I just swapped a b16a1 into my 91 civic si and everything seems to be working fine except when the engine gets to operating temp. the idle starts jumping from about 1300 rpm - 700 rpm when it idles. Does anyone know what to do to fix this? I have been told that I might need to adjust my idle adj. screw on the throttle body, but Im not sure. Please help!!
thanks!

does your check engine light come on? I cant help you but I sorta have the same problem, except idle is fine but check engine light comes on :dunno:

No, my check engine light doesn't come on.

your idle air control valve is messed up its ubder your intake manifold thats teh prob

Sounds like ECU to me...

I had the same problem, it turned out to be my idle air control valve

ihad the same problem with my b16 '91 CRX,and i fixed my idle control valve under the throttle body and the idle still keeps jumping around,anyone else have a problem like this and know what to do?

and my check engine light is on...