Fuel Delivery and Air Induction: Description and Operation

The Jetronic fuel injection system is designed to adjust the amount of fuel needed to the effective engine requirements in all RPM ranges. This intermittent low pressure fuel injection system is controlled essentially by the amount of air drawn in by the engine and the RPM. To determine the proper air/fuel mixture, the Electronic Control Unit (ECU) analyzes data from the air flow sensor, [1][2]engine temperature sensor, ignition electronic control unit (IECU), microswitch, altitude sensor, oxygen sensor and thermocontact. The ECU analyzes this data and sends electrical pulses to the injectors, which are activated by electromagnets and operate simultaneously, thus atomizing the fuel upstream of the intake valve.

To ensure proper fuel distribution, two injections are delivered for each engine cycle. Half of the amount of fuel metered for each engine cycle is atomized at each injection. This system, together with the oxygen sensor, constantly measures an optimum fuel mixture while reducing the amount of pollutants in the exhaust gases.