rubes,
were the cables burnt or melted?
if burnt then a short circuit from the internal circuit would have melted thus burnt this - check for short circuits in the area
if melted, then heat from surrounding parts, i.e. starter, alternator, etc may have melted it- theory
from your explanation , when you said your car had more power, i believe that was then when there was a short circuit, causing the injectors to probably open up ,resulting in more petrol and power increase
were there any servicing/mods done recently to the engine bay?
sometimes this short may not appear in the engine bay side, but from the base of the harness itself, do check the wirings from the ecu onwards and see if there are any shorts- loose circuits, hanging wires etc
another long shot - heat from adjacent parts may have heated up the wires,not necessarily near, causing the shorting, and the shorting went all the way to the injectors end, excessive current melted and burnt wires there, question now is where is the shorting.....and where is the heated part
do check if there were any parts changed recently to your car, or did you go through bad roads etc,etc, would help narrow down the cause
you'll definitely have to replace whole harness from ecu to injectors, i only have a spare m52 ignition coil cable set, but you probably won't need to change it
