High Idle on Startup?

[dukbludvl]

Hey all, my 2000 Yukon with 71K miles (5.3L) recently started to idle a bit high at startup. It only seems to do it on startup -- it usually idles at 800-1000 rpm instead of 500-550 like it used to. As soon as I put the truck into gear, it drops back down to the normal 500-550 and doesn't really idle high again.

 

I think I've only noticed it on cold startups. Is this normal or abnormal? If it's not right, what could be causing this?

 

I recently moved within a mile of work, so for the past 2 weeks I've been making a lot more short trips where the engine does not warm to full operating temperature. Could this be causing the high idle?

 

Are there other things I should check out?

 

Thanks!

[budhayes3]

That's normal for a cold start, the PCM will command the IAC to hold the idle a little higher until the engine starts to heat up.

[Machine]

That sounds normal. Our 5.3's do the exact same thing at start-up

[99silveradoz71]

That sounds normal. Our 5.3's do the exact same thing at start-up

 

 

 

 

 

Yep, I know mine gets a bit louder during the cold months. Give her some extra time to warm up and she's good to go. The other thing is the cold weather shift pattern where the truck won't shift until the tranny is warm.