pulse width / pulse granularity

[Neil Bradley]

> >  injector? Would 250 microseconds be long enough? I'm trying to nail down
> >  injector pulse length granularity so we can figure out our requirements
> >  for the "slave" pulse width generator.
> So far I saw a couple people address the minimum pulse width question,
> but I don't think I've seen anyone say anything about the granularity,
> IOW the smallest increment by which the pulse can be adjusted. It
> seems that most everyone agrees that 250usec is way shorter a pulse
> width than you're ever likely to need, but if your pulse width is
> only adjustable in 250usec steps, I think you'll find that way too
> coarse. (Ok, maybe not for a dedicated dragster, which need not idle

Think so? I'm certainly not going to try to pass emissions, but having it
streetable (meaning actually drivable) is always a possibility.

> politely or pass emissions.)  Consider that if your minimum pulse
> width is 1msec, and you'd like to be able to adjust fuel in 2% steps
> at idle, you need a 20usec resolution. (At least, probably a lot
> finer due to injector flow-vs-PW nonlinearity at low PW.)

I noticed that the Haltech solution only allows increments of 256
microseconds each. Would changing the pulse by less than 250us really make
*THAT* much of a difference?

> For a race car probably none of this matters. I just wanted to make
> sure that minimum pulse width was being addressed separately from
> granularity.

Your suggestions and replies are greatly appreciated by this newbie. ;-)

-->Neil

-------------------------------------------------------------------------------
Neil Bradley            "Devo was exquisitely stupid. But we knew we were being
Synthcom Systems, Inc. 	 stupid, whereas a lot of people are stupid and don't
ICQ # 29402898           realize it." - Gerald Casale - DEVO Cofounder

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org