Engine stalls when cold

[GTRS Fiero]

This was the IAC I pulled from my Fiero:


The tip was covered in carbon.  I used throttle-body cleaner to clean the IAC passage, then cleaned up with a paper towel that I had used to catch anything that didn't stay in the passage.  I'm not sure about the carbon, or how it got there, but surely the spring shouldn't be like that.

I can probably fix the spring, but I want to see if the IAC is bad or not.

[TopNotch]

Get a new one. That one is toast.

[Fierofool]

Retain the gasket.  Many new IACd's don't come with a new gasket. 

There are two style IAC's.  It relates to the pintle shaft.  One is smooth round and the other has 2 grooves running the length of it.  Adjustment procedure is different for each, but both should have an initial adjusted  length from the tip to the gasket flange of 1 1/8 inch.

To adjust the smooth shaft valve, hold the body in the palm of your cupped hand.  Using the fingers of that hand, pull the spring out of the notches in the pintle and screw the pintle toward the valve body until you have the correct length.  Be sure to locate the spring back into th notches on the back of the pintle head. 

To adjust the grooved shaft valve, hold the body in one hand and using your fingers of the other hand, press on the tip of the pintle and rock it side to side.  It will slowly move into the valve body until you have the desired length. 

If you go a little too far, don't worry.  It will adjust itself.  A problem and damage can occur is when you don't retract it far enough into the valve body. 

[Raydar]

To expand on what was already posted...
Once you reinstall the IAC, take the car for a drive. Let the engine get warmed up, and drive over 30-35 MPH.
I understand that is supposed to reset the IAC to spec.

[GTRS Fiero]

Get a new one. That one is toast.

More questions than answers.:
How/why did that happen?
Is this expected of an IAC that has about 2K miles on it, and was new 2 years ago?
Is that IAC unrepairable?

[GTRS Fiero]

Retain the gasket.  Many new IACd's don't come with a new gasket. 

There are two style IAC's.  It relates to the pintle shaft.  One is smooth round and the other has 2 grooves running the length of it.  Adjustment procedure is different for each, but both should have an initial adjusted  length from the tip to the gasket flange of 1 1/8 inch.

To adjust the smooth shaft valve, hold the body in the palm of your cupped hand.  Using the fingers of that hand, pull the spring out of the notches in the pintle and screw the pintle toward the valve body until you have the correct length.  Be sure to locate the spring back into th notches on the back of the pintle head. 

To adjust the grooved shaft valve, hold the body in one hand and using your fingers of the other hand, press on the tip of the pintle and rock it side to side.  It will slowly move into the valve body until you have the desired length. 

If you go a little too far, don't worry.  It will adjust itself.  A problem and damage can occur is when you don't retract it far enough into the valve body.

Um, gasket?  There was green stuff on the threads.  I did not do any of those things; i just put the new one in, and went for a drive.  I drove around the subdivision, but probably did not get over 35.

How much damage did I do?

[Fierofool]

Like Pat said.  That one is unusable.  You probably didn't hurt anything else.  The stuff on the threads is just a thread-locker, but there's supposed to be a gasket on that shoulder.  Check your old one if you still have it.

As for what appeared to be carbon on the pintle and in the port, the air for the IAC is from the engine.  Without going out and looking at a spare throttle body, I believe it comes from the lower intake manifold via the large hose at the lower back side of the throttle body. 

[GTRS Fiero]

The new chip from sinister is in.......and........IT'S PERFECT!  No more hunting, throttle is fast, smooth, and predictable. I only had a couple hiccups where the p.o. of the harness i bought had spliced the fuel pump circuit monitor wire to ignition. The 7730 didn't like that. So i wired it correctly to the fuel pump command wire and its happy now.  The other was that there was no original prom installed on the moates adapter to accommodate limp mode. I placed the sinister chip that came with the ecm in that spot and installed my new sinister chip in the main spot.
 No codes, runs smooth.  If you let out the clutch a little, it will nudge the throttle up to accommodate the load. You can do this pretty quickly, like in a backing situation, and it won't let the motor die.  I'm impressed.
I have to say that my favorite part is startup, just a small flare and then settles down.
Even highway running is smoother.   Very nice.
Ron

The little throttle nudge may be a function of the automatic transmission programming. 

So, now, are you ready to do your first for-somebody-else conversion?

I'm looking for more clarification on these posts.  Is the idle supposed to increase on an auto when shifted into gear?

[TopNotch]

The idle will drop when you put an automatic in gear, but not as much as it would if you didn't have a working idle air control. You can hear and feel the engine "fighting" the torque converter when you put the engine in gear, and if you let off the brake, the car will creep forward.