Re: Injector Duty cycle calculations

["Bruce Plecan" <nacelp@bright.net>]

> Yes - this is why I am thinking of switching to 30lb injectors.  I don't
> want to run 50+ psi at the rails.  I'm shooting for mid 40's.

Just check that you have some return line pressure.  Operating at 50 ain't
anymore dangerous then at 40.  Just for grins, I do like AN, thou

> >I'm dumb, I just remember 10msec at 6K is 100%, so atta glance your
> >about there.

> Yes - this is exactly what I am thinking too.  Let me ask you a quick
question:
>  When the 730ECM reports injector on-time (pulse width), is this the
amount
> of time the injector is on for ONE off-on-off session or the amount of
time
> spend in a double-batch fire (off-on-off-on-off) session?  Its just hard
> to believe that Diacom is reporting 8.3-8.5ms at 6000+ RPMs.  That would
> mean that my injectors are actually on for 16.5 to 17.0ms per 4 strokes.
>  That's A LOT of fuel.  Does that sound correct?  Furthermore, when you
> consider the fact that my 24lb injectors are operating like 28lb injectors
> (due to the greater Fuel pressure) it makes 17.0ms of on-time seem like
> a A LOT for a naturally aspirated 350 for one 4-stroke rotation.  Any
thoughts
> on this?  What does your EFI experience say?

Well, we differ in our ways here.  At the higher RPM I rely on reading the
plugs, and measuring performance.  I could care what msec diacom is
reporting other then for diagnostics.  If the car is running right then I'd
remember what the PWs are for that level of performance.

> >If the 10 is correct, then he's not in a SEFI mode.
> >10 at 6.5K batch means he's static (injector always on).

> Or Diacom is reporting wrongly for either his car or for my car.  We are
> running the same injectors, the same type of intake manifold, and the same
> heads.  His car is faster by a bunch (about 75 more hp - track proven).
>  I would think that he would need to have more fuel and therefore a
greater
> pulse width.  This is just very wierd.  I just want to make sure that if
> I get the 30lb injectors that it is the right decision.
> >Really sounds like he's batch
> When did GM switch to SEFI?  I made a slight mistake.  The car is a 1996
> Pontiac Formula with the stock ECM.

The pcms ecms can switch modes.

> >Might give em a call, and ask if there are issues about this.

> Will do.  Thanks Bruce.

> >Get some used GN ones, I just bought a set of 6 for $15.  For the price
> >of checking them, I can't lose.
> I'll probably go with a set of SVOs.  I can't leave anything to chance
given
> my goals.

???, saying money isn't one of your goals?.
If a shop flows the used ones, that is more accurate then assuming the new
ones are right.
Grumpy
>
> Tim
>
>
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