My car idles very eratic during the cold weather. It never happens during the summer. When I first start the car everything is normal. After I drive a bit the idle gets screwed up and fluctuates between 1000 - 1500 at every stop. Sometimes if I turn the heater off or quickly fether the clutch it will stop (could be a coincidence). Sometimes it happens regardless of turning the heater on or off at all. It's been doing it for couple years and I can't figure it out. If it makes a dif. all of the EVAP and EGR crap has been removed from the car.

 

Is IAC valve functioning properly? Is it clear/clean? Is coolant level where it should be? Do you have a check engine light?

What does "all of the EVAP and EGR crap has been removed from the car. " mean?

... And you have two cars listed in your signature. Which one is doing this?

 

Sorry about that, it's my 96'. Not sure about the IAC valve. I haven't checked it out. Coolant is all good. The coolant system never over flows and the cooling fans rarely turn on but I think it's because of the Fluidyne radiator.

I do have check engine lights but they are because of the EVAP and the EGR systmes. What I mean by removed is, both of the systems have been completely removed from the car. It was the start of an engine bay clean up that never got finished. My goal is to have nothing in the engine bay but motor...... and eventually turbo. It's a ways off. Anyways, could the IAC valve be the issue. I haven't done any research on it.

 

It wouldnt hurt to do a full cleaning of the intake manual and the FITV and IACV on the back of it, and maybe the EGR ports, but hopefully you blocked those off with a custom plate when you remove the EGR system.

 

Yeah, I did put a cover plate where the EGR sat and I plugged any vac. ports that would have been left opened. So I've heard and am aware of the IACV, but what is the FITV? And what do you mean by "intake manual", are you talking about the intake manifold?

 

FITV = fast-idle thermal valve
Its underneath the throttle body, has coolant running thru it. Its job is to open up an air passage when cold, to provide a higher idle RPM until the engine warms up.

Possible problem is the guts of the FITV loosen up so it does not operate smoothly. Eventually the FITV will not close completely when warm; then your flaky idle will continue at even warmer engine temperatures.

FYI, your 2001 does not have an FITV. That function is built into the newer IACV & controlled by the ECU rather than directly by coolant temperature.

When you blocked off the mounting point for the EGR valve, did you do it in a way that blocks off the exhaust flow thru the EGR passageways? A properly-working EGR system will not flow during idle. Those passageways are internal in the manifold, maybe not blocked off??

 

It's been about three years since I took out the EGR system. My guess is that if the passage ways are internalto themanifold, I may not have done anything with them. Basically I fabricated a plate that would cover the entire opening with two mounting holes and used some high temp RTV gasket maker to seal it and then bolted the plate in place. I'm almost 100% sure there is no air getting through.

As far as the FITV goes, the idle is eratic at all stops even when the engine is at normal operating temp. Not just when the car is cold. Could it still be a possible issue?

 

That could still be a loose FITV. Like I said, it usually develops into a situation where the FITV doesnt close all the way even when the engine is warm.

 

check the FITV that was the same problem i had when i had the identical symptoms your car is having. Clean it up and put it back together, $0 fix, easy diy.

 

Yep, clean or at least take it off and tighten the plunger, you only need a standard slotted screwdriver.