Piggy backing 165 ECM chips

[Roger Heflin]

On Tue, 16 May 2000, Rick Lindstedt wrote:

> I have a thought and would like to know the consensus of "more" 
> knowledgeable one out there on this..
> 
> I would like to have a chip for motor and a chip for nitrous on my car... 
> can I use the ground pin on the chip to switch back and forth between the 
> two? and if I can ..is it possible to do this on the fly as well, ie car 
> running???
> 
> or is there a better method to this??
> 
> Thanks for any input or suggestions..

That probably won't work.  Other input/outputs on the off chip may act
as enough ground to cause trouble.

There should be a OE pin (output enable) if one was to put a gate
between the two OE pins on the chips, and the OE from the computer one
could switch one or the other.   Also if one was to put a chip that
has twice the space in it, and switch the top address line from 1 to 0
would give you two full chip spaces.   If you used a chip bigger than
2x you would have even more.   Now doing this on the fly may be a
bigger issue.

I was thinking to find a computer output (or 2-3) and find one
computer input, and use the computer input to signal enable nitrous,
and use the 2-3 outputs to trigger different stages.   This would take
some code addition, but it realisticly does not sound that bad to
implement, and eliminated some of the extra hardware (TPS switch) and
puts them under computer control.    I am going to need to figure out
if there are any extra outputs/inputs and maybe reuse some unused or
less useful ones.   That way when the computer signals the nitrous it
can also boost the fuel (may require bigger injectors, though I
figure I have somewhere around 100 extra hp in my current
injectors) and reduce spark.

			Roger

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