| 摘要 |
PROBLEM TO BE SOLVED: To provide a diagnostic method and a diagnostic system for an engine having a variable valve mechanism, wherein the operation of a variable valve mechanism is directly evaluated in a production process of an engine to contribute to an improvement in the shipment quality of the engine. SOLUTION: The system comprises: rotational drive means 2 which rotates the engine 1 having a variable valve mechanism; pressure sensors 3-1 to 3-4 which measure the intake pressure (pressure within an intake port) of the engine 1; and arithmetic and control means 7 which controls the rotation of the engine 1 by the rotational drive means 2, provides the variable valve mechanism with a cam switching instruction to switch a cam, and decides the operation of the variable valve mechanism on the basis of outputs of the pressure sensors 3-1 to 3-4 before and after the cam switching instruction. With rotating the engine 1 at a predetermined number of revolutions, the intake pressure of the engine 1 before and after the cam switching instruction is measured, and the operation of the variable valve mechanism is decided on the basis of measured pressure waveforms before and after the cam switching instruction. COPYRIGHT: (C)2005,JPO&NCIPI
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