Weird Idle problem (UPDATED) Still need help!
 

When I slow down to a stop and press in the clutch or put it in neutral, the car idle drops down real low (to about 600 rpm) for about two seconds and then jumps back up and idles at normal (about 900 rpm)

Anybody have any idea what could be causing it? It sounds like it's going to die on me sometimes.


UPDATE:

Ok cleaned out the throttle body and the IAC/IAC passage. It has completely reversed the issue now. Instead of going low a few hundred RPMs before leveling out, it goes a few hundred high before it levels out.

Could I have done something wrong when hooking up the throttle position sensor or the IAC?

Also, should it have been this nasty in the throttle body and intake?

Attachment 20639

Attachment 20640

Attachment 20641

Could be a problem with the IAC motor or the IAC passage in the throttle body.

thanks I'll check it out and get back

updated with new issues

anybody?

Appears where before it was idling low, and stalling, after you cleaned the TB its idling too high, although the IAC seems to be able to get it under control. You may have a leaky gasket, a torn inlet elbow, etc. Maybe the blades aren't closing all the way.

\When you cleaned the IAC motor pintle, did you attempt to move it at all? You aren't supposed to attempt to move the pintle, except to adjust the correct length when the IAC motor is brand new. Did you also avoid getting whatever you cleaned the TB with in the windings of the IAC pintle?

When you get that much soot in the intake, its usually from oil being carried into the top of the TB by the vent line to the passenger side valve cover. If you have excessive blowby, its going to pressure the crankcase, and cause the air flow in that line to reverse, and blow oil droplets into the TB. When you took the top cover off the TB, was there a puddle of oil in the top chamber?

The worst part about it is that it is taking a long time for the RPMs to go done in between shifts. When ever I go up a gear while accelerating, it feels like the transmission is spinning or something in the shifter knob. If feels really awkward but goes away after I release the clutch and the gear engages.

I made sure not to touch the pintle at all. I did spray it with MAF cleaner though, could that have hurt it any? I tried to spray it only on the very end, but did accidentally spray on the spring-like part (is that the winding you were talking about?)

There wasnt any oil in there I don't believe, just a bunch of dried up carbon. It's been about 3000 miles since it was rebuilt. Are you thinking maybe the rings didn't seat correctly or could there be something else causing it?

Your saying that about the torn inlet elbow reminded about something. I cleaned the MAF, and trying to fit it back into the elbow was a PITA. I'm still not sure we were able to get it to fit in there tight. Could that be the problem?

Thanks again for all the information you bring

Ok it got worse today. The only time it goes down to normal idle is after the car as been completely stopped for a couple seconds

Whenever the car is moving, if the clutch is depressed or if it is in neutral it revs at about 2k rpm. It will rev up to that even if it is at a lower rpm when I take it out of gear

Do you have to reset the IAC?

i think the ecu idles up when the car is in motion to compensate for upshifts (but 2000 is way too high)that maybe why the car only does it when in motion. i had a very similar situation upon installing a new 52 mm tb ,after the install the car would idle very high when in motion but when stopped it would be normal, if your car does this it probably isnt the iac my throttle blades werent closing all the way and required some minor porting with a fine grit sand paper .like injineer says check to make sure your blades are closing use new gaskets every time and make sure they match your old ones

Car wasn't really doing it on the way home from work

Took the elbow off, and it seemed like the blades were closing just fine? Is there any better way to check for sure?

Also, does there need to be a good seal where the vacuum hose connects to the elbow?

It should be a fairly snug fit for the vacuum lines at the throttle body. It sounds like you have a lazy idle air control valve. The fact that it's now reversed since you've removed it and reinstalled it makes it seem like it's sticking in one position and eventually moving. I would replace the control valve. They are a bit pricey at about a $110 but it sounds a lot like it. If you have access to a scanner you could control the iac motor and see if idle speed responds correctly with iac position.

Could this be the problem?

Attachment 19670

Or this?

Attachment 19671

Yes and yes. Those are both vacuum leaks.

well fixed both of those I think...

and now it's even worse. Don't know where else to look.