unplug the ISC then set the BISS and trottle plate stop and TPS with it as close to 1 ohm as possible but not on of over (if it's a 4 wire) under 1 ohm = throttle close wire live tells ecu it's at idle over 1 ohm tells ecu throttle is in use.
if you don't unplug the isc when you adjust the BISS you can go to far so unplug ISC and then use BIS with timing locked to get a base idle of 850+- 50 rpm this should also be done at operating temp
