IPD didn't build the boxes, they just made a simple modification to them. Basically, a little switch box full of varying resistors that intercepted and modified the coolant temp reading. By making the engine think it was colder, it got it to enrichen the mixture. They just did the modifications to stock ECU boes. For that matter, they could probably have just made this a plug in gadget, with wiring that plugged in at the coolant sensor, but perhaps selling the whole box made it a bit more mysterious at the time, and helped justify the pricing for the modification.

The problem with the cold starting on my old 1800E is that the original computer died on me, and I couldn't (pre internet days) find the proper replacement, so I instead installed a later model box that happened to be already IPD modified. (I snagged this off my '72 1800E after it got totalled by a stop-sign running Chevy). The early boxes had computer controlled cold start valves, that is what the 71 is wired for. The later cars had cold start valves operated externally from the ECU, with a wire going from a terminal on the starter (hot when cranking) to a thermal switch on the right rear side of the block, and then to the cold start valve (the other terminal was grounded). Thus automatically firing the valve when the engine was cold and cranking. To get it to work on this car you'd either need to add a thermal switch and wiring from the starter to it and on to the cold start valve, or track down the proper early box.

As for the firing sequence, I haven't heard of that, but there's a lot I haven't heard about I'm sure. But the box in it right now is probably at least as late as 72, possibly a 73.
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I'm JohnMc, and I approved this message.