I have a MSpnpPro in my 01 Miata. I am running the ECU as it came from DIY but with a few modifications in regards to what inputs are used for various functions.

None of the modifications SHOULD have anything to do with any of my issues.

The specific problem I am having is that while cranking I lose all communication between my ECU and laptop. It reconnects once the engine starts.

Is this normal? If not, what could be happening?

I am guessing that I should be able to stay connected while cranking because otherwise how would I pull a cranking log if I was troubleshooting that?

I did notice the other day that when the battery voltage got down to about 11 volts I did not have enough power to start the car. The battery is only at most only two and a half years old.

Thanks!

 

What is your voltage while cranking? Might be getting too low.

 

I'll have to try and meter it when I get home tonight.

Joe Perez seems to think that they ECU doesn't know the engine is cranking, (a separate but possibly related issue.)

He came by to buy some wheels from me and while here is asked him to look at my startup settings. It went downhill from there... lol.

The more I think about it the more I think my battery is just toast. I'll see what Good-Win says about the warranty.

 

Put it on jumpers and try and crank it.

 

low voltage