Injector control question

[MaxBoost at aol.com]

> 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.
 Of course the above doesn't apply to the new direct injection engines
developed by the japanese in the last year or so.  Also this is in
consideration of lower engine rpms, at high speed the cycles occur so quickly
that the injector is open most of the time anyway.

FWIW the Nissan CONSULT diagnostic computer gives a direct readout in pulse
width.  Many of their ecu's also have a pin that is dedicated to read this
function only.

Max