extremely high idle

[MaxswellSpy]

Hey all! Ok so I got the fiero to finally start and run but am now dealing with an extremely high idle.
when the car is cold it will seek between 1k and 3k rpm before warming and settling right around 3k.
I have pulled and cleaned the iac and ran the "stick the finger over the iac hole to see if it dies test" which it does. The car has the original egr so im going to change that out.. Anything else I should look at? All help is much appreciated.
 Iain

[Roger]

Remove the tube from the air box and throttle intake.
Use a flashlight to look into the intake to confirm that the butterfly is closing completely.
Although I have never heard of this part being a problem; make certain that the TPS (Throttle Position Sensor) is not damaged and that its contacts are not corroded.
The EGR can be an issue. Any vacuum leak can be an issue.

1. Do you have a multimeter? (I can get into this later)
2. Do you have a vacuum gauge?
3. If it's simple, you might want to have a can of throttle body cleaner to spray on the intake butterfly to remove any varnish or residue that may prevent it from closing.
4. If you remove the EGR, make sure the pintle is not stuck and moves freely. Also you would need to pull a vacuum on it to see if it will hold vacuum. You can at the very least, push the pintle inward, stick your finger over the vent opening (where the vacuum hose attaches) then release the pintle and you should feel some suction on your finger.
5. Do NOT remove the TPS until you have exhausted all other options.
6. Make sure the the throttle cable moves freely and does not stick and that it returns to the proper stop point.

Anybody else have any ideas?
Keep us abreast of how you are coming along with this.

[Fierofool]

The TPS will usually give you a flat spot when accelerating rather than a high idle.  I would suspect a cracked EGR tube or one of the vacuum lines underneath the throttle body has been left off or come loose. 

When you pulled, cleaned and reset the IAC valve, was it of the type with a round shaft or one with slots on the side?  The slotted one must be rocked side to side while putting pressure on the end but the round shaft IAC can be screwed in.  Did you set the pintel height at 1 1/8 inch before reinstalling?  While it was out, did you flush the IAC port with carb cleaner? 

Other areas of vacuum leaks can be at the MAP sensor.  The line underneath that attaches to the intake and the fuel pressure regulator is out of site and can be off without being seen. 

[f85gtron]

Reset the iac before you go much further, just to rule that out.
1) Insert paperclip into aldl,
2) turn ignition to on, but don't start.
3) iac should be making noise. Wait 30 seconds, then pull iac plug.
4) turn off ignition, remove paperclip
5) reset ecm by disconnecting battery ground or ecm power weatherpack for a couple minutes.
6) drive for a few minutes over 35mph so it will relearn 0 steps.

[Raydar]

As I understand it, after you do whatever you're doing, the car needs to be driven to set the IAC. I'm thinking it has to be at normal operating temperature, and has to be driven at over 30 MPH for a few minutes.

[MaxswellSpy]

Thanks for the feedback all. Found a pretty horrendous vac leak from the egr tube by spraying carb cleaner and listening for rpm change. Gonna rob another tube from one of the parts cars and reset the iac tom after work.
Hopefully that completely sorts out the idle issues.

[f85gtron]

Glad you've found the source!  Please finish off the topic with any repairs made and their outcome, good or bad, so that others searching with similar issues can learn from your experience. It's getting harder to keep these 30 year old cars on the road! Keep us posted!
Ron

[Raydar]

Thanks for the feedback all. Found a pretty horrendous vac leak from the egr tube by spraying carb cleaner and listening for rpm change. Gonna rob another tube from one of the parts cars and reset the iac tom after work.
Hopefully that completely sorts out the idle issues.

Once you fix that leak, there is the largest possibility that the car won't idle at all (from my own experience.)
The 30+ MPH test drive should fix that, too.