Ignition:

the control unit controls the injectors at great speed and with great precision, calculating the opening times on the basis of engine loading (r.p.m. and air delivery) also taking battery voltage and engine temperature into account.

Injection is simultaneous; all the injectors are opened at the same time during each revolution permitting the cylinders to be supplied with the correct amount of fuel and improving operation during the transient states.

Ignition:

ignition is of the static type and is controlled directly by the control unit which regulates the advance on the basis of engine loading (r.p.m. and air flow).

For information regarding the static ignition system, reference should be made to GROUP 05.

Control of cold starting:

during the cold starting phase, the control unit uses the advance and injection time values.

During starting the control unit also controls the injection at each ignition impulse and not at each revolution of the crankshaft as happens during normal operation. When a certain temperature/engine r.p.m. ratio is reached, the control unit returns the system to normal operation.

Control of enrichment during acceleration:

upon acceleration the control unit increases injection in order to reach the required loading as quickly as possible.

This function is carried out by the potentiometer located on the throttle valve which instantaneously alerts the the control unit that maximum power has been requested, anticipating the signal coming from the air flow meter which shows a great increase in air flow and in this way an immediate response is obtained.

Fuel cut-off during deceleration:

with the throttle valve closed and the number of revolutions exceeding a threshold value (approx. 1200 r.p.m.), the control unit interrupts fuel injection; in this way the number of revolutions decreases rapidly towards idle speed and fuel consumption, controlled to a greater degree, is as a consequence, greatly decreased. The threshold value of the cut varies in relation to the temperature of the engine.

Control of idle speed:

the regulation of idle speed is carried out through an actuator which acts on the by-pass of the throttle valve. This acts as an additional air chamber and as a regulator for the operation of the various functions (e.g. air conditioning compressor): with the throttle valve at the stop limit the actuator regulates the by-pass clearance compensating for the power requested by the functions in order to guarantee an idle speed which is as far as possible constant around prescribed value.

The actuator employed in this version guarantees high speed regulation as the opening and closing of the by-pass are both closed by magnetic windings. Idle speed adjustment, for small variations, is already carried out by the ignition advance after which it is regulated by the by-pass.

NOTE: The automatic adaptation function of the system makes it possible to avoid regulating the idle r.p.m. which recognizes the "throttle valve in the stop limit position" by way of the throttle valve potentiometer, making it possible to "trace" any wearing which may influence the closed position of the throttle valve.

Limitation of maximum r.p.m.:

once a certain threshold has been exceeded (around 6400 r.p.m.) the control unit automatically interrupts the fuel injection in order to avoid overloading the engine and to protect it when the revs are excessively high.