Computers and Control Systems: Description and Operation

The Bosch LH-Jetronic fuel injection system, used on 928 and 928 S4 models, uses an air flow meter incorporating a filament (hot wire sensor), various sensors and an Electronic Control Module (ECM) to control fuel injection. The measurement of the air mass is performed by the air flow meter with the filament sensor, which measures the air upstream of the intake manifold. This provides exact measurement of the quantity of oxygen being induced through the air flow meter, allowing the ECU to determine the exact amount of fuel required for efficient combustion.
An electric fuel pump draws fuel from the fuel tank, creating pressure within the system. Fuel system pulsations are controlled by a pressure damper, while pressure in the fuel system is controlled by a pressure regulator.