[Diy_efi] P&H vs. sat (was: Diy_efi Digest, Vol 21, Issue 1)

[Adam Wade]

--- ScottyGrover at aol.com wrote:

> Peak-and-hold injectors (at least the ones I have
> had dealings with) ran in series electrically with
> resistors which increased the resistance and lowered
 
> the required current in the circuit so as not to
> increase the drain on the power transistors in the
> control box.

I am so used to thinking in sequential port injection
that I often forget about batch and bank fire
applications.  You can certainly run several
low-impedance injectors in series to allow triggering
of a bank-fire setup with only one "channel" per bank,
thus lowering the cost and heat output of the ECU (I
don't think anyone does this any more in production
vehicles, but it is entirely possible that it was done
on the Jag back in the day, offering the option of
using the stock injectors in a P&H setup with a
sequential fire ECU that would allow a lot of engine
modification without having to upgrade the injectors
themselves).

You can get the same effect by running several
high-impedance injectors in parallel, and then wiring
up such groups serially, so the resistance across the
whole chain is the same as in a single high-impedance
injector; the more injectors you add like that,
though, the more sluggish the individual injectors
will be (since voltage is being split up between the
parallel groups of injectors); I wonder if using caps
on the battery side of the injectors would help with that?

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