1991 Honda civic wagon
1991 full b18a1 swap (tranny,axles,header,im,tb)etc
obd1 ls dizzy, p75 ecu

Ok so basically like the title says my idle is surging, well it wasn't doing it before I converted to obd1, so I did the Normal checked the fit valve and what do you know it was loose so I tightened up the plunger type thing.Then no more surging, then the other day I notice I forgot to plug my tps back in after bolting my fit valve back up so I plug it in and start my car and what do you know surging idle again! It's not a huge surge except when cold when it's warm it's usually around 1000rpms to 14-1700rpms not sure, I k ow someones had this problem I know it could be my jumper harness considering I already had to re wire my 02 sensor that wasn't wired right anyways any ideas help.

Ps. Already cleaned iacv and checked all vaccum lines

 

Have you double checked to ensure your coolant is topped off? I know it sounds crazy but when mine surged like that, it was low on coolant.