300zx rough idle



My 1992 Nissan 300zx has had a tolerable rough idle for some time. Until recently the missing was not present when driving at speed. I took it into a shop and after a complete tuneup, new air filters, fuel injector service, cleaning corroded connectors to the injectors and replacing one bad injector the rough idle remained. The mechanic said he could not identify the cause and recommended I take the car to a Z specialist. The nearest one is 50 miles away. My mechanic thought the problem might lie in the EFI wiring harness.

Any assistance would be greatly appreciated.


I’d agree with your mechanic. The ECU harness is tend to get damaged by the heat. Also, a bad ignitor could cause the symptom.

For the record, replacing the harness is going to be a labor extensive job. Good luck.