Norm Peterson

Unless you know something about the duty cycle of your existing injectors, blindly throwing larger ones at the car isn't necessarily the answer either. You'll lose resolution in the lower rpm ranges, and injectors aren't at their best at 1.0 millisecond pulse widths to begin with.


Norm

blueherd02gt

So my tune was worthless? I don't get why you posted this...

PROMETHEUS PRIME

You can use stock injectors but if you got the duty cyle at almost 100% you're running the risk of having run stick open. Larger injectors will have a lower duty cycle and will help eliminate this risk.

Scotte28516

Your tune wasn't worthless at all. 60# injectors are not at all necessary for the boost you're running, which is most likely exactly what I have, 10psi. You absolutely did not need that big of an injector for that![&:]He was merely saying that you went overboard beyond what was ever necessary. You didn't do anything wrong, but you didn't do anything that was needed, either.

Norm Peterson

"Overboard" is a good description regarding the injectors. And it's not the tune, at least not directly.

What I was getting at is that 60# injectors are so large for 4.6 liters worth of engine that you may very well end up with idle that's not entirely stable and give up some low speed/light throttle behavior. I don't see any point in making that kind of sacrifice if you aren't requiring at least 75% duty cycle from the larger injectors (given that the OE's would be completely inadequate). Pulse widths from the PCM aren't going to change from incrementing in 0.10 ms steps to 0.05 ms steps just because you installed injectors that have twice the flow. And if your OE injectors were working at 1.5 ms at idle, figure that the 60's would need to be down around 0.75 ms, which is below the level at which the operation of these things ends up in consistent fueling.


Norm