<正>论述了基于模糊数学理论的汽车发动机异响模糊诊断方法，提出了模糊诊断数学模型、模糊关系矩阵的建立方法及模糊推理诊断过程。据此建立的汽车故障诊断专家系统，提高了对发动机异响故障诊断的准确性和可信度。

It is difficult to diagnose automobile engine’s abnormal sound breakdown because it is fuzzy. For diagnosing the breakdown rapidly and accurately, this paper deals with the fuzzy diagnosis method on automobile engines abormal sound based on the fuzzy mathmatic theory and puts forward mathmatic modeling of fuzzy diagnosis, method of building fuzzy relation rectangular array and diagnosis processing of fuzzy reasoning. By applying these techniques, the automobile breakdown diagnosis expert system has high accuracy and reliability on diagnosing engines abnormal sound. It has been proved in the process of repairing on some types of automobile engines. 