View my fuel log 2015 Mirage ES 1.2 manual: 44.1 mpg (US) ... 18.7 km/L ... 5.3 L/100 km ... 52.9 mpg (Imp)
Any pictures? It would be good to see what happened.
Do you suppose this could be related to your engine swap?
Wow good job finding the problem yourself. Problems from corroded wires are usually the toughest to find