Injector control question

[Johnny]

MaxBoost at aol.com wrote:
> 
> > I'm asking because I don't know ..... still seems to me that
> > knowing the duty cycle is more important (and much easier to
> > measure) than actual pulse width time.  If you're worried about
> >  *when* the pulse is triggered relative to the valve opening
> > (I assume we're talking a certain no. of degrees from TDC),
> > then that's another kettle a'fish again -- isn't it?
> 
> I don't know of any current production engine that uses anything other than
> closed valve injection.  That means you fire the injector onto the backside
> of the warm intake valve and let the fuel start to evaporate before the valve
> opens.  Every thing I've ever read on open valve injection says that you
> cannot get good enough vaporization from the injector alone and you will wash
> the cylinder walls down and 'make oil'.  IF you could aim the injector to hit
> the very hot exhaust valve, then you would have something, but getting an
> injector to hit the exhaust valve on a current engine would be quite a trick.

Does this mean that all of those first years of GM TPI are sequential
injection?

-j-