95 honda idle surge.

when I partially plug the top hole on the throttle body on the electric side, the car idles perfect, but when I let it open it surges again there is a lot!! of air flow going through the top hole. I already tightened the thermal valve but it didn't solve the problem. please help!!!

Well, it appears that top hole is allowing air in, creating a surging/lean condition.

Hondas can go crazy when they go lean.

I don't recall the hole you are plugging. Could you please upload a picture unless someone that knows Hondas gives you the answer?

Just another thought.

Perhaps your IAC is stuck. To determine that, use the butt on a screwdriver and tap on it. Don't do it too hard since you can damage the actuator's internal magnet. If by tapping on it, the idle gets better, that means it is sticking.

I've had decent luck cleaning them, but the best is just to replace it.

It is the top hole inside the throttle body (see picture) it appears that the electronic IAC is what controls the amount of air flow going through it. Perhaps a faulty IAC? or just stuck on open?

I was able to get a check engine code, code
# 1 4 IAC, idle air control valve. I will investigate further tomorrow. What do you recommend I use to clean the valve?

Update. I unplugged the the connector while the idle was surging, I got a check engine light but the idle came down to normal, and remains normal, I'm not sure where to go next.

whats the coolant level? I know when those Hondas get low on coolant they will surge

Did you slightly smack on it? Did that help? What you're doing is unsticking the mechanisms inside.

With Ford IACs, I'm about 80% successful at cleaning them, meaning issue goes away. On Toyotas, Subarus, and Nissans, I'm about 40% successful at cleaning them.

Here's what I do: No guarantees...

I remove IAC. I suggest you purchase a new rubber gasket if your uses a rubber gasket.

I get a plastic butter dish. I place the IAC with the electronics on top in the dish. You don't want the cleaner to get into the electronics.

I get carburetor cleaner and some metal picks.

With the IAC in the dish, electronics to the top, tilt slightly back, fill the area around the valve with carburetor cleaner. Let sit for 15 minutes.

Dump out cleaner and use pick to gentle remove the carbon build up. Don't be rough.

After cleaning, spray out to remove rinse out carbon flakes.

Soak again.

Dump out and pick areas you missed before.

Do these two steps until you think nothing remains on the mechanism that would prevent normal operation.

Use shop air to dry out

Reinstall with new gasket, if need be, utilizing appropriate torque specs. On Fords, I normally can use existing gasket.

I then use bi-directional functionality on my scan tool to test the IAC while car is running. This functionality will probably not exist for you. So, run the car at idle, it should idle now. Then turn on A/C and headlights to cause the idle to go up. Then rev the car to 1500 and settle for a few moments, let it drop to idle. Do this same thing from 1500, 2000, 2500. You're trying to get your IAC to move throughout its range to ensure it can and does.

If any of these tests are bumpy or fails at this point, I suggest just replacing IAC.

That's what I do in a nutshell.

If you know for sure the IAC is stuck, replacing it will actually just save you time since you know the new one will work. Up to you.

Best of luck.

Coolant level is good

So, when I unplug the connector the idle is normal. But when I plug it back in the surge returns, wouldn't this mean that the problem is not a stuck IAC valve, but perhaps whatever module controls it?

what if you connect it back while running?

It will remain normal, until the next start-up cycle.

You need to know if it remains active when you reconnect. i mean during start it opens more for the rpm to rise a little and then just cannot return back to its idling position?

Yes it remains active when I re-connect. And it does seem like it cannot return to its idling position after a startup.

Then GeekDIYMechanic posted some good info.

Yes he did. In the top to hole there is excessive amounts of air suction, when I partially plug it with my finger it wants to sucks my finger in but the idle goes back to normal. (While I have it partially plugged)