Ancient History

[Todd Knighton]

> 
>  Once you go to full throttle the injector pulsewidth should approach
> 100%; basically the injector is on all the time.  At idle and low RPM
> the injector timing makes a small difference, but it's mostly an
> emissions thing.  Lots of quite efficient cars simply batch left bank,
> right bank, and to hell with trying to time it.
> 

If you run the injectors beyond 80% dwell, they become erratic and the
flow rates go to hell.  Stay below 80% and you'll make your engine much
happier.  Also, if you're running above 80%, you can burn your driver
circuitry out prematurely.
As well as, at idle and low rpm, small changes in injector timing make a
hell of a lot more difference than at high rpm.  It's the percentage
thing.
for example

Idle timing
1.5ms
change timing .5ms
that's a 30% change

Full throttle timing
10ms
change timing .5ms
that's only a 5% change

Low numbers are much more critical.
Even worse are high rpms, light throttle.  At 6000 rpm's there's only
10ms from TDC to TDC, and if you're looking for 8 bit resolution you're
alread into the 1.25ms per step, go 10 bit resolution and you're looking
at 9 microsecond resolution.  Where at 600 rpm's you've got 100ms from
TDC to TDC and ten times the time to work with.

Todd Knighton
Protomotive Engineering