Single hole is a pintle-type and the disc-type are multi-
hole, is my understanding; I believe the Delphi are all
disc-type. Maybe you got the Bosch 42s instead? I'd
check the P/N vs what your invoice says was ordered.
Pintle or disc both will produce an atomized cone.
Final vaporization is gained off the backside of the
hot valve. A broad cone may partially miss the valve
and hose down the walls, and puddle some of it
Disc are supposed to be more resistant to fouling
(at least, according to the prople who sell disc
type injectors). Various injectors will have different
spray cone angles, which play better or worse
against the intake runner and valve position; they
will have different actuation times and low-opening
delivery, which wants the injector offset data to
match. Some will, and some won't, be "close enough"
to stock injector time-characteristics to get by with
no adjustments (and no data) other than main full-
open flow values.
I'm pretty sure you could work your way to a proper
offset table but you're basically on your own, for it.
Though someone with an injector flow bench, and
variable voltage & pulse width drivers could get the
data, very few price-shoppers would pay the tab I
expect. You're talking thousands of dollars in gear
(retail; you could cobble if you had hoarded the
right stuff) and somebody standing around taking
high grade data for about a day if you want to fill
in the whole offset table cell by cell. Show of hands,
who wants the bill? Thought so.
But in the other thread I did outline one notion of
how you could back into a semi-decent offset table,
using in-car data. At least for the "normal" voltage
rows. And presuming an otherwise error-minimal
air fuel calibration, pre-swap.
If you have too rich an idle (- LTFTs) then reducing
the offset table values will lean it out.
However, over-enriched idle can also be an artifact
of the pump/regulator operation (higher pressure than
modeled, at idle). The IFR table assumes a dead flat
pressure, square-law pressure vs delivery which is
all not true, regulator slope and forward run drops
are not modeled in the IFR table (it's a straight line,
sqrt(vac) style). With a rail-mounted regulator this
might be more true but stock, it's only "close enough"
and you're not stock, by the time you're buying big
But I suspect the tuning "issues" people have been
encountering, lie with the differently-constructed,
different-timing injectors and the offset table, more
than with the line pressure deviation. Though, if you
stack a new pump and new injectors, you have
double the fun. Or maybe, fun squared.