4.4i high idle after TB gasket replacement

[ChevDog1]

Last week, I finally got around to replacing the leaking TB gasket on my 4.4. This has cured the stumble at very cold starts (freezing and below), but seems to have created a new problem. I drove the car around all day yesterday doing xmas shopping with my wife, and it now idles a bit high when it's warmed up. I'm guessing that I must have created a small vacuum leak somewhere when I was replacing the gasket. Any ideas on where/what to look for? I did find a bad vacuum hose (the 1/8" one at the intake elbow), which I replaced while I was in there.

The car used to run perfectly when warm, and had a bad stumble/misfire/SES light if you let it sit outside overnight in freezing temps. Now the cold starts are cured, but it has a high idle when warm. My best guess is that the new TB gasket cure the cold start issue, but I created another leak in the process which is causing the high idle when warm.

[LeiZ]

From what I read before, the high idle at warm might be due to, I'm not even 80% sure, secondary air system. I just very vaguely remember that on top of my head.

Good Luck!

[Helihover]

I would double check the boots in between your TB and the mass air flow sensor. Those can crack, create a vacum leak, and not be that visible. You may have opened up a crack while replacing the TB gasket.

[ChevDog1]

Thanks, I will check those boots while I'm rooting around in there tonight.

[ChevDog1]

I went back through and checked everything I touched while replacing the TB gasket. Can't find anything that would be causing the high idle. It's currently idling about 800rpm warm and in neutral. Drops slightly in gear. Its just a couple hundred rpm over what it used to be.

When this started, I had also cleaned the TB. Any chance I did something to cause this while cleaning?

[upallnight]

Could be that the computer adapted to your leaky TB Gasket and remap itself. Either disconnect the battery and hope the computer reset itself and learn the new conditions or just drive around and hope the computer relearn the new conditions.

If you have BMW scanning software perhaps you can get the computer to relearn.

[ChevDog1]

I'll put about 500 miles on it over Thanksgiving, so I guess I'll just leave it alone for a while and see what happens. If I feel ambitious tonight, maybe I'll disconnect the battery and see if that helps. I can't seem to find anything else wrong, so this is as likely as anything.