Just wanted to post the fix i found for the tach not working in my swap, don't know if it's been posted yet or not but here it is anyway. When i did my swap i used a 92 harness and coil packs ect, and a 90 ecu. Did the two wire swap on the ecu (air flow and idle switch.) and wired up the 15 pin and 4 pin connector, no problems. But tach didn't work as usual, because of the lack of a tach filter. Took the tach adaptor from a 90 coil pack (NT, turbo 1.6/2.0 all the same) here's a pic http://www.ecanfix.com/~mdhamilton/imag ... AGE002.jpg
Wire the two inputs red and white to the coils and send the yellow output wire to pin #3 (white) on the 15 pin connector (C-19). And now i have a tach. Hope that helps some one.