Back Ground: car was always a southern CA Car. Alway's idles Fine. I'm now in Detroit MI (cold), and Made my way here Through Memphis (couple a months)(cold in the winter).

The car seems to start normal then Idle normal in the cold. It will Genreally Idle to about maybe 2000 RPM. Then once warmed and you can see the water temp going to Normal range. Idle will drop and do the Fluxuating (surging) Idle from normal all the way back to about 2K Rpm. spending about 2 seconds in each RPM (normal and 2K).

It Happened in Memphis in the winter in 2004. Took it to the shop, they had a problem with it, suggested I just drive it like that. They called me back and said that they fixed it "idle control unit was dirty". Prior to me having the problem I had a Water leak. Tried to fix it with a Liquid seal (stupid move, told never to do that again). Car Runs fine for two years.

winter 2006 detroit MI, It starts happening again. Take it to two shops. Told both about the above Memphis story ("dirty idle control unit"". Both couldn't FIX. I Didn't drive it for a while. Summer came around, and it runs like a champ. 30 MPG's beautiful. normal Idle.

Car has 230K miles. Runs like a champ during the summer and gets 30MPG, can't get rid of it. Gonna drive it until the tires fall off.

I have a hunch if I change it to a cold weather thermostat that it might fix the problem if it's running warmer??? No Idea, not even the shop's know.

Any suggestions?? Sorry so Long.... This time I'm going to do the work myself....

Thanks...

 

I searched on idle pulsing. I found the exact fix to my surging idle when cold. The fix was the plastic washer/bushing on the cold air idle valve that had backed out. I screwed it in and the problem was solved.

 

Yea you know I saw a number of idle problems posted and the majority that I though was the surging/pulsing idle when cold. My car idles normal when the car is cold but when it warms in cold temerature (outside temps) it has the surging idle.

Didn't come up with anything in pulsing idle.

Thanks

 

Did they clean & test the Air Boost, Electronic Air Control (AKA IAC) & the Fast Idle Thermal (FIT) valves? If the FIT valve is dirty or out of adjustment it can cause the engine to receive too much air after the car has warmed up. Acting like a vacuum leak.

Another thing to try would be to bleed the coolant system and get rid of any air pockets that might be in the system.

Warm idle problems are usually associated with:
1. The idle air control valve IAC
2. The other idle control valves, FIT & Air Boost.
3. Engine coolant temperature sensor (ECT) Faulty sensor or as simple as a trapped air bubble.
If your Idle is extremely low these two come into play (not surging)
4. Fuel Injectors
5. Electrical load detector error (ELD) would trip a DTC/CEL