Computerized Engine Controls: Notes

The 900S, 9000S and all Turbo models are equipped with the Bosch LH Jetronic system. LH Jetronic uses an air mass meter to determine air density, altitude, and temperature. These measurements are then sent to the fuel injection system ECU.

The Bosch LH-Jetronic fuel injection system integrates the fuel injection and idle speed control functions into one system. Fuel injection system Electronic Control Unit (ECU) controls system functions.

The LH-Jetronic fuel injection system operates with moderate fuel pressure, held constant by a line pressure regulator. Fuel is metered into the cylinders by electrically controlled solenoid valves in the injectors. The injectors are installed just ahead of each cylinder intake valve.

Actual duration of injection (2-12 milliseconds), is determined by the ECU. The ECU receives several signals on various driving, engine and outside conditions from a set of sensors and an air mass meter. Signals from air mass meter and exhaust gas oxygen sensor provide most of the information used by the ECU to maintain proper air/fuel ratios. An idle speed adjustment screw is located on throttle housing.