So I replaced the Ignition Switch and that wasnt it. Thought it was since I drove a day without a hiccup, but by day 2 the problem came back.
As a next troubleshooting step, I have a Bluetooth ODB scanner and the “Torque” Android app, so i got the idea to plug it in and turn on logging and have it log a data file while I drove and experienced the cutout. It logs stuff like speed, rpm, voltage, sensor data, etc of the car every 1/10 of a second. So I started driving, and I noticed that when it cuts out, the Bluetooth ODB scanner loses connection and has to reconnect. So the logs arent helpful since the ODB scanner loses power when it happens. But the fact that the scanner loses power for that split second during the cutout is very good troubleshooting information I think! I think this means that the ECU itself is losing power, which is why the ODB scanner loses power, since the ODB connection is what powers the Bluetooth scanner. This tells me one of two things. Either the ECU itself has some type of issue, or it seems there is a bad connection to the ECU. I say this because I dont lose power anywhere else when this happens (radio, headlights, dash) and normally the bluetooth ODB scanner has power when plugged into the ECU even if the car is turned off with no keys in the ignition. In other words power is always going to the ECU, and power is always going to the ECU’s ODB port. But when the cutout happens, it seems that power goes away for a half second. Bad ECU? Loose connection maybe? Wiggling the harness and any wires under the steering column doesnt replicate it. I will say that about a month or two before this started happening, the voltage regulator on my alternator went bad and was actually putting out too much voltage to the car. I got a check engine light and looked up the code online and it said something like “Voltage exceeded 17 volts for more than 3 seconds”. So then i tested with my multimeter and it was 16.8 which is higher than the 13.5-14.5 range it should have been in. So I put in a new alternator and that fixed it. So one possibility I’m thinking is that the high voltage could have damaged something in the ECU, though I’m not really convinced of that. But still contemplating getting a used one off ebay just to see what happens.
So I think this must be an electrical issue and has to do with the ECU or power to the ECU. As i think I said in my first post, I’ve already tried swapping the ECU relays and fuses, so its not that. Also, what about an internal short in the battery. Possibly? But wouldnt the power to the other components be lost in that split second as well? I had considered the battery, since the high voltage can ruin a battery, but it has been working just fine, as in cranking just fine ever since the ordeal with the alternator.
Any thoughts?