Is it possible to start the car with the main switch off? If so, what's the switch for? Besides if the FiTech isn't getting power, you won't be starting your car.

Connect it to the battery one way or another. Add a junction block connected to the battery that is always hot while the battery is grounded. My FiTech is connected to a one wire alternator on the same post that is connected directly to my battery. I've disconnected my battery many times and reconnected it with everything hooked up. No problems. The FiTech has some form of parameter ram, and saves the settings you've entered. You won't lose the settings. I've probably done some other odd ball stuff and not fired anything.

 

No car can not start with the switch off but my thought was that if it is in the off position and you accidently turn the key to the start position that it could flow power through the EFI in the wrong direction and possible damage the electronics.

I basically made the same connections as you did to keep the efi Whith power at all times.

 

You could interrupt the tach signal wire with a switch and do the same thing I would think.

 

Although this may not fly with some NHRA techs I recommend always putting the MAIN BATTERY power that powers the "ECU" directly to "posts" on the battery. ALL other EFI power should be after the cutoff switch such as switched ignition, and if possible, the power for the injectors and for sure all ignition.

The car will shut off with the battery disconnect. The battery is the best "filter" for the ECU.

I also DON'T then run "dirty" power and grounds directly to the battery.

The only negative is this still leaves live power wires in the car with the disconnect shut off.

 

Doug, when you say filter you mean the battery will absorb spikes and dips vs coming off say the horn relay or back of the alt which will see a electric fan come on with the massive inrush current.