Probable causes of ECU Blowing

[Ash108]

Hey peeps!
Just want to get to the bottom of an issue with my ecu thats happend for the 2nd time.

After fresh engine build,new wiring harness from COZ and Nistune via Emulation seems like my ecu has popped somewhere along the spark/ignition side of things- spark on 4 cylinders only-

Iv done the following:

Tested 2 working S2 PTUs
Tested my CAS- On 2 Cars
Tested coilpacks.
New Spark plugs
Checked Earth on motor.
Bridged Ignition Relay in Engine bay and only got 4 cylinders firing.

Took my ecu to a friend and tested it on his car,did exactly what its doing on mine,only firing on 4 pots,hooked his ecu back in and ran fine.

So just want pointers on probable causes of how this can happen to the ecu.

[solaire]

Is the ECU losing spark or fuel on those 2 cylinders? I haven't seen many issues on earlier model nissans but on the newer quest they'll get bad coils that blow the ECM. Even on chrysler if you get a bad injector or coil it can back feed into the ECU and blow the driver circuit. Could be a place to start looking.

[nissanfreak12]

When you said you replaced the harness, which one? You have the alternator harness and the body harness which also ties into the ECU. It sounds like a short in the older harness causing the issues you are having, it's not normal for an ECU to blow like that, unless you are just having bad luck. I know it is not COZ's tuning, I have one from him with zero issues for years

Have you checked what the alternator is putting out voltage wise?