I've searched and I found a lot about idle problems and solutions but my circumstances may be a little different.

I just got a 1998 obd2 b18b swapped in my 2000 civic coupe and I'm having idling issues. Currently I am running an obd1 ecu because I couldn't get a hold of an obd2 ecu (p75?). The car idles fine when warming up but when I go to drive it I get a solid CEL and when I'm in neutral the idle is bouncing around at almost 0rpm to around 300rpm. It almost wants to stall. The car drives absolutely perfect other than the crappy idle.

I'm going to clean the IACV and possibly adjust the idle adjustment screw as my last resort but is this idle issue and CEL being caused by the obd1 ecu being used on an obd2 motor? Thanks for your help

Oh and I forgot to mention that the speed sensor in the trans is currently not working and getting replaced soon so my speedometer does not work. This probably has nothing to do with the idle issue but I figured I'd let ya know.

 

Vss has nothing to do with the idle, also make sure your coolant system is bled of all the air.

 

alright thanks I'll check the coolant system tomorrow and clean the IACV. But like I said does having the obd1 ecu have anything to do with the crappy idle or CEL?

 

on the very right side of your head check to see if the p75 matches with the computer code i have a 98 ls in my civic and its a pr4 with a pr4 computer just check that as a double check but make sure you dont have a vaccum leak anywhere that can cause an idle surge along with the air in the coolant system but check those things out especially the computer and head code

 

well problem is solved for the most part. one of the vacuum lines around the intake was coming off a little so I made sure all of them were tight and it's idling perfect now. thanks for the input tho guys