Joined: Nov 2016
If you change your injector size, your computer can't tell. It only knows "I'm supposed to squirt THIS LONG under THESE CONDITIONS".
Its sensors will read 'rich' or 'lean', if the tune's not right, so it can try to adjust a little - but you're getting another whammy because the higher alcohol content doesn't always read the same on O2 sensors.
So basically, changing your injectors without a tune means that your computer is going to be putting in a random amount of fuel, and then based on sensor readings, making random adjustments.
It might run. It might even be close! But personally, since you're looking at the possibility of suffering catastrophic engine damage if the fuel curve is enough out of whack, I think you'd be a lot smarter to wait for the tune. Not worth risking your DD because of impatience.
I smile a lot. It makes people wonder what I'm up to...