coolant fluid temperature.

During starting the control unit commands a first, simultaneous injection for all the injectors (full-group injection) and, after detecting the stroke of the cylinders, it starts normal, timed, sequential operation.

During the engine warming phase, the control unit governs the idle speed actuator to adjust the amount of air needed to ensure the engine self-supporting speed.

The rotation speed is decreased proportionately with the increasing engine temperature until obtaining the nominal rating when the engine reaches normal operating temperature.

Combustion control - lambda sensor

With the engine in the following conditions:

• idle speed
• medium load
• temperature > 30°C

with a special integrator, the control unit processes the lambda sensor signal and determines the injector opening time.

Timing variator control and modular intake manifold

To optimise the amount of air taken in by the engine, the control unit controls:

• intake timing on two angular positions
• the geometry of the intake manifolds on two lengths.

At maximum torque the control unit sets the “open” phase:

• cam advanced by 25° of the engine
• intake box long manifolds.

At full power the control unit sets the “closed” phase:

• cam in normal position
• intake box short manifolds.