General description

GENERAL DESCRIPTION

The Bosch Motronic ME2.1 driven throttle system a belongs to the category of integrated electronic sequential, phased ignition and injection systems. The ECU controls the idling ratio air intake by means of the electronic throttle. The ECU controls spark advance to adjust the engine to changes in environmental parameters and applied loads. The ECU controls and manages injection so that the stoichiometric ratio (air-to-fuel ratio) is constantly optimal. Essentially, the main functions of the system are:

• self-learning;
• system self-adapting;
• self-test;
• Alfa Romeo CODE (Immobilizer) ECU acknowledgement;
• cold start control;
• fuel-lambda sensor control;
• knock control;
• acceleration enrichment control;
• fuel cut-off upon accelerator pedal release;
• fuel vapour recovery;
• engine rpm limitation;
• fuel pump control;
• connection to climate control system;
• cylinder position acknowledgement;
• optional cylinder injection time control;
• spark advance;
• idling ratio management (also according to battery voltage);
• fan control;
• connection to instrument panel.

INJECTION SYSTEM

The essential conditions which should always be fulfilled in preparing the air-to-fuel mixture for the good operation of controlled ignition engines are mainly:

• "metering": the air-to-fuel ratio should be kept as close as possible to the stoichiometric value to ensure maximum catalytic converter efficiency.
• the mixture should be homogenous, i.e. consist of petrol diffused as finely and uniformly as possible.

IGNITION SYSTEM

The ignition system is the static advance induced discharge type (i.e. without high voltage distributor) with power modules inside the injection ECU. The system has a single coil for each spark plug (MONOCOIL).

The advantages of this solution are:

• less electrical overload;
• guarantee of constant discharge at each spark plug.

A map containing the entire set of optimal spark advance values (for each cylinder at power stroke) which the engine can adopt according to the ratio and the engine load is stored in the ECU. The ECU corrects spark advance mainly according to:

• air coolant temperature
• air intake temperature
• knock.

The information that the ECU processes to pilot the monocoils is received in the form of electrical signals emitted by:

• air flow meter and temperature sensor, for the exact quantity of intake air
• rpm sensor which produces an alternating single phase signal indicating the engine rpm
• knock sensors (on the upper part of the crankcase between the two heads) to acknowledge the cylinder where detonation is occurring and to correct spark advance
• throttle potentiometer to acknowledge load conditions (idling, partial and full)
• phase sensor.

The information processed by the ECU for controlling optimal metering is received in the form of electrical signals emitted by the:

• air flow meter and temperature sensor, for the exact quantity of intake air
• rpm sensor which produces an alternating single phase signal indicating the engine rpm
• throttle potentiometer, to acknowledge the required accelerator conditions
• coolant temperature sensor on the thermostat
• lambda sensor to determine the oxygen content in exhaust gases.