Here's the issue with PlugNPlay ecus for the Capri:
The VAF unit should be deleted, because an aftermarket ECU doesn't need it. The fuel pump switch & IAT sensor live in it. So if you delete the VAF, you'll need to wire in IAT and fuel pump circuit. I see that speedyefi has a solution for the Miata to run an IAT with the miata VAF plug.
The stock ignition system, which sucks and should be upgraded if you're running an aftermarket ECU, runs nearly independent of the ECU. So to upgrade the ignition system, you have to delete the stock system & wire in all new ignition system. This includes a new crank trigger & cam angle sensor to give the ECU a high resolution tach signal for things like sequential ignition
The stock fuel injectors are hard wired for batch injection in the injection loom, which most modern aftermarket ECUs can do sequential injection, so you'll have to add wires to the harness for the extra injection channels.
So right there you're not using parts of the stock harness, and are having to add in another 15-20 wires for new sensors / injection / ignition control. Not so PlugNPlay.
If you're retaining the stock distributor it's not as big of a deal, but the stock system has so many compromises that IMO it's just not worth it for a PlugNPlay set up.
There's no "good" option. Unless someone standardizes crank triggers & coilpack/cop setups, and makes a custom engine harness. But that's $$$$
The Escort GT ecu has partial ignition control of the distributor.
The Miata ecu has full control of the ignition, it has coilpacks and a low resolution crank trigger/cam angle sensor.
So it's a bit easier for them to make the stock harness work
One of the Capri guys I know is going to attempt to use an early 90s Miata harness to get around these issues, but it is a RWD car and I question its fitment into the Capri, plus the Miata uses a handful of different plugs/sensors that will all need swapped over. And also needs integrated into the chassis harness.
Sorry this isn't meant to shoot the idea down, I have gone over all the logistics in the past, I myself was going to build PnP Megasquirt units but again using the stock harness with a fully capable standalone ECU really limits your setup. See this thread:
http://teamcapri.com/forum/index.php/topic,2924.msg131772.htmlYou could send this post to the speedyefi guys and see if they have any solutions.
Here's the ECU pinout:
http://werbatfik.com/uplimg/b6tecupinout.gif