Yes. In fact we talked about this quite awhile ago, when the FiTech units were starting to take off.
This has benefited all TBI style EFI setups, but they really took off when FiTech released theirs at less than half the price of everyone else's on the market at the time. So it became more and more pronounced that you needed an additional grounding bond.
Does not have to be a large battery cable size affair. Just a 10ga wire or pre-made strap.
It could probably even be 12, or even 14 gauge in size, but 10g seems to be a nice way to go and can carry way more current than anything in the EFI system is ever going to generate. But hey, dissipating RFI might be better accomplished with larger wire. I don't know, but I'm sure others here know what would be best.
The issue is too much gunk between the TBI and the main battery ground. A more positive ground reduces noise, or at least it's effect on things, as well as just plain letting the computer know more of what's going on.
None of that is technical knowledge on my part of course. Just a simple way of saying it makes it feel better.
So the standard practice is to add a wire, or one of those store-bought braided straps under one of the TBI attaching nuts to the point on the intake manifold that you have mounted your engine ground to the firewall.
You have in fact added a grounding strap between the intake and the firewall. Correct?
With computer controlled systems in old vehicles, the mantra is "grounds, grounds, and more grounds" because there is no such thing as overkill.
Sure, you can add more than you need. But doing so won't hurt anything.
So, this is how it must go on a Bronco:
1. Good ground from battery to engine.
2. Good ground from battery to body (in at least one place).
3. Good ground connection between the engine and the body (usually at the back of the intake).
4. Good ground between the engine and the frame.
5. Good ground between the body and the frame. (not as common, but can't hurt).
6. And if you're feeling particularly modern and up-to-date, add a ground strap between the main body and the hood.
Not because the hood can't ground through all that metal contact it's got at the hinge, but because after 50 years of rust, paint, gunk and other corrosion methods, it might not be very good anymore. Just like the grille and rest of the front clip are not very well grounded to the tub because of potential rust on the spot welds where the skirts attach to the tub.
And a hood is a huge potential noise maker/reflector/transmitter I would think.
I guess we haven't touched on it in awhile, but it was all we were talking about last year.
So yeah, grounds, grounds, and more grounds.
Paul