Affordable Wideband ECUs - How to?

[Chad]

>There was some discussion early on, and then later some also in private
>amongst a couple of us, about the possibility of programming an OEM
>controller like the GM ECUs to force it to stay in closed-loop even at
>high TPS and load, and trick the controller by mimicing the
>stoich-crossing to occur at whatever AFR you chose. This was essentially
>the idea of simulating the stoich-crossing input to the OEM controller,
>and use an EGOR module (or an NTK box, or whatever) to allow "moving"
>this simulated stoich-crossing to whatever AFR you commanded. Bruce
>Plecan and some of his GN/GM buddies apparently looked into it, and
>decided there likely wasn't enough "authority" in the tables that could
>be reprogrammed, to keep the controller forced into closed-loop, and
>gave the idea a miss, suggesting that you really needed to get at the
>code to do it right. But coaxing those extremely affordable OEM
>controllers to make the transition to WOT closed-loop controllers sure
>sounds like a wholesome grail worth somemore pursuit, purely from an
>economics standpoint.


I have a unit up and running right now that does exactly that, allow the 
user to change the stoich point that the O2 sensor reports.  It works quite 
well, and you can watch the A/F change as buttons to rich/lean are 
pushed.  The flaw in getting the ECU to continually run in closed loop is 
that this is only manipulating a control input. In effect, you are *asking* 
the ecu to change the pulse width to the injectors rather than forcing it 
to run in a certain way.  The changes only occur at idle and cruise, when 
the ecu is paying attention to the O2 signal input.  With the experimenting 
I've done, I agree that you need to have more authority (source code) in 
order to force the ecu to do what you want it to.

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