On cold startup,when outside temps are in 20s,or colder, starts and settles out at about 900rpm.Instead of warming,and continuing to idle down normally to 625-650,it stays at 900.If I turn off engine,and restart after a short period it will go ahead and idle down,on second restart.Engine temp gage still on cool side.Ive replaced idle control sensor on throttlebody,and coolant sensor on lower drivers side of engine.It seems to work fine on temps above 32 degrees. IF SOMEONE CAN HELP ME ON THIS PROBLEM,IT WOULD BE APPRECIATED!

 

thermostat maybe .. its what mine was doing , rubber o ring around the themostat was letting coolant bypass thus free flowing the coolant thus not letting the engine come up to full temp and making it idle higher

 

I agree with above....change-out the thermostat. Had one that stuck open and engine would never come-up to normal operating temp which caused high idle and reduced fuel mileage.

 

Thanks,Double d for your input!

 

Thanks LannyL81 for your input!

 

did that work for ya robD?

 

My blazer is doing something very similar but according to the temp guage it is running at normal temp and even sometimes goes a little higher than I am used to seeing. Could this still be the thermostat or is it maybe the temp sensor and then that is giving false reading to PCM?

 

Double d,Dont know yet? Weather been nasty,but put in new 180 about a year ago.Like I said it wont idle down at temps in the lower 20s or colder,but temp guage works fine to full operating temp and it still doesnt idle down,in these temps.I kill the engine and restart, it idles down perfectly.It takes 2 starts for some reason?

 

Lazurus,Dont know for sure,but since its running a little hotter, I would go with new thermostat.Chances are its sticking.