cold start-up oddity?

[john112deere]

It was well below zero last night, probably around zero now.

Went down to start up my truck and let it warm up for a few minutes.

Fired up pretty good, I made sure all the gauges read what they were supposed to, then turned on the defroster fan and walked to my roommates car to start it up for him.

Just about when I got to his car (5-8 seconds, maybe?) the idle kicked up on the Ranger. Rough guess...maybe from normal (7-800?) to a somewhere around 11-1200. Truck doesn't have a tach, though, so I could be WAY off the mark with those numbers.

I know on newer cars, they'll often go right to a high idle immediately on a cold start-up, but I don't think this truck used to do that. Can't remember for sure, though. So...normal behavior for a '97 OBDII Ranger? Sluggish IAC that takes too long to kick up the idle? Some sort of weird vacuum leak that's making the idle go high when it shouldn't?

Or is this just one of those "vehicles do weird things when it's cold" times, and I should just be happy the darn thing started?

Thanks!

 

[expeditionman]

hard to say, i know my truck (97 expedition)does that when its real cold out, but my wifes 01 windstar goes to high idle right on start up

 

[Bob Ayers]

Ian, how long did it take to return to "normal" idle?

 

[john112deere]

I'd guess maybe 60-90 seconds, but the speed dropped down more slowly. It's hard to say, though, because without a tachometer I'm going based only on sound, and as fluids (e.g. power steering) warm up, the noises change somewhat anyway.

When it "kicked" up to the high idle, it was an almost instantaneous increase in speed.