FAILURE DIAGNOSTIC DEVICE OF FUEL INJECTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a failure diagnostic device which can be completed in a common rail system and can diagnose failure of a fuel pressure sensor even when a fuel injection valve fails.SOLUTION: A failure diagnostic device (50) applied to a fuel injection system (10) having a pressure accumulating chamber (20), a plurality of fuel injection valves (40) and a fuel pressure sensor (22) includes injection execution means for executing fuel injection on a predetermined injection condition with remaining fuel injection valves when fuel injection is executed by one fuel injection valve on the predetermined injection condition, detected drop amount calculating means for calculating a drop amount of a fuel pressure in the pressure accumulating chamber as a detected drop amount, estimated drop amount calculating means for calculating an estimated drop amount of the fuel pressure in the pressure accumulating chamber as an estimated drop amount, fluctuation calculating means for calculating fluctuation in the detected drop amount, and fuel pressure sensor failure determination means for determining failure of the fuel pressure sensor when the fluctuation is within a first prescribed range and the difference between the detected drop amount and the estimated drop amount is outside a second prescribed range.SELECTED DRAWING: Figure 2