BOSCH INJECTION TOOLD KDEP 1541 LDA Positioning Device 0 986 612 053

The KDEP 1541 is inextricably linked to the LDA (Ladedruckabhängiger Volllastanschlag), or Manifold Pressure Compensator. In turbocharged diesel engines, the mass of air entering the cylinders varies drastically between idle (low boost) and full load (high boost). A mechanical fuel pump, without an LDA, injects fuel based on throttle position. If the operator commands full throttle at low RPM before the turbocharger has spooled up, the pump injects a "full load" volume of fuel into an engine starved of air. The result is incomplete combustion, manifested as dense black smoke (opacity) and high exhaust gas temperatures (EGT).

The LDA solves this by mechanically limiting the travel of the fuel rack (control rod) based on boost pressure. A diaphragm senses manifold pressure and pushes a vertical rod downwards. This rod has a conical profile (a taper). A tracing pin connected to the fuel rack rides on this cone. As boost rises, the cone moves, allowing the pin to extend further, which in turn allows the fuel rack to open wider.