Right, I have a 1994 mk5b 3dr si, which is a 1.6 zetec, running an 'ENVY' ecu. I bought a 'CAST' ecu off ebay from an early mk6, when I plugged it in it wouldn't run, wouldn't even prime the pump with ignition on. I think it's something to do with pats as I think the mk5b is external pats and mk6 is internal, also I thought my mk5b was external edis, so I bought a 105bhp '2FDC' ecu from an xr3i, fitted that earlier and it primes the pump but will not start. Opened the bonnet and there's no edis module that I can see. Also I have an ecu and key from a 2.0 mondeo, I think the code is 'BASH', I could of swore mk5b's had external edis! So in theory the 'CAST' and 'BASH' ecu's should work if I wore the pats transceiver to the ecu???? Anyone know what pins run the pats transceiver on them ecu's? Sorry for the long post but wanted to give as much info as possible!