Originally Posted by t vago
It would be instructive to know what all is hooked up, and where is it hooked up with, with regard to an E85 kit. Does the E85 kit require a setup procedure?
I suspect the only things that really get hooked up are power, ground, and the injector connections themselves. I also suspect that there's a lack of any meaningful setup procedure. If this is the case, then I suspect that the E85 kit only lengthens fuel injector pulses by some set amount. And if that's the case, then there's no reason why you could not just use larger flowing fuel injectors, instead.
You are correct about the connections; it's just injectors (female on one side, male on the other) and a ground. The overhead in the units appears to be taken care of by using the DC offset of the injector channels.
The two kits I've had did have trim adjustment, and said they had a "Cold start assist" feature which I have to assume is just a fat enrichment bias when cold or when first started. Unfortunately both cars are long gone so I can't take another look at them for temperature sensors or timing IC's or other clues to their possible nonlinear behavior.
Obviously the benefit of having a magic box kit is that there's something to sell ("Buy our box!" is a lot more marketable than "Buy new injectors for your car, we've figured out which ones you need!") and it's a lot easier to install, literally just clip the wires in place. No mess, no cutting and completely reversible. If they sold larger injectors in a kit that actually requires a bit of aptitude, bleeding off fuel pressure and removing the fuel rail(s), and for example on my wife's car that would also involve removing the upper intake manifold which itself requires disassembly of a few throttle and emissions related bits.
Still, if the box isn't necessary it's not necessary.
For Science I've bought a set of 27lb injectors for my Escape, it ships with 24lb injectors. I've also been keeping an eye on LTFT and fuel pressure histograms in FORSCAN to see if the factory bits are in a good place to be shifted. So far it looks like fuel delivery (from the pump)is adequate at WOT on-ramp pulls and there's generous room for de-enrichment in the fuel trim maps