just an update
my mechanic fixed the idle and restored it how it is supposed to be
the car starts up differently, shuts off differently, and drives a lot smoother.
when the air conditioner turns on there isn't a sudden jolt in the car as there was before.
we also had the engine in the 5-6K range and allowed it to drop in N, and i did observe what you were saying about falling past 750RPM.
i never noticed anything before so i cannot make an accurate comparison but what happens now from 3rd gear and 5-6K RPM, when we throw it in N, the RPM needle hits 1K and then bounces and slowly bounces until it adjusts itself to an idle RPM.
thanks for all your help.

only one problem though i think we have a vacuum leak somewhere because SOMETIMES when the car is idling, it jumps from 1K to 1.5K RPM but then remains calm.
there is not specific situation that causes this happen, it only happens sometimes and only at a stop.

 

I'm glad it's better. But like I said, dropping from high RPMs is a difficult thing for the control system. Your description of it bouncing at 1000 on it's way down to idle might be normal.

Vacuum leaks can be a real pain to find & fix. Sometimes you can spray (short bursts) from an un-lit propane torch around a suspected leak. If it sucks in it'll add to the fuel & the idle speed will respond. Spray short bursts so you don't build up an explosive atmosphere around your engine...

 

Well my mechanic sprayed some shit around the IM and TB area and there is no leaks.
So what he is telling me is that it could be a bad idle control. Not sure what that part is called.
The idle bounces from 1K to 1.5K while it is idling only happens sometimes. When I turned on the car this morning the car idled at 1.5-1.7K and when I let go of the clutch in 1st Gear it didn't even stall, it just drove itself. By the time I got the school (say 10 blocks of driving) the idle was below 1K RPM. It varies in its fluctuations, which is the reason he thinks its a bad idle control.

Any suggestions for us to look further?

Also, does ANYONE believe the "reset your ecu" trick? For the longest time I used to believe this but now I don't. The trick is when you remove your battery for an extended period of time (10 minutes) and reconnect it, your ECU will "relearn" the new air/fuel settings. Such as intake, exhaust, header, etc. I always thought this was true but recently started doubting the validity of this myth.

 

I got it from the Helm manuals for 2 former cars. '95 Integra & '98 Accord. It's the last part of the 'set base idle' procedure. It seemed to work for the Integra, but the Accord never really displayed a messed-up idle.

The 'bad idle control' sounds like he means the IACV (Idle Air Control Valve). That's #9 on the back of the intake manifold.

 

okay, i need your help again. this time the idle is surging non-stop. when im in N idling the idle surges like im revving the envine over and over again up to a little below 2K. we replaced a IACV, replaced the gasket between the throttle body and intake manifold.

the problem has only been resolved because we close the idle valve all the way shut. if we open it even a little the idle will surge again. currently the engine idles at 850-950, normal idle values. but it's awkward because when we turn the air conditioner on, the idle does not jump like its supposed to.

either way: idle valve is completely closed with no surge. engine idles normal now. if idle valve opens a bit, surge goes crazy. air conditioner does not affect idle like it normally would.

should i worry? what's the real problem causing the idle surge.

no CELs.

 

OK I read back over the whole thread. I mentioned the procedure for setting the "BASE" idle, but never explained it. Did you find this somewhere? Just so I don't take anything for granted, here's the cliff notes...

First things first:
Find & fix all vacuum leaks. Get rid of any air from the cooling system.
Throttle cable MUST have a little slack.
Mechanical stop for the throttle should just barely prevent throttle from wedging stuck closed; this should not be used to adjust idle.

Warm up the engine completely. ALL electrical loads switched off.
Unplug the wire from the IACV (#9 in the picture).
It'll almost stall; adjust idle screw #1 for 500 rpm.
Turn it off & let it cool down & plug the IACV back in.
Reset ECU (pull fuse #13 at right-side end of dashboard).
Start the engine & let it warm up without touching the gas pedal at all.

If that's no good, maybe your throttle-position sensor is bad? It's not numbered, but it's located on the throttle shaft opposite the cable pulleys. Look for proper voltages, I'm not sure of them. Something like 0.45v when it's closed & 5.0v when it's open & smooth variation in between?

If you have to close the idle valve (#1) all the way, then maybe there's a vacuum leak?

ps... When you turn on the AC, it shouldn't surge. It's supposed to add enough air to maintain about constant RPM. If the system did NOTHING, then AC would cause the RPM to drop or stall.

 

there are two hoses behind the IM that were leaking. that was the source of all problems, we never saw it because it was tucked away deep in the back, but once my mechanic started digging around he found it.
wow...headache and a half. thanks a lot again.