93 civic with 2000 SI engine transplant. hoping a honda tech out there might be able to help. there are 2 passages in the T/B just before the throttle plate. i believe the upper is for IAC and the lower is for the cold/fast idle thermal valve.(not sure if that is the correct name) is this correct?

 

One should be for your MAP sensor, the other for your FITV, if memory serves correctly. Let me double check that though.

 

Are you using the SI's TB, or the 93 TB?

 

Good question! i know the dist is the 93. any ideas how to tell on the T/B

 

If there are two holes just inside the mouth of the throttle body, it has the provision for a FITV (Fast Idle Thermo Valve). If you are standing on the passenger side of the vehicle facing the T/B, the IACV (Electronic Idle Air Control Valve) hole is located at the 10 O'clock position and the hole for the FITV is located at the 8 O'clock position.

Now, while the car is running and idling, place a finger over the lower hole (8 O'clock position) and see if the idle speed/sound changes. If it does, then this is your problem area. Remove the 2 8mm screws holding the end plate on and screw in the nylon plunger fully, then back off 1/2 turn. This may be easier if you remove the T/B or the FITV from the bottom of the T/B first. If there is no audible change, cover the upper hole completely. This should drop the idle down to 500 RPM... or even stall. If so, it is operating normally.

Good Luck.

 

Thanks to both for the replies! i thought i was correct but i'm not real familiar with honda's cold start system, so i thought it best to ask. car came to me with surging idle when warm. hooked up my tach surging between 900-1500 rpm. add propane, idle smooths. unplug IACV, idle smooth bu 1500 rpm. sweep for vac leaks, none. cap vac ports for booster & pcv, no change. covered 8oclock hole with my finger, idle stable @ 800 rpm. removed cover onFITV (now i know it's correct name!) sprayed a little carb clean, worked plunger in & out, blew it dry & reinstalled cover. could not get to it to try and screw it in but idle was smooth in the bay. however surging returned on test drive. will pursue this further tomorrow. again thanks!

 

well, i removed, cleaned and adjusted as per above post. now it starts surging right away(C/T @ 70F). covering the 8oclock port in T/B has no effect. however covering the 10oclock port (IACV) brings the idle stable @ 800 RPM. bled cooling system and brought it up to 195 degrees F for 2 fan cycles. runs and reacts exactly the same as cold. while i had the FITV off, i cleaned the T/B because it was very dirty. i also tried to rest base idle speed per specs but it would not go below 1000 RPM. i removed the IACV and blew through the ports, there was flow. i thought it would be closed until plugged in? any thoughts would be appreciated. thanks in advance!

Forgot i checked and this engine is not from a 2000 SI. it is a B16A3. i believe those were in 94/95 DEL SOL

 

Thought i'd post this in case anyone's interested. new IACV came in Friday, almost pulled a check muscle trying to blow through it, as i expected! however, since i believe in being through, while i was waiting for it i checked all the basics. as it was clear there was too much air causing the high idle i focused on possible vacuum leaks. checked the MAP, TPS & 02 just to be sure. all looked good.
Installed new IACV, bled cooling system & adjusted base idle. all is good! THE HONDA HAS LEFT THE BUILDING!
It appears i had a combination problem. both FITV and IACV were bad but the IACV wasn't causing an issue until i cleaned the T/B and upper intake allowing good airflow. at that point the partially open IACV was allowing to much air to bypass the throttle plates and drive the idle high.
I learned something here! which is always a good thing. apparently Honda's program strategy is when the ECU sees RPM above a certain # (1200-1400 not sure) and the TPS at closed throttle, it goes into decel mode (thinks you let off the gas and are coasting), at this point the ECU cuts the fuel injectors until the RPMs come down, then starts them again. this is what causes the surging.
Bottom line is, fix the air leak= fix the surge!