I am piecing back together a 95 ex civic coupe junkyard retrieval. Going pretty well, but have a problem with a surging idle 1000-2000 rpm regardless of hot or cold. No codes from ecu. Replaced EACV to no effect. May have a vacuum line mixed up, but who knows. One suggestion is PCV is shot, have not tried this yet.
Surging idle is a very common problem on this car and there are many long threads about it on various forums. If you are unsure of your vacuum lines then that is where you will want to start. Second most common cause is bubbles in the coolant, so bleed them out. Third most common cause is a bad FITV valve.
I've not seen this type of problem be PCV related with one exception. The lines for the PCV are made of relatively soft rubber and are are prone to dry rot a little bit, it's possible you've developed a small leak.
I agree with suspendedhatch with the FITV suggestion.
While there are some idle experts paying attention, I want to ask a related question about Honda idle.
I have a '95 VX with A/C. The car has less than 110k, and is generally in great shape and runs great. I've done all the typical tuneup stuff myself, including timing and valve clearance. It idles nicely and I've checked the idle spec with a digital tach, using the procedure in the service manual. The idle does the right thing when you turn various accessories on and off (aside from A/C).
The problem is that the A/C sometimes causes stalling. The problem is a bit elusive. It doesn't always happen.
I realize the ECU is supposed to get a signal that the A/C is on, and boost the idle. This part seems to work. Idle speed jumps up immediately when the A/C is turned on. It seems pretty clear that the ECU is getting that signal, and responding. But sometimes the engine will stall, a few moments later. Or sometimes it will idle fine, with the A/C on.
There is another problem, that seems separate, but maybe is related. There is an A/C leak, and I'm going through some steps to find it and fix it. But when the system is charged, it cools nicely.
Is it time for me to take apart the IACV? I have tended to think this is not the problem, since the car idles nicely at all other times.
Or maybe somehow the compressor is producing an extraordinary amount of drag, but only under certain conditions. That's sort of what it feels like. But that doesn't make sense, because the system seems to work fine, when charged (aside from the stalling problem).
Turning on A/C tends to cause stalling, whether the system is charged, or not.
I would greatly appreciate hearing any ideas you folks might have.