I had the same problem. From what I remember, I was not getting constant power to the coils. Make sure that after "cranking" there is still power going to the coils while the key is in the "on" position.

 

what's the reason/code?

 

Not a ECU problem, but a body/engine wiring harness problem. Check your wiring from the column to the motor. Coils should be getting constant power with ignition and after iginition.

 

I have the same problem. I have swapped a supercharged 6.0 into a 68 camaro. The motor starts runs for about 4 or 5 seconds then dies. after I have tried for a few times And the motor is warm I can hold the throttle about half and when the motor starts it still dies but if I continue to hold the throttle it will pick back up run for a few and do the same. It will continue to do that I definitely I have sent the computer back to blackbear performance twice and they say they have disabled the VATS I have tried two different harnesses and checked the grounds numerous times. I have bypassed the harness for the fuel pump and the power for the ECU. Still does the same

 

Do you have the mass air flow sensor on it? Even though I had changed to speed density I still had to run the mass air flow sensor to get mine to run for more than a few seconds.

 

That's completely wrong. That means you didn't have it failed properly.

 

Did you figure this out? What did it end up being? I have almost the exact issue now. TIA

 

Same damn problem what's the solution?

 

my tune was for 80lbs injectors but I had 60lbs injectors. Fixed that and it ran great.

 

Same problem, starts 3 sec dies suddenly. I do Have a red light on my fuse box goes away when engine starts and comes back after engine dies.
No codes