When it was running I'd cycle the key and could hear relays clicking but I don't hear them now. I'm not sure if Lars told you but the car is a jdm rhd miata.

 

you can't power the unit up that way... the ms would technically provide 5v to the serial ports...

 

My mistake, it wasn't working with it in the car so I figured I'd try unplugging everything and trying it on my bench. I'm just at a complete loss for ideas as for what to try to get it to work reliably.

 

the only thing that I could think that would cause this is an intermittent short somewhere -- so the MS protects itself and you can't connect/run, or a loose power connection.

when the car wont start and you cant connect to the ecu with the to key ON, are you getting 12v to ECU (tan/red wire on your harness) or the injectors? It's run off the Main Relay which is behind the FUEL INJ fuse -- basically everything on the white/red power wire in the car (injectors, fuel pump, solenoids).

 

I didn't check on the tan/red wire in the car harness, will have to check that later today as I'm working and car is at home, but the 12v switched wire that is soldered with the tan/red in the jumper harness gets 12v with key on

 

basically, that's the same wire. if the car dies/wont start & MS wont connect while still keyon, but you have 12v on that wire, then the problem is happening within the MS itself.

 

Is there a way I can tear into it on my own and see what the issue is, or do I have to send it back to you/Lars?

 

I just had some starting problems yesterday, uping my WUE fixed it. TUNE the car, play with settings (do research before you break something) but play with things and learn, it will serve you so so good in the long run.

 

It's an ecu issue not a tune issue it was just a coincidence that it started after trying so many times.