My vac ball was leaking, so I removed it. Now I have noticed the gas pedal on cold start ups will not sink in a little so the car can move to fast Idle. So now I have a few questions..

1. what controls the fast Idle?
2. What device is pulling my gas pedal down, is it another function of the cruise control?
3. What roles does the Vac ball play in the vacuum system?
4. Do I need to replace the vac ball or is it another problem?

The car is a 1990 GTA 350 TPI MAP

 

To the best of my knowledge:

1. The iac controls every bit of the idle, nothing else.
2. The cruise control is the only thing that should move the gas pedal and only when youre using it, are you sure your linkage isnt jamming up or something sticking your throttle plates?
3. The vacuum ball holds a vacuum so under conditions when your engine isnt producing sufficient vacuum, things that rely on it have a reserve.
4. You should replace it, yes, but I would imagine its not related to your problem and you should be looking elsewhere. Cleaning your iac, linkage and throttle blades is something you should do to get started. You can find articles on these with little effort.

 

Thanks for the reply, and I will replace it. But back to the idle at start up...the car always did that with out fail, it looked like normal operation to me. I'd turn the key, she would spark up, gas pedal would sink in, rpms rise to 1300 and as she worms up rpms fall back down. Everything is clean, there is now a 406 under the TPI. I was having surging porblems so I went through my vacuum lines and found the cracked vac ball, so took it out. Now every time I fire the car up, pedal does not sink in, and I have to put my foot in it to get it to 1300 (fast idle).

So the pedal sinking in at cold start up is not normal?
It gave me no issues at all

 

To provide vacuum when manifold vacuum is low.

 

What all devices is it providing vacuum for?

 

As was said the pedal shouldn't move on its own. Check all that is physically connected.
Please post the solution.

 

Ya, look at it this way, the pedal controls the throttle linkage and nothing more. On an fi car, the idle is purely controlled by the idle air control valve, which is run purely off of the ecm sending volts to it, it has nothing at all to do with the throttle linkage and is not at all connected to it. It will correct to an extent any extra air that is coming in from other sources like a vacuum leak.

I honostly have no clue why your pedal would do that when you start it, makes 0 sense. The pedal sinking at high idle just is not something that should or reasonably could happen. Im not saying it does or doesnt do it but it just doesnt make any sense to me outside of maybe a really weak throttle return spring and a really strong idle vacuum causing vacuum to pull your throttle blades a little bit. But if that was the case, youd have throttle sticking open issues galore.

Check your linkages, clean your iac, check your tps, replace your ball and check for vacuum leaks.

Did you get a prom burned for the 406, put in higher flow injectors or do anything else with the new motor? A little more background would be helpful .

 

Yes I'm still working on the tune with tuner pro
It has 42lb ford racing injectors
Stock TPI
Fuel pressure set at 44psi
Min Air set at 700 rpm in diagnostic mode
Idle set in prom for 800rpm
Dart Iron eagle 200 heads
460/480 speed pro cam
1.7 ratio scorpion roller rockers
Tps set at .54V
Super Comp headers, mufflex 4" exhaust

Throttle return spring has lots of pressure
Thanks for all the replys so far

 

So all that should be happening is the IAC is to let in more air at cold start up to give you your fast idle?

 

Cruise control and all the HVAC pots under the dash.
If not in place and working , air vent position will change when vac drops as you accel

 

Thank you vetteoz