Injector Firing Voltage

[Ward]

On Sat, 15 May 1999 16:12:57 -0400, Bruce Plecan wrote:

> I hooked the scope up to a GM ecm running 8 saturated injectors.  The
normal
> 12v only appreared rarely.  The usual voltage of the injectors firing was
> 75-100v..
> So this flyback/kickback, is a very large issue.
> This would seem to imply to me, that the stock ecm doesn't clip the
voltage
> by reverse biasing a diode, to contol it, but rather use a scheme, where
> they deal with it.  Maybe clipping these signals has a adverse affect on
the
> injectors opening/closing..
>   Jus curious, if this makes sense.
> Grumpy
> 

Yes, it is flyback, the same thing that cause you ignition coil to work, the
high voltage is immediatly after you open the circuit, just like opening the
points in a braker points ignition.

Its not important to clip the fly back volatge the drivers are able to
handle it, and clipping tens to extend the pulse width.

Just had two F18's fly over at low altitude, thats unusual.

Ward




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