ECMs

[Tom Sharpe]

Frederic Breitwieser wrote:

> > For all you EE types out there. Can I take my running 68HC11 EFI and
> > hook up the new '332 to the same input sensors and run both without the
> > outputs of the '332 hooked up?  Can I add additional Inputs to the '332
> > and hook them to the HC11 Injector output and monitor (and log) the
> > 'HC11 functions?  If so, I'm a lot closer to some real world testing.
>
> Yes, but no.
>
> yes you can run a MAF or O/2 sensor connected to two 68HC11 chipsets, but
> dont forget the A/D inputs do have an input impedance that needs to be
> dealt with.  I would envision you already have an op-amp or other
> stablizing circuit off each sensor to "convert" the output to a 0-5V swing,
> thus you could tap at that point with minimal issues.  This I've done.  I
> just wouldn't connect to two 68HC chips directly to the sensor.
>
> Buffering with an Op-Amp is very simple.  I've used older high-impedance
> chips like the TL084 quad jfet op-amp with the 68HC series with great success.
>
> And radio-shack has the TL084, or they did.
>
> Frederic Breitwieser
>

Fred,

I was thinking of connecting at the wiring harness, not internally to the ECM. Do
I need to make a board to sit between the sensors and the ECMs? What would it look
like and which sensors need buffering? I'm thinking of my Edelbrock ProFlow w/
68HC11 and the EFI332 that is being built by this group.

Regards  Tom