I don't think he meant speed sensor. The pre 91 doesn't have one. I think he meant ais. The settings all need to be adjusted and by adjusting them you check to make sure they are working correctly. Got the pm but it sounds like you are doing ok. If you need more help let me know. Finding a replacement for the ait is difficult but the coolant temp sensor is a good replacement of you can get a connector for it or solder it.