Car will only start if i leave my EFIlive cable hooked up! As soon as the cable is removed and i attempt to start the car nothing happens, all the lights on the gauge cluster will light up but nada, turn the key back to off, plug my EFIlive cable back into the OBD port and voila car starts and runs perfectly fine again...

Car is a 1999 Camaro SS.

 

Fixed! Turned out to be a problem with G110, so i snipped the wire at S110 and redid the ground right to the battery so i dont have to deal with that ground behind the head anymore!

 

Glad you found it... thanks for posting your result.