[Diy_efi] Simple EFI

[frederic]

> 555 EFI is still a concept and my experince is mostly with Digi
> circuits so I have ruled out the possibility. I next tried using
> sourcing 8051 based EFI by Al Lipper but it is not online.

Yeah, Lipper's neat design doesn't seem to be available... not sure if 
that's permanent.  Since you're familiar with digital electronics, this is 
not that far off:

http://www.diy-efi.org/diy_efi/projects/PC_EFI/

Replace the PC with something else... PIC, 8051, Z80, whatever you're 
comfortable with.

BTW, the "trick" to the 555 timer is to set it up as a one-shot instead of 
a continuous multivibrator - triggered off your distributor.  When the 
distributor sparks, the 555 timer adds fuel for the next firing, since 
it's triggered at the same time.  Though you'll have static timing from an 
injector perspective, but for an experimental engine on a bench you can 
get it to idle, and rev a little bit before you need more pulsewidth.  I 
managed to get a Buick V6 with a TBI "carb" to fire this way.  Took a 
while to get the resistor/cap values corret, but I eventually got it to 
idle.

> I would like to have guidance from somebody  who may have already
> built a simple EFI like the one I am planning (Links to some
> circuit?),  Since my experince is more with eletronics and less with
> automotive engineering

Another place you might consider reading through is: 
http://www.megasquirt.info/

While you could easily just build it "as is" and join the megasquirt 
community, even if you decide to do your own thing it's still worth the 
read-through.  The designers not only put together the schematics and 
board layouts, but also put a lot of effort into the explaination of 
theory and timing charts and stuff, might help you out picking up the 
automotive aspect of this, thus helping you with your own project.