There must be some connection between the wiper fuse / power supply and the immobiliser resulting in the strange behaviour described earlier. I am an engineer and could not imagine such a relation, but it's a Morgan.....
Hi. Just a thought whilst reading. When the key is out of the ignition does the PATS led stop flashing when you remove the wiper fuse? If it does you may well have an ecu start up delay.
The ecu will have numerous power feeds that become live when the ignition key is turned on but there will be one +12V pin that keeps it awake and powered even when the key is out (pin 55 on mine). It enables the ecu to stay awake, keep the immobiliser active and also retain the memory. If the flashing PATS led does stop flashing when the fuse is out the stay awake line will have been lost as it’s sharing that fuse too. The ecu will only then get power when the key is first turned on. So it may not start instantly as there will be a finite time for the ecu to come to life.
