When my car is cold it idles low and as it warms up the idles rise.

The fast idle air valve does the opposite of this, and i've been looking in the workshop manual and cant see how if this malfunctions how it would cause the opposite to happen of what its suppose to do.

The other thing that I think may be causing it is the idle speed control servo.

Has anyone had this happen before or know what could be causing it?

The Idle Speed Servo (Stepper Motor) can do this. It is quite common for it to fail normally due to one of its 2 coils going open circuit.

If you disconnect the cable from it you should see 6 terminals arranged in 2 groups of 3 like this:

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If with a multimeter you measure the resistance between the top and bottom terminals in each group of 3 you can test if it is OK.

1st generation are about 60 ohm and 2nd generations are about 80 ohm from top to bottom. The centre terminal in each group of 3 is an intermediate tap.

Rob

The fast idle air valve uses a wax pellet. When it is cool the valve is open, and when it gets hot it expands pushing a piston to stop airflow. The only way to check it is to take it off and heat it up to see if it closes at the correct temperature. I don't have the changeover temp at the moment but I'll have a look for it tomorrow morning.

All these sensors are after the MAF, that means it causes the car to run lean or rich, doesnt change the amount of fuel being injected, but then again the O2 would pick up these changes and make corrections so I guess it does.

Either way, the wax pellet would cause my car to idle lower when it heats up, not idle higher, even if it was opening at the wrong temp. Unless its complety buggered and stays open or closed all the time.

Anyways I tested the stepper motor according to rob_d and their is no continuity between any of the terminals, so time for a replace. Ill grab another fast idle air valve unit while im at it just to make sure.

If this doesnt fix the problem ill let you guys know.

I've only ever seen one half of one coil fail.

If you are not getting any continuity then I would suspect the way you are testing.

Rob

All these sensors are after the MAF, that means it causes the car to run lean or rich, doesnt change the amount of fuel being injected, but then again the O2 would pick up these changes and make corrections so I guess it does.

Either way, the wax pellet would cause my car to idle lower when it heats up, not idle higher, even if it was opening at the wrong temp. Unless its complety buggered and stays open or closed all the time.

Anyways I tested the stepper motor according to rob_d and their is no continuity between any of the terminals, so time for a replace. Ill grab another fast idle air valve unit while im at it just to make sure.

If this doesnt fix the problem ill let you guys know.
Good luck with that. Hope it fixes the problem :)

The one I got from the wreckers had no continuity at all, i tested every terminal and their was nothing, but I put it in the car and its working though. The car is running like new since ive changed this and the coolant temp sensor.

It was from a V6, I hope it doesnt make a difference that ive got a 4cyl?

Although I am worried about the no continuity, maybe its still buggered but not as much as my old one?

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You should be testing each group of 3 separately. ie the black or the red above.

On a 2nd Gen about 85 to 90 ohm between the top and bottom ie the 2 red below:

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and about 30 to 35 and 55 to 60 between the centre of the group of 3 and the top or bottom.

Similarly for the other side (group of 3)

Hope this helps.

Rob

The one I got from the wreckers had no continuity at all, i tested every terminal and their was nothing, but I put it in the car and its working though. The car is running like new since ive changed this and the coolant temp sensor.

It was from a V6, I hope it doesnt make a difference that ive got a 4cyl?

Although I am worried about the no continuity, maybe its still buggered but not as much as my old one?
Nah I'm 90% sure that the 2nd gens have the same throttle body setup

Yeah, it fits in fine and works but im just worried maybe the V6 has different settings to let more air in then the 4cyl one would. call me paranoid.

It seems to idle very very high when cold, but im not sure of the exact number because my tacho is stuffed but im going to fix that up soon. My idle speed adjusting screw is all the way in, so its impossible to lower my idle anymore, is that correct?

I know once its wamed up it should idle round 750, but cant seem to find anything about what it should idle at when cold?

What do peoples 2nd gens 4cyl idles sit at when engine is cold?