ok, I have finally gotten around to taking the intake off and the IAC valve. The IAC is definitely gunked up (the spring too and around the hole going into the valve). One question though, should the pintle be able to move when you have the valve off (and disconnected)??? It doesn't seem to easily. Can you take it out to clean easier???

thanks a bunch.

 

When I pulled mine out, I couldn't move my pintle by hand...they stay pretty stiff. The spring is very high tension too. Just soak the sucker up in carb cleaner and use a rag first..whatever you can't get with a rag, try with a fine wirebrush, toothpick wrapped in a shop towel...whatever gets in there.

 

I just figured out by accident that the pintle does come out by unscrewing it. How do you know how far to screw it back in?? And can you spray the cleaner in the hole as well??

 

Dont see the point of putting cleaner in the pintle hole..all it does is hold the thing. I assume you keep screwing it in until it stops...

 

Well, I am just curious if part of the problem is that the valve is sticking when going in and out? In which case it would still be a problem when I put it back in. I don't know if the intake cleaner spray would be harmless to the stuff inside the valve or not?

As for screwing it in, it doesn't appear to hit the "end". It has 2 little slots on the sides that fit in 2 grooves on the valve so you can screw it in that far but it all depends on where the thing inside is situated (how far in or out it is) as to how far the pintle sticks out once you hit those grooves (and can't turn it any more). I think the thing inside moved a bit during the process and that's why I'm thinking it may not get to the exact same position as before. Not sure if this will matter??? Do you see what I'm saying?

 

Well if you disconnect the battery and reset the computer...when you reconnect it and start the car, the car automatically moves the IAC valve open and then closed, to make sure it's got the right position down and that it's not half-way open or anything. This process is what normally makes a car stall out on the first start right after the ECM's been reset.

The carb cleaner...keep it away from the wiring and electronics/motor inside the valve...but the valve itself and spring, and the area around them, are generally plugged up with carbon, which is what makes the valve stick in the first place. Also..I forgot to mention this...you might want to keep the carb cleaner away from the O-Ring on the valve. I'm not sure if it'll eat it or not but it might.

 

ok, thanks for the tips nixon! I am keeping my fingers crossed that this and fixing the vaccum leak on one of the comlicated plastic hoses (that goes to the PCV and other things) will steady out the idle and eliminate the stalling. We'll see!

 

If the idle is hunting/surging...the IAC might help. If that doesn't work, might wanna check the TPS sensor. Sometimes the IAC might be too messed up to be fixable by cleaning it...but usually just cleaning it works.

 

Yeah, I'm definitely going to check the TPS too but if I remember correctly, do you not have to ensure that the idle is just right first??

 

I think you can check the TPS with the car in just the run position or something....don't have to start the car. The idle stop screw is what holds the car at its base idle...so you can check what the TPS reads with the car off because the throttle should still be cracked. Then slowly open the throttle and keep an eye out on the readings...they should rise up steadily until you hit WOT....but I cant remember any of the numbers so sorry, can't help ya there. Maybe someone else knows em.

 

Yeah, the IAC is a stepper motor. A stepper motor has multiple coils inside. Each pulse of a single coil moves the motor a prescribed distance- ex, one "step". So that pintle won't move easily. Don't put any cleaner "inside" the hole that the pintle comes out of, you can destroy the windings.

If the motor's sluggish, it should be replaced. The only cleaning that we can do is cleaning the tip of the pintle, and the passageway inside the throttle body (runs from the hole for the IAC down to the passenger side of the front of the throttle body blades.)

Now since you removed the pintle from the motor, you'll have to follow the correct procedure on resetting the IAC motor. This involves installing the pintle into the motor as far as possible! Otherwise, if you don't install the pintle back far enough, and you tighten the IAC motor into the throttle body, you can either strip out the threads on the throttle body (less likely) or damage the IAC motor (most likely). It'd get damaged because the pintle would be making contact with the IAC passageway, which would prevent you from screwing the IAC motor in all the way. If you force the IAC motor to screw in anyway, it'll damage the motor.

Remember too that it's a steel motor going into an aluminum throttle body, and any time you put a steel bolt into aluminum, you can run the risk of stripping the aluminum out. Torque spec is only 15 ft/lbs, which is basically "a little more then hand tight."

I hope that sheds some more light on things!

 

Learn something new every day! I didn't realize the IAC motor had various positions...I thought it was just an open/closed thing. Thanks for the additional info Tom!

 

No problem! Stepper motors can be found in robotics and computers; it allows for a varying speed (your CDROM spinning fast and then slow), positioning (each step moves the motor the same distance), and stopping ability. You just can't hook positive and negative up to a stepper motor and expect the motor to spin. It'll move one "step". For as long as you apply power, it'll "hold" the motor at that step (robotics, think of an arm lifting something up.) In the case of our cars, we get that "exact" positioning.

So if you wanted a 4-coil motor to spin one revolution, at it's most basic, you'd wire up 4 switches- one for each coil. Then you'd press each switch in order (1-2-3-4). 'Course that's where electronics take over... and we're not talking Radio Shack stuff. http://www.allelectronics.com if ya get bored! You can tell I'm slightly bored if I'm talking about all this...

 

THanks Tom, that does shed some more light on things! I will have to maybe measure the distance to the hole in the throttle body and the distance the pintle is sticking out to make sure I dont damage it.