http://www.92lude.com/idle_air...d.htm

Ok, last week my idle started to stumble like everyone elses, so I figured it was my IAC valve. Today, I was all ready to pull it apart and bypass it, but I figured I'd warm it up and try the finger test just to be sure. I got it to start stumbling, so I rev'd it up and put my finger over the hole. I could feel it pulling air in just like in the guide. When it came back down, it still stumbled. Not as bad as without, but still 400/500 RPM. And I can control when it stumbles too. If I'm in traffic, and I'm constantly reving up and letting the clutch in and out, it'll stumble, but if I'm pulling up to a light, and I let it stay in gear for a moment without pressing the gas before I let the clutch out and stop, it'll idle fine

 

The problem you are describing is not the surging idle they are talking about in that post. They are talking about an engine that fluctuates between ~750 to ~1500 RPM after warmup with NO stumbling. When was the last time you changed ignition parts or fuel filter? Check FPR and Fuel Pressure if you can.

 

Fuel filter was a few weeks ago. I'll check the plugs again but they should be fine. How do I check fuel pressure? And like I said, it doesn't happen all the time. Only if I'm in traffic or trying to back into a parking space or something. Something that involves letting the clutch in and out. If I'm moving and start to decel before I push the clutch in, it'll idle normally

 

Not just your plugs but cap, rotor and wires too. Pull the vacuum line off the fuel pressure regulator while it's idling and see if the idle increases. Another question; When you unplug the IACV while it's running, does the idle decrease?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by amckee &raquo;</TD></TR><TR><TD CLASS="quote"> Pull the vacuum line off the fuel pressure regulator while it's idling and see if the idle increases. </TD></TR></TABLE>

If you do that, you now have a vacuum leak, so of course the idle will increase.

 

make sure you dont have a monster sized VAC leak that is causing you to throw the code.

Example: You throw the IACV code, you clean the IACV and still throw the code. FITV is fine. If you hear a hissing or the exhuast tone of the motor has changed significantly you got a leak.

Try spraying some carb cleaner around the intake manifold while the car is idling. If you see a massive mount of bubbles and hear the hissing, it be leaking

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hawkze_2.3 &raquo;</TD></TR><TR><TD CLASS="quote">If you do that, you now have a vacuum leak, so of course the idle will increase. </TD></TR></TABLE>Go pull a vacuum line from another small line location such as the boost valve or the cruise control and the idle will momentarily rise and then fall if the IACV is working and there aren't any other gross leaks. But if it makes you feel better I'll suggest he plug the line with his thumb. Idle should still increase.

 

Well, it seems to only happen on very cold days (below 32). And it never thew a code

 

It sounds like your car is doing the same thing mine did, i replaced IAC and the other part to the right of IAC on the plenum connected to IAC through coolant lines, i had them laying around but my car runs good now

 

It wouldn't hurt to pull the IACV and clean it out with choke cleaner. Pull the top off the Fast idle valve . There is a little thimble surrounded by a donut. It sometimes gets loose. Just screw it back down if it is. If this doesn't fix it, could you describe your problem again. I'm not clear as to whether it's revving up and down or simply stumbling from a normal idle. Does it ever die when it stumbles? Has anyone messed with the idle screw. Too much idle bleed will cause idle surge.

 

Never messed with the idle screw. Sometimes, after it warms up, and I'm in traffic or a parking lot and I accelerate, then push the clutch in to idle, it'll fall to 200ish and sometimes die. When it falls, it'll try to pick itself back up, and sometimes it will

 

Did you ever figure out the problem? Cause my car is having the same Problem? So when you figure it out post it.
Thanks