First thing, its not mechanical in any way. The butterflies are completely closed all cables are not taunt at all. What is causing this is my idle air control value being told to stay open. I know this as i have put my finger over the IAC hole in the TB and there was a bit of suction, and it dropped my idle down to where it should be. I have pulled the valves off, checked the solonoids, swapped them with known good ones. No solution. So i know the valves are working and not getting stuck open.

Can someone please enlighten me as to what could be telling these valves to stay open. When i put my powerFC in, the problem gets worse. If i start my car cold with the stock ECU in, it will idle at about 1200 till it warms up. Then it goes to about 1500. With the PFC it idles it about 2250.

I've swapped out the air intake temp sensor. My next guess is my water temp sensor. But i am just taking stabs in the dark. Anyone who has any ideas please share as i am at the end of my witts.

 

Un plug the Idle speed control ,the white plug and see what it does .Mine has a Power FC that will not learn to idle with out the AC on. So I just unpluged it and the car starts hot or cold, no hot wax rod either . Also check for air leaks or vacuum leaks .

 

If you remove isc you can look for carbon and oil build up. you can clean it with carb cleaner. It may be held open some.

 

Busted, please read my post. I've pulled them, tested them. They are in perfect working order. If you just read the title and decide to throw out a suggestion don't bother replying. Its a waste of both our time.

Garco- The strange thing is that during the summer, if my car sat for an hour or 2 and heat soaked it would start and idle fine. As its gotten colder it no longer will. I've unplugged the IAC when it was running in the summer and the idle would drop down to where it should be, but when i got home and let it sit I could not get it to start without plugging it back in. In the winter if i unplug the IAC behind the UIM it will still idle high, but lower than with it plugged in. I've checked for vacuum leaks, and not found any. I also don't think its a vacuum issue as i have taken of the intake elbow and put my finger over the IAC hole and the idle dropped to 800.

 

This has been covered a bunch on the PFC forum.

Here's the deal, PFC idle control is iffy at best. When you have setup everything right and it still doesn't control idle well you have little choice to just go full manual idle control. When you go full manual idle you need to setup the PFC with a datalogit to get the idle perfect, it can be done without doing this but it's more stable and consistent this way. Thesel PFC adjustments cannot be done with the commander. When finished, you will still need to adjust the idle bleed screw between winter and summer months as the air density affects idle rpm. You can keep the wax rod if you want it to idle high when cold but I prefer to eliminate it and the cooling lines to the TB as well as removing the ISC and installing a blocking plate. Your motor and ignition need to be in good condition to prevent the A/C from bogging the motor down when you go manual idle control, otherwise you have to set the static idle very high. With a fresh motor and strong ignition there is only a 150-200 rpm difference in idle with A/C on.

Bring it to Texas one day and I can set it up for you at a reasonable rate. I love manual idle control.

 

You said air density affects idle rpm, so that means you have to back out or turn in the air bleed screw?

I have my screw a half turn shy of it being fully closed.

And my idle wont go down below 1300, but mostly it stays at 1400-1500. Mind you its a bit cooler out now, about 45-50F.

And sometimes, just sometimes the car bogs coming out of a complete stop.

 

There are other sources of idle air: the two screw adjusters on the front of the TB, the hose that connects to the LIM to the turbo outlet, the wax rod, and the ISC. If the bleed screw cannot lower idle enough for your needs then try the screw adjuster on the front of the TB, the one that affects the lower/primary intake runners.

 

Ah ok i see now.

What would be the future risk of having the air bleed screw fully closed? Some people say its for use when you wanna fine tune to have the perfect idle? And some people say factory says it never needs adjustment and you should leave it alone, how did they set it at factory? Fully closed?

And do i have to reset the ecu after making these adjustments??

TIA

 

Anyone?