You can't use an obd0 pr4 on an obd1 system; you'd have to convert your car to obd0, which would be dumb. I believe you can do a 1-wire vtec conversion on obd0 pr4 ecus, but it's prolly in your best interest to avoid the hassle, and spend a little extra cash on the p28. They aren't all that expensive. But go on to pgmfi.org if you want to learn more about ecus, there is a LOT more information than you'll ever need there.