Yes. The Visteon ESU
PCM used by Fiesta/Focus/Mondeo at the time looks remarkably similar to the Australian Falcon ASU Spanish oak of the same period - but you know how they keep most of that stuff under cloak and dagger. The WQ Fiesta XR4/ST150 is listed as tunable in the SCT x4. As for the exhaust CAM phaser, I expect the Mazda and Ford may be different as most of the difference in those engines lies above the head casting from what my research is showing. So that is a risk.
The deck height on the Mazda L3-VE and the L5-VE are the same, with the 2.5 having a slightly different bore and crank. There are a number of sites in the UK where people have done Duratech 2.0 to Duratech 2.3 swaps. Some of them are hard core with Frankenstein setups, deleting the balance shaft and other wholesale changes to get the head with the best flow. But the gist I get from those is that the change in deck height isn't a significant problem. A few question whether fitting the MazdaSpeed LF-VE 2.3 is an option given it has better internals, but I've not seen anyone do it yet - and like I said, the direct injection.
I think the biggest change in doing a Duratech to L5-VE swap will be in the harness - but I've swapped a BF Fairlane harness into a BA XR8 before and that was heaps of fun. My last engine swap was going back 20 years though.
Regarding the
ECU - one thing I'd thought about is the recent Haltech Plug-in
ECU that comes in 2 parts numbers - probably the ABU-Black Oak and ASU-Spanish Oak versions. The main thing that has to be done is to replicate what the
ECU provides on the
CAN bus for speed/RPM/PATS security. So it may be possible that it could be recoded to support the Fiesta CAN messaging too, since the
ECU pin formats look pretty close. I've got some Falcon
ECU's here so maybe I should get a WQ
ECU and compare. With an
ECU that is more programmable, and with an additional custom connector, that opens up the possibility of direct injection control. But at $3k for the Haltech
ECU, that would make it possibly more expensive than the car itself.....
Luke