I changed my coolant a year ago according to instructions on motorvate.ca
http://www.motorvate.ca/mvp.php/502

According to them we must open the valve in the heater core, to allow the coolant to drain out of it by pressing buttons on auto climate control untill Code 43 is displayed.

I did all that but I think my car got some rough idle since then.
May be we are supposed to close the valve in heater core after coolant change ?

 

you changed your coolant a year ago but are noticing it now?

 

It wasn't that bad , also I used Lucas gas treatment at that time so I thought that's the reason.
Few weeks after changing the coolant my alternator and belts were replaced and since then I got more vibration in idle.

But still I wanna know if anyone chaged coolant like in motorvate.ca writeup.

 

i did it that way w/ auto CC, no problems. ran water through it several times until it came out clean, refilled w/ prestone and it's been good since. i may be wrong, but i don't think that flushing your coolant can really cause vibration at idle though.