Fuel Injection System - BOSCH LH: Description: Notes

The Bosch LH-Jetronic fuel injection system integrates the fuel injection and idle speed control functions into one system. One Electronic Control Unit (ECU) controls all 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. See Fig 1 .

Fig 1: Cutaway of Air Mass Meter

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Signals from air mass meter and exhaust gas oxygen sensor provide most of the information used by the electronic control unit to maintain proper air/fuel ratios. An idle speed adjustment screw is located on throttle housing.