Hi there all, new forum member, newish 1985 XJS 3.6 owner, starting to iron out a few of the niggles and while the wiper motor was off for repairs I was going to have the AJ6 Engineering mod on my ECU. So I go to the passenger footwell to retrieve the ECU...

Can I find it? No. Am I being really stupid? Probably. I've had the carpet up, the side panels out. Where is it??? Help! Dan

 

I am only familiar with that V12 modes but they are all (assuming it is EFI ECU you mean) in the boot/trunk.
R/H side above rear wheel well.

 

The 3.6 ECU is under a board at the end of the passenger footwell. Lift the carpets and you will see it
Greg