i just swapped out my obd2b ecu for an obd1 chipped p28, everything is fine and dandy on my b16a2, but on cold starts my idle is pretty irratic and will even sometimes die unless i hold my throttle open for 30 seconds or so, then it will rise and fall between 1000-1500 before sometimes settling down to regular idle, i havent touched anything other then unplug my ecu and plug this one in, so it cant be vaccum related, does anyone have any ideas?

 

car runs stfrong no noticeable power loss

 

put the old ecu back in and see what happens.. i had a car that used to do that too, just ignored it

 

works fine with old ecu