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DEMUX interface for Sequential COP
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Post DEMUX interface for Sequential COP 
Hi guys, I'm interested in a demux interface capable of indexing and sequencing the IGT signal from the stock ECU (to the ignitor) to run COP, with inbuilt ignitors. Either in a fully sequential configuration (4ch) or wasted spark (2ch). The circuit would require a confirming IGF signal back to the ECU and dwell control.
Maybe not an ideal arrangement, but a convienient one where the stock ECU is retained, and triggering off the distributor is required, lacking a more conventional CAS arrangement.
Looking specifically at a Toyota 3S in this instance, but certainly not the only application where this would be of benefit.

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Interesting- that sounds like a highly specific project.

For a sequential demux, you'd have to have a sensor on the camshaft, so it can be properly synchronized. Also, a way of sensing engine TDC for wasted spark.

So the goal is to bypass the ignition for the OEM ecu? And you want to not have to install a trigger wheel?

Brent Picasso
Founder, Autosport Labs
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The crank mounted CAS or cam trigger wheels would definitely be a asset to get the timing off the cam belt, but not essential, as the stock distributor mounted sensors could be utilised for the same purpose. When I say it's something that would benefit other applications, I mean Toyota and Honda use the same arrangement, but certainly not the only ones, where distributor mounted sensors are concerned.

The crank & cam sensor wheels are available readily, from several sources, but mostly utilised where aftermarket stand-alone ECU's are concerned. The need exists where stock ECU's are utilised and sequential ign is the goal, either for COP, CNP or other non stock ign system arrangement.
Basically it's something that has been looked at before, over some time, where the need exists. A basic control utilising a syncronous counter IC for indexing & sync'ing the stock ign signal, and AND gate for distribution is probably feasible, but dwell control and signal conditioning would be needed as well. Obviously external trigger wheels would have the benifit of eliminating the stock distributor completely, but not essential as such.
Where the two I mentioned, specifically Toyota & Honda are concerned, the stock systems are basically identical, other than one triggering off the leading edge of the ign signal and the other off the trailing edge.
Going to a stand-alone ign system isn't the requirement as such, but keep the stock ECU generating and controlling the ign signal, and using it in stock protection strategories is. Simply intercepting that signal, and using the stock triggers to condition and distribute that signal in a sequential arrangement is.
Well I think you see where I'm coming from, any thoughts on the subject..

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