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故障现象一辆2007年产名爵MG7车,搭载18N4T1发动机,因连续多日下雨,车内有积水,到修理厂清理积水,并更换车内地毯,处理结束后,发动机无法起动着机。故障诊断与排除起初维修人员以为电路连接处有积水,造成漏电,或者导线连接器端子生锈后接触不良,但仔细对电路进行排查,未见异常。经进一步检查,发现在起动时火花塞跳火正常,但喷油器不工作。检查喷油器的电源,正常,由此推断发动机控制单元没有向喷油器发出喷油控制信号。把相关搭铁线处理一遍后试车,故障依旧。由于没有专用的故障检测仪,无法读取故障代码与发动机数据流(一般的故障检测仪无法与该车发动机控制单元通讯),故障诊断陷入僵局。
Symptoms A 2007 MG MG7 car, equipped with 18N4T1 engine, due to continuous rains, the car has water, to the repair shop to clean water, and replace the car carpet, the treatment is completed, the engine can not start the machine . Fault diagnosis and troubleshooting At first, maintenance personnel think there is water in the circuit connection, resulting in leakage, or poor contact after the wire connector terminal rusty, but careful investigation of the circuit, no exception. Upon further examination, it was found that spark plug sparks normally at startup, but the injector does not work. Check the injector power, normal, infer that the engine control unit did not issue injection control signal to the injector. After the relevant grounding line test again, the fault still. Failure to read the fault codes and engine data flow without a dedicated fault detector (the general fault detector can not communicate with the vehicle engine control unit), the troubleshooting deadlock.