Fluctuating Idle, 98 Honda Civic

[hatchRus]

Whats up TST,
I recently picked up a 98 civic for dirt cheap!
I threw a battery in, changed out the rotors and got her started, rolling good.
Once the car warms up I get that roaming idle issue, where its reving from high to low. I did some surfing on HT, and a few other sites and they recommend cleaning out the IACV. So I did that, and the roaming is worse!
Does anyone have any experience with this issue?
Any help would be appreciated. Im trying to get this car on the road soon.

Corey

[DPancoast]

You could try a new iacv

OR a more easy thing to try is bleeding your coolant system. Sounds like you have some air in there

[hatchRus]

I think im going to try the bleed the coolant system route before trying to buy a new iacv. From searching the forums that seem like the next logical step.
I hope this works!

[cvcrcr99]

No vacuum leaks I presume since the car doesn't start to act up until it is warm. No overheating issues?

98 Civic DX/LX/EX? Any mods done to it?

I have a spare IACV from my D16y8 that should work for you in my garage. I swapped in a H22, so I no longer need the D series parts anyways.

[hatchRus]

cvcrcr99, I did a visual check for vacuum leaks and didn't notice anything. The car is bone stock, 98 civic hatch dx. It has not overheat on me either. Im thinking its either I introduce some air into the system when taking off the iacv, or the iavc is on its last leg. Im going to try and bleed the system later today. If that doesnt work, ill be shooting you an IM about that spare iacv you have

[cvcrcr99]

Well, you wouldn't be able to see a vacuum leak unless there is a gaping hole after the throttle body, or by a smoke test. If it was a vacuum leak, the engine would surge as soon as you turn it on, not once warmed up. When you removed the IACV, you pulled it off of the IM, so air in that system is fine ;). The air that you may have introduced into the coolant system is almost negligible if any at all. Also, air in the system never caused an engine surge from what I have seen. It usually just causes an overheat to show up when sitting at idle.

It was either improperly bled when you got it, or the IACV needs to be replaced IMO. Let us know what you find out.

[hatchRus]

cvcrcr99,
After checking it out again today I think the IVAC is shot. I was looking through the haynes manual and they recommended to check the resistance between the plugs on the IVAC. anything between 16-28 ohms is good.. Well, im getting Zero ohms. And I think the reason is, while cleaning the IVAC I took off the 2 screws that connect the green rotary part to the valve. I dont think I was supposed to separate that part. So..... If you still happen to have that IVAC for a D16Y7 laying around let me know..