I have just completed a mk1 g60 conversion in my Mk1 using a Corrado ecu & loom. The car starts and runs fine, however when under load it develops a mis-fire @ 4-5K rpm. I have checked fuel pressure and it does not seem to drop off so my suspicion now is ignition. The g60 ecu pin out shows 2 earth connections, one to the battery earth and one to the cylinder head, but when I was wiring mine up I just connected both to the same known-good battery earth behind the dash. Is there a specific reason why the ecu has two different earths, and one is earthed to the engine?? And will connecting the engine earth to a battery earth affect the ecu?