I tried switching a dpfi motor to mpfi unsecessfully. I am turning it back to dpfi, and the first crank it ran poorly on two cylinders then died. I have been messing with the ecu. now the main relay is buzzing and I checked the ecu fuse, and it's fine. my main question is what else would make that relay buzzz?

 

bump, is it always a bad ground?

 

yea try checking all grounds...when mine was buzzing it was the thermostat ground on top of the thermostat. alls i did was tighten one bolt up and my b16 fired right up. not sure if its the same with your setup but def check for loose/missing grounds. good luck...