You could get a OTC 2000 or 4000 scan tool it works with your 85 ecm and shows you everything you need. Its just a show the data at a slower rate and does not data log. Its the tool the auto shops use to use in the day or they still might. Do a search on the board and on ebay for ones for sale. Just make sure you have the cig. lighter adapter, the unit, cable hook up to GM cars, GM cartridge. They are cheap too!!$25 to $65 -Nick.