Hello,

I recently rebuilt my 4.6 dohc (Supercharged Vortech) and was told to purchase the 30# injectors for better performance. The engine had the 19# injectors install prior to the rebuilding of the engine and NOW it is running to rich in fuel. I was told that i would have to Dyno and have to reprogram the ECU in order to make it work correctly. Does anyone have any experience or any recommendation for the this particular situation? Please help!

 

Have you had it on the dyno, to get an A/F?
Many times when you go to larger injectors you will have to lower fuel pressure or use some sort of chip or tuner to adjust. The issue is you, have gone to larger injectors (holes) with the same fuel pressure and the computer is firing the injectors at the same rate as before, so you end up with more fuel at idle than before. You now have more fuel but the need for more fuel is not there at idle.
I suggest first get on the Dyno, check the A/F at WOT, adjust fuel pressure to get ~11.8:1 and see what idle conditions are. If still rich, you will need chip or tuner.

Last thing, the 30#s might not be big enough for the HP you are making, do you know how much you are making? If the injectors are too small, it will cause you to jack fuel pressure up, which will cause the down low rich issue.

 

Your lucky your car is running at all. I would go with 42 lbs injectors, bigger fuel pump and boost assist. You have to have your chip set up for it, because it won't run for crap if you don't.