When putting an 1800 XR2I Zetec engine in a Fiesta SI 1600 how do the Ford chips work the imobilizer and does the key have to match the ECU or does the chip work another way?

Answer 1

As far as I'm aware the early XR2i 1800 ecu does not use PATS so when you place the xr2i ecu onto the Si loom the wires which would have controlled the injectors are now connected to the wires which goto the external pats unit, in order to get the vehicle to start up, you need to get a wiring diagram and swap the pins/wires around on the loom that plugs into the ecu to get the injectors to fire you would also have to disconnect the external pats unit,

i had this trouble when i put an Xr2i ecu onto my loom,

the fiesta Si uses External pats, if you pull out the little tray or air bag unit on the passenger side you should be able to see a bundle of brown wires apparently it is possible to earth a few of these wires and move a few around to by pass pats

you can probably run your 1800 engine using your original si ECU it will underfuel at high revs, but you can combat this with an FSE Powerboost valve/fuel regulator and a supership or powerchip or unichip