Hello! My accord is doing the usual surging idle that I have seen in no less than 30 posts on google. I have bled the coolant, taken off and cleaned fits and iacv. Replaced fire and iacv. Cleaned tb and plate. Cleaned egr. Checked and replaced vacuum lines. The only difference that I am having is that when I have taken the intake hose off then let it warm up, I put my finger on the bottom port like I see in a lot of posts, it idles perfect, a little low but a steady idle. My thought was that I just replaced the Fitv and screwed the yellow plug down then backed off a squeak, how could it be that? So I make a block off plate and sandwiched it in there, to “delete” the fitv. It still surges, and still very strong suction from bottom port in tb. The problem started when I noticed it loping just a little so I replaced the spark plugs and did an oil change. Then It got more pronounced. I have tried to read as many posts as I can to figure this out, but my issue is always that little difference. I always see the poster saying that the bottom port would cut off the engine or no difference, not getting better. Thank you for any help! Also I almost forgot, I was looking through the webs in the intake manifold last night and I could have sworn that every time the engine surged I could see an arc right above the oil filter. Tried to replicate it this morning and I couldn’t see anything arcing. I even jacked it up and cranked it to look under the intake and still didn’t see anything. Hope that helps

 

Different generation accords had different port layouts. If you can, follow the port to the component that will bypass the throttle plate with air. On the 92, there is the FITV, Air boost valve, and IAC.

High idle is caused by too much air entering the engine, or air in the cooling system. The excess air can be from intake leaks, or failing bypass valve(s) like the IAC, FITV, and air boost. Keep troubleshooting and don't assume a new part is working properly.

You also mentioned tightening a screw. Is that the FITV mechanism, or the throttle plate stop screw?

 

I was talking about the yellow plug in the fitv that you can adjust. I have sprayed cleaner everywhere and can’t hear a difference in the idle, although it’s very hard to distinguish when the rpm’s are bouncing up and down! Everywhere that I have read says that the bottom port goes to the fitv. The fitv was a rock auto part as was the iacv. Also, I checked the tps and it passed with .5 at close and 4.5 at wot. It really aggravated my ocd to have to pierce the wires to test it! Lol with my 280zx I test for ohms at the sensor not the wires. It blew my mind. Would you think that the fitv is still the culprit with the change when I plug the hole with my finger? It’s like it won’t close up. As far as I know to close it up you turn the yellow plug clockwise right? Is the air boost on the very end? I thought that was the fuel pressure regulator. When I put my finger over the vacuum line going to it, it starts making a sucking noise from that component.

 

The FITV is open/closed with coolant tempeature, so the FITV should have coolant flow. I recall from a post a long time ago that the coolant lines or the passage through the FITV was blocked with some kind of salt/precipitate. Just make sure the coolant is flowing. When the coolant heats up, the port to the FITV should have little to no vacuum. I remember setting the FITV to snug and didn't back it off at all on my 95 accord.

The air boost valve will also bypass air, so that line going to the intake tube (I think) before the throttle plate can act as an air leak as well. Try plugging that line to the air boost with something like an old spark plug. I can't remember what conditions that air boost valve should open.

 

So I made a block off plate for the air boost, used felpro gasket paper to make sure I didn’t have any leaks from the block off plate. Cranked it up it runs much better, no surging still running pretty high rpm’s. I unplugged the iacv and it idles around 1000. After warming up it bounces from 1100 to 1300 rpm’s. Fitv plug is tightened all the way in.