Weird Idle Surge Issue
 

So after I cleaned my throttle body and surrounding sensors I get a warm idel surge. The car starts and runs fine. Cold idle is fine.
After being driven when I put it in N or P the surge starts. It is a higher idle that drops briefly then back to a faster idle then drops again.
Since I have been dealing with the oil leak I haven't messed with it. Pulled the head off, took the intake manifold off. Cleaned everything inside and out. New gaskets for the head, intake, exhaust and surrounding areas.
Re-cleaned the sensors on the throttle body and reinstalled everything.
Surge is still there. It will go away when I disconnect the throttle angle sensor and plug it back in.

Took it for a 20 minute drive to make sure everything was working for the head removal and when I pulled back into the garage the surging wasn't happening. Thought maybe the drive had cleared it.

Here's the weird part.
When I turned off the head lights the surging started again. It would stop when I turned the lights back on (either parking or head lights)
Not sure if the lights draw enough power to cause the idle to increase above the range for the surge to happen.

'94 DX with a D15B7

Anyway, any thoughts on what to check would be much appreciated.

Thanks,
Brian

After further trouble shooting, when I cover the lower hole in the TB the surge stops. This leads me to believe it may be the FITV -( Fast Idle Thermo Valve) causing the issue. From my understanding there should be no vacuum in this hole when the engine is warm, but when I covered it, it nearly sucked the finger tip of my glove off.

Am I looking in the right direction?

have you done this?
http://www.team-integra.net/sections...articleid=1174

Yeah, it was cleaned with the rest of the TB. I monkeyed with the FITV more today to see if it helps. Will no tomorrow.
It is probably one of those two valves. Just need to figure out which one.

Yes that would be FITV stuck open. Some people (in warmer climates) just fabricate a little aluminum plate to block it off. It only is supposed to do anything when temperature is below 60 F.

What I am most confused by is the fact the surging stops when the lights are on. Doesn;t make any sense to me.

Could be bad grounds.

Turning the lights on causes the alternator to load down the engine just enough to make it stable. This is similar to putting the auto transmission in gear.

Basically too much air is bypassing the IACV, so with no load on the engine it goes too fast even after the ECU tries to slow it down by fully closing the IACV. It appears the problem is the FITV. You could also try closing the air screw so your bad FITV does the same thing as the air screw did.

I had the same problem. I replaced the FITV with a used one off eBay for $20. Problem solved.

mine does the opposite it surges when it is cold but once you run it its fine