My first SES ever on my '00 Silverado w/58,850 miles...I am so proud

Started noticing a few weeks ago that on cooler mornings on the initial startup I would get some erratic idling that would go away after about 30 seconds. Now that the weather has gotten much cooler and temps are in the 30's it has gotten worse.

This weekend I started the truck and it started fine, then about 20 seconds into running it got a little rough. I let it warm up a bit and then put it into reverse. The idle speed jumped about 200 rpms, then back down to normal and it REALLY began to run rough. At this point I am thinking if this continues it is going to set an SES...sure enough, about 5 seconds later the light comes on. Truck idles fine once warmed up and on any other start from there on during the day. It's only on the 1st start. The SES light went off by itself only to reset itself the following morning when the same things happened.

I am guessing something with the IAC, but I need to scan the truck to be sure. Anybody have any ideas what I can check really quickly to diagnose the problem? I figure I would just go to Pepboys and have them scan it. I have never done that before, do you just go up to the service desk and ask them to pull a code?

Thanks for any advice.

 

Any thoughts? Didn't happen this morning even though it was cool out.

 

make sure your Air tube is connected, no leaks, vaccum leaks, maf not installed all the way. My tube fell off my TB and it was surging and idling rough, so its a possibility.

Autozone scans for free.

 

While you're in there you can try cleaning the throttle body, if it's gummed up it will effect the IAC. Make sure your tune-up parts are up to date also (plugs, wires, etc.).

 

I'm interested in the solution, you have exactly described my 2000 Suburban.

The colder it is, the worse it runs and the longer it takes to smooth out. Will throw a multiple misfire if it's cold enough.

Keep me posted

 

i had this same problem. the rough idle. ended up being the plugs. replaced them and wires and the SES light went off.

i still have a hard time once in a while were it almost stalls out as soon as i turn it over. i am thinking fuel pump. i am going to replace the fuel filter 1st since it is cheaper and easier. plus it needs it anyway.

i cleaned my IAC valve too. worked better for a while. but it came back. might have to replace that eventually

 

Any smoke coming from the tailpipe, white smoke more specifically?

ANything done to this truck? Heads ever been off?

 

I think he fixed it.
Intake Manifold