I have a 93 EG coupe that has a B16 (JDM) swapped into it by the previous owner.

The car runs great, pulls hard but will not idle very well.

A few weeks back it was surging very badly and I traced it back to a very dirty IAC valve. I removed the stock one and cleaned with carb. cleaner and it seems to be fine now.
I also tried another IAC valve that I know works fine and have the same results.

The surging is now gone, but I still have a very high idle (between 1500-2000rpm). It cold starts at 1500rpm and seems to drive fine for a bit. Then once it is warm it will idle anywhere between 1500-2000rpm. Makes the car very difficult to drive as it is constantly revving to high to drive slowly around town.

Any suggestions on what may be the issue?

 

First thought is ALWAYS air in the cooling system. Bleed out all the air.

 

FITV

 

I have bleed the cooling system a number of times. This is what I though as well but nothing came of it.

I have done every trick in the book to make sure there is no air in the system.

FITV?

 

Clean it as well.

 

I would also reset the ECU, pull the backup fuse or negative battery cable for a few minutes.

 

check if fitv is bad put your finger over the lower hole in the throttle body when engine is at operating temp and if its sucking air then its bad

 

Have you tried to see if the throttle spring gets stuck? That has happened to me a couple of times. Also, I had high idle issue and it was caused by the throttle plate being stuck from dirt and debris inside the throttle body. If the surging is gone, chances are its not a manifold leak. The idle is stable, just high right?

 

vacuum leak? sounds right adjust idle screw.